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Fulltext Diet-induced metabolic changes of the human gut microbiome: importance of short-chain fatty acids, methylamines and indoles

Abdul Rahim MBH, Chilloux J, Martinez-Gili L, Neves AL, Myridakis A, Gooderham N, et al.

Acta Diabetol, 2019 May;56(5):493-500.
PMID: 30903435 DOI: 10.1007/s00592-019-01312-x

The human gut is a home for more than 100 trillion bacteria, far more than all other microbial populations resident on the body's surface. The human gut microbiome is considered as a microbial organ symbiotically operating within the host. It is a collection of different cell lineages that are capable of communicating with each other and the host and has an ability to undergo self-replication for its repair and maintenance. As the gut microbiota is involved in many host processes including growth and development, an imbalance in its ecological composition may lead to disease and dysfunction in the human. Gut microbial degradation of nutrients produces bioactive metabolites that bind target receptors, activating signalling cascades, and modulating host metabolism. This review covers current findings on the nutritional and pharmacological roles of selective gut microbial metabolites, short-chain fatty acids, methylamines and indoles, as well as discussing nutritional interventions to modulate the microbiome.

Matched MeSH terms: Gastrointestinal Microbiome/drug effects; Gastrointestinal Microbiome/physiology*
Irritable bowel syndrome and inflammatory bowel disease overlap syndrome: pieces of the puzzle are falling into place

Abdul Rani R, Raja Ali RA, Lee YY

Intest Res, 2016 Oct;14(4):297-304.
PMID: 27799880

Irritable bowel syndrome (IBS), a common gastrointestinal disorder involving the gut-brain axis, and inflammatory bowel disease (IBD), a chronic relapsing inflammatory disorder, are both increasing in incidence and prevalence in Asia. Both have significant overlap in terms of symptoms, pathophysiology, and treatment, suggesting the possibility of IBS and IBD being a single disease entity albeit at opposite ends of the spectrum. We examined the similarities and differences in IBS and IBD, and offer new thoughts and approaches to the disease paradigm.

Matched MeSH terms: Gastrointestinal Microbiome
Fulltext Ecological and Ontogenetic Components of Larval Lake Sturgeon Gut Microbiota Assembly, Successional Dynamics, and Ecological Evaluation of Neutral Community Processes

Abdul Razak S, Scribner KT

Appl Environ Microbiol, 2020 05 05;86(10).
PMID: 32169941 DOI: 10.1128/AEM.02662-19

Gastrointestinal (GI) or gut microbiotas play essential roles in host development and physiology. These roles are influenced partly by the microbial community composition. During early developmental stages, the ecological processes underlying the assembly and successional changes in host GI community composition are influenced by numerous factors, including dispersal from the surrounding environment, age-dependent changes in the gut environment, and changes in dietary regimes. However, the relative importance of these factors to the gut microbiota is not well understood. We examined the effects of environmental (diet and water sources) and host early ontogenetic development on the diversity of and the compositional changes in the gut microbiota of a primitive teleost fish, the lake sturgeon (Acipenser fulvescens), based on massively parallel sequencing of the 16S rRNA gene. Fish larvae were raised in environments that differed in water source (stream versus filtered groundwater) and diet (supplemented versus nonsupplemented Artemia fish). We quantified the gut microbial community structure at three stages (prefeeding and 1 and 2 weeks after exogenous feeding began). The diversity declined and the community composition differed significantly among stages; however, only modest differences associated with dietary or water source treatments were documented. Many taxa present in the gut were over- or underrepresented relative to neutral expectations in each sampling period. The findings indicate dynamic relationships between the gut microbiota composition and host gastrointestinal physiology, with comparatively smaller influences being associated with the rearing environments. Neutral models of community assembly could not be rejected, but selectivity associated with microbe-host GI tract interactions through early ontogenetic stages was evident. The results have implications for sturgeon conservation and aquaculture production specifically and applications of microbe-based management in teleost fish generally.IMPORTANCE We quantified the effects of environment (diet and water sources) and host early ontogenetic development on the diversity of and compositional changes in gut microbial communities based on massively parallel sequencing of the 16S rRNA genes from the GI tracts of larval lake sturgeon (Acipenser fulvescens). The gut microbial community diversity declined and the community composition differed significantly among ontogenetic stages; however, only modest differences associated with dietary or water source treatments were documented. Selectivity associated with microbe-host GI tract interactions through early ontogenetic stages was evident. The results have implications for lake sturgeon and early larval ecology and survival in their natural habitat and for conservation and aquaculture production specifically, as well as applications of microbe-based management in teleost fish generally.

Matched MeSH terms: Gastrointestinal Microbiome*
Fulltext Urbanisation and its associated factors affecting human gut microbiota: where are we heading to?

Abjani F, Madhavan P, Chong PP, Chinna K, Rhodes CA, Lim YAL

Ann Hum Biol, 2023 Feb;50(1):137-147.
PMID: 36650931 DOI: 10.1080/03014460.2023.2170464

CONTEXT: The continuous rise in urbanisation and its associated factors has been reflected in the structure of the human gut ecosystem.
OBJECTIVE: The main focus of this review is to discuss and summarise the major risk factors associated with urbanisation that affect human gut microbiota thus affecting human health.
METHODS: Multiple medical literature databases, namely PubMed, Google, Google Scholar, and Web of Science were used to find relevant materials for urbanisation and its major factors affecting human gut microbiota/microbiome. Both layman and Medical Subject Headings (MeSH) terms were used in the search. Due to the scarcity of the data, no limitation was set on the publication date. Relevant materials in the English language which include case reports, chapters of books, journal articles, online news reports and medical records were included in this review.
RESULTS: Based on the data discussed in the review, it is quite clear that urbanisation and its associated factors have long-standing effects on the human gut microbiota that result in alterations of gut microbial diversity and composition. This is a matter of serious concern as chronic inflammatory diseases are on the rise in urbanised societies.
CONCLUSION: A better understanding of the factors associated with urbanisation will help us to identify and implement new biological and social approaches to prevent and treat diseases and improve health globally by deepening our understanding of these relationships and increasing studies across urbanisation gradients.HIGHLIGHTSHuman gut microbiota have been linked to almost every important function, including metabolism, intestinal homeostasis, immune system, biosynthesis of vitamins, brain processes, and behaviour.However, dysbiosis i.e., alteration in the composition and diversity of gut microbiota is associated with the pathogenesis of many chronic conditions.In the 21st century, urbanisation represents a major demographic shift in developed and developing countries.During this period of urbanisation, humans have been exposed to many environmental exposures, all of which have led to the dysbiosis of human gut microbiota.The main focus of the review is to discuss and summarise the major risk factors associated with urbanisation and how it affects the diversity and composition of gut microbiota which ultimately affects human health.

Matched MeSH terms: Gastrointestinal Microbiome*
Effect of Ipomoea aquatica ethanolic extract in streptozotocin (STZ) induced diabetic rats via1H NMR-based metabolomics approach

Abu Bakar Sajak A, Mediani A, Maulidiani, Mohd Dom NS, Machap C, Hamid M, et al.

Phytomedicine, 2017 Dec 01;36:201-209.
PMID: 29157816 DOI: 10.1016/j.phymed.2017.10.011

BACKGROUND: Ipomoea aquatica (locally known as "kangkung") has previously been reported to have hypoglycemic activities on glucose level in diabetes patients. However, the effect of I. aquatica ethanolic extract on the metabolites in the body has remained unknown.
PURPOSE: This study provides new insights on the changes of endogenous metabolites caused by I. aquatica ethanolic extract and improves the understanding on the therapeutic efficacy and mechanism of I. aquatica ethanolic extract.
METHODS: By using a combination of 1H nuclear magnetic resonance (NMR) with multivariate analysis (MVDA), the changes of metabolites due to I. aquatica ethanolic extract administration in obese diabetic-induced Sprague Dawley rats (OB+STZ+IA) were identified.
RESULTS: The results suggested 19 potential biomarkers with variable importance projections (VIP) above 0.5, which include creatine/creatinine, glucose, creatinine, citrate, carnitine, 2-oxoglutarate, succinate, hippurate, leucine, 1-methylnicotinamice (MNA), taurine, 3-hydroxybutyrate (3-HB), tryptophan, lysine, trigonelline, allantoin, formiate, acetoacetate (AcAc) and dimethylamine. From the changes in the metabolites, the affected pathways and aspects of metabolism were identified.
CONCLUSION: I. aquatica ethanolic extract increases metabolite levels such as creatinine/creatine, carnitine, MNA, trigonelline, leucine, lysine, 3-HB and decreases metabolite levels, including glucose and tricarboxylic acid (TCA) intermediates. This implies capabilities of I. aquatica ethanolic extract promoting glycolysis, gut microbiota and nicotinate/nicotinamide metabolism, improving the glomerular filtration rate (GFR) and reducing the β-oxidation rate. However, the administration of I. aquatica ethanolic extract has several drawbacks, such as unimproved changes in amino acid metabolism, especially in reducing branched chain amino acid (BCAA) synthesis pathways and lipid metabolism.

Matched MeSH terms: Gastrointestinal Microbiome/drug effects
Fulltext Efficacy of Whole Cell Inactivated Vibrio harveyi Vaccine against Vibriosis in a Marine Red Hybrid Tilapia (Oreochromis niloticus × O. mossambicus) Model

Abu Nor N, Zamri-Saad M, Md Yasin IS, Salleh A, Mustaffa-Kamal F, Matori MF, et al.

Vaccines (Basel), 2020 Dec 04;8(4).
PMID: 33291587 DOI: 10.3390/vaccines8040734

Vibrio harveyi causes vibriosis in various commercial marine fish species. The infection leads to significant economic losses for aquaculture farms, and vaccination is an alternative approach for the prevention and control of fish diseases for aquaculture sustainability. This study describes the use of formalin-killed Vibrio harveyi (FKVh) strain Vh1 as a vaccine candidate to stimulate innate and adaptive immunities against vibriosis in a marine red hybrid tilapia model. Tilapia are fast growing; cheap; resistant to diseases; and tolerant to adverse environmental conditions of fresh water, brackish water, and marine water and because of these advantages, marine red hybrid tilapia is a suitable candidate as a model to study fish diseases and vaccinations against vibriosis. A total of 180 healthy red hybrid tilapias were gradually adapted to the marine environment before being divided into two groups, with 90 fish in each group and were kept in triplicate with 30 fish per tank. Group 1 was vaccinated intraperitoneally with 100 µL of FKVh on week 0, and a booster dose was similarly administered on week 2. Group 2 was similarly injected with PBS. Skin mucus, serum, and gut lavage were collected weekly for enzyme-linked immunosorbent assay (ELISA) and a lysozyme activity assay from a total of 30 fish of each group. On week 4, the remaining 60 fish of Groups 1 and 2 were challenged with 108 cfu/fish of live Vibrio harveyi. The clinical signs were monitored while the survival rate was recorded for 48 h post-challenge. Vaccination with FKVh resulted in a significantly (p < 0.05) higher rate of survival (87%) compared to the control (20%). The IgM antibody titer and lysozyme activities of Group 1 were significantly (p < 0.05) higher than the unvaccinated Groups 2 in most weeks throughout the experiment. Therefore, the intraperitoneal exposure of marine red hybrid tilapia to killed V. harveyi enhanced the resistance and antibody response of the fish against vibriosis.

Matched MeSH terms: Gastrointestinal Microbiome
Fulltext Gut Dysbiosis and Intestinal Barrier Dysfunction: Potential Explanation for Early-Onset Colorectal Cancer

Ahmad Kendong SM, Raja Ali RA, Nawawi KNM, Ahmad HF, Mokhtar NM

Front Cell Infect Microbiol, 2021;11:744606.
PMID: 34966694 DOI: 10.3389/fcimb.2021.744606

Colorectal cancer (CRC) is a heterogeneous disease that commonly affects individuals aged more than 50 years old globally. Regular colorectal screening, which is recommended for individuals aged 50 and above, has decreased the number of cancer death toll over the years. However, CRC incidence has increased among younger population (below 50 years old). Environmental factors, such as smoking, dietary factor, urbanization, sedentary lifestyle, and obesity, may contribute to the rising trend of early-onset colorectal cancer (EOCRC) because of the lack of genetic susceptibility. Research has focused on the role of gut microbiota and its interaction with epithelial barrier genes in sporadic CRC. Population with increased consumption of grain and vegetables showed high abundance of Prevotella, which reduces the risk of CRC. Microbes, such as Fusobacterium nucleatum, Bacteroides fragilis and Escherichia coli deteriorate in the intestinal barrier, which leads to the infiltration of inflammatory mediators and chemokines. Gut dysbiosis may also occur following inflammation as clearly observed in animal model. Both gut dysbiosis pre- or post-inflammatory process may cause major alteration in the morphology and functional properties of the gut tissue and explain the pathological outcome of EOCRC. The precise mechanism of disease progression from an early stage until cancer establishment is not fully understood. We hypothesized that gut dysbiosis, which may be influenced by environmental factors, may induce changes in the genome, metabolome, and immunome that could destruct the intestinal barrier function. Also, the possible underlying inflammation may give impact microbial community leading to disruption of physical and functional role of intestinal barrier. This review explains the potential role of the interaction among host factors, gut microenvironment, and gut microbiota, which may provide an answer to EOCRC.

Matched MeSH terms: Gastrointestinal Microbiome*
Analysis of biofilms formation by cronobacter sp. During growth in infant formula milk

Aishah Faiqah Mohd Yusof, Prabhakaran P, Nur Diyana Azli, Norrakiah Abdullah Sani, Wan Syaidatul Aqma

Sains Malaysiana, 2017;46:903-908.

Pacifier nipples are in permanent contact with saliva and with the oral microflora therefore, act as a favoured site for the growth of biofilms. This research was conducted to identify the bacterial biofilms that has been found on the pacifiers that collected from local child nursery and to analyse the formation of biofilms by Cronobacter sp. during growth in infant formula milk. Pacifiers collected were analysed to obtain colony forming unit (CFU) and isolated bacteria were identified using several biochemical tests according to Bergey's Manual. Biofilm assay of three Cronobacter sp. were conducted using 24 wells microtiter plate and stained with 1% of crystal violet solution at different time interval: 6, 12, 18 and 24 h. The hydrophobicity of the bacterial cell suspension was evaluated using bacterial adhesion to hydrocarbons (BATH) method. Extracellular polymeric substances (EPS) analysis was done to identify percentage of carbohydrate and protein content by using phenol sulphuric acid method and Bradford method, respectively. The results obtained showed that the normal microflora bacteria were the most abundant microorganisms that were found on the pacifier with the main genus isolated was Staphylococcus sp., Enterobacteriaceae sp. and Clostridium sp. Based on biofilm and EPS analysis, Cronobacter sakazakii formed a strong biofilms after 18 h, with carbohydrate was identified as main component of EPS.

Matched MeSH terms: Gastrointestinal Microbiome
Gut bacteria of animals/pests living in polluted environments are a potential source of antibacterials

Akbar N, Siddiqui R, Sagathevan KA, Khan NA

Appl Microbiol Biotechnol, 2019 May;103(10):3955-3964.
PMID: 30941460 DOI: 10.1007/s00253-019-09783-2

The morbidity and mortality associated with bacterial infections have remained significant despite chemotherapeutic advances. With the emergence of drug-resistant bacterial strains, the situation has become a serious threat to the public health. Thus, there is an urgent need to identify novel antibacterials. The majority of antibiotics available in the market are produced by bacteria isolated from soil. However, the low-hanging fruit has been picked; hence, there is a need to mine bacteria from unusual sources. With this in mind, it is important to note that animals and pests such as cockroaches, snake, crocodiles, and water monitor lizard come across pathogenic bacteria regularly, yet flourish in contaminated environments. These species must have developed methods to defend themselves to counter pathogens. Although the immune system is known to possess antiinfective properties, gut bacteria of animals/pests may also offer a potential source of novel antibacterial agents, and it is the subject of this study. This paper discusses our current knowledge of bacteria isolated from land and marine animals with antibacterial properties and to propose untapped sources for the isolation of bacteria to mine potentially novel antibiotic molecules.

Matched MeSH terms: Gastrointestinal Microbiome*
Fulltext Gut bacteria of Cuora amboinensis (turtle) produce broad-spectrum antibacterial molecules

Akbar N, Khan NA, Sagathevan K, Iqbal M, Tawab A, Siddiqui R

Sci Rep, 2019 11 18;9(1):17012.
PMID: 31740685 DOI: 10.1038/s41598-019-52738-w

Antimicrobial resistance is a major threat to human health, hence there is an urgent need to discover antibacterial molecule(s). Previously, we hypothesized that microbial gut flora of animals are a potential source of antibacterial molecules. Among various animals, Cuora amboinensis (turtle) represents an important reptile species living in diverse ecological environments and feed on organic waste and terrestrial organisms and have been used in folk medicine. The purpose of this study was to mine turtle's gut bacteria for potential antibacterial molecule(s). Several bacteria were isolated from the turtle gut and their conditioned media were prepared. Conditioned media showed potent antibacterial activity against several Gram-positive (Bacillus cereus, Streptococcus pyogenes and methicillin-resistant Staphylococcus aureus) and Gram-negative (neuropathogenic Escherichia coli K1, Serratia marcescens, Pseudomonas aeruginosa, Salmonella enterica and Klebsiella pneumoniae) pathogenic bacteria. Conditioned media-mediated bactericidal activity was heat-resistant when treated at 95°C for 10 min. By measuring Lactate dehydrogenase release, the results showed that conditioned media had no effect on human cell viability. Tandem Mass Spectrometric analysis revealed the presence of various secondary metabolites, i.e., a series of known as well as novel N-acyl-homoserine lactones, several homologues of 4-hydroxy-2-alkylquinolines, and rhamnolipids, which are the signature metabolites of Pseudomonas species. These findings are significant and provide the basis for rational development of therapeutic interventions against bacterial infections.

Matched MeSH terms: Gastrointestinal Microbiome*
Fulltext Gut Bacteria of Water Monitor Lizard (Varanus salvator) Are a Potential Source of Antibacterial Compound(s)

Akbar N, Siddiqui R, Sagathevan K, Iqbal M, Khan NA

Antibiotics (Basel), 2019 Sep 24;8(4).
PMID: 31554316 DOI: 10.3390/antibiotics8040164

For the past few decades, there has been limited progress in the development of novel antibacterials. Previously, we postulated that the gut microbiota of animals residing in polluted environments are a forthcoming supply of antibacterials. Among various species, the water monitor lizard is an interesting species that feeds on organic waste and the carcass of wild animals. Gut microbiota of the water monitor lizard were sequestered, identified and cultivated in RPMI-1640 to produce conditioned medium (CM). Next, the antimicrobial properties of CM were evaluated versus a selection of Gram-negative (Escherichia coli K1, Serratia marcescens,Pseudomonas aeruginosa, Salmonella enterica and Klebsiella pneumoniae) and Gram-positive bacteria (Streptococcus pyogenes, methicillin-resistant Staphylococcus aureus, and Bacillus cereus). CM were partially characterized by heat inactivation at 95°C for 10 min and tested against P. aeruginosa and S. pyogenes. CM were also tested against immortalized human keratinocytes (HaCaT) cells lines. The results demonstrated that gut microbiota isolated from water monitor lizard produced molecules with remarkable bactericidal activities. To determine the identity of the active molecules, CM were subjected to Liquid Chromatography-Mass Spectrometry. Several molecules were identified belonging to the classes of flavonoids, terpenoids, alkaloids, polyhydroxy alkaloids, polyacetylenes, bisphenols, amides, oxylipin and pyrazine derivatives with known broad-spectrum antimicrobial, anti-tumour, anti-oxidant, anti-inflammatory, and analgesic attributes. Furthermore, the detailed analysis of these molecules could lead us to develop effective therapeutic antibacterials.

Matched MeSH terms: Gastrointestinal Microbiome
Gut bacteria of cockroaches are a potential source of antibacterial compound(s)

Akbar N, Siddiqui R, Iqbal M, Sagathevan K, Khan NA

Lett Appl Microbiol, 2018 May;66(5):416-426.
PMID: 29457249 DOI: 10.1111/lam.12867

Here, we hypothesized that the microbial gut flora of animals/pests living in polluted environments, produce substances to thwart bacterial infections. The overall aim of this study was to source microbes inhabiting unusual environmental niches for potential antimicrobial activity. Two cockroach species, Gromphadorhina portentosa (Madagascar) and Blaptica dubia (Dubia) were selected. The gut bacteria from these species were isolated and grown in RPMI 1640 and conditioned media were prepared. Conditioned media were tested against a panel of Gram-positive (Methicillin-resistant Staphylococcus aureus, Streptococcus pyogenes, Bacillus cereus) and Gram-negative (Escherichia coli K1, Salmonella enterica, Serratia marcescens, Pseudomonas aeruginosa, Klebsiella pneumoniae) bacteria, as well as the protist pathogen, Acanthamoeba castellanii. The results revealed that the gut bacteria of cockroaches produce active molecule(s) with potent antibacterial properties, as well as exhibit antiamoebic effects. However, heat-inactivation at 95°C for 10 min had no effect on conditioned media-mediated antibacterial and antiamoebic properties. These results suggest that bacteria from novel sources i.e. from the cockroach's gut produce molecules with bactericidal as well as amoebicidal properties that can ultimately lead to the development of therapeutic drugs.
SIGNIFICANCE AND IMPACT OF THE STUDY: The bacteria isolated from unusual dwellings such as the cockroaches' gut are a useful source of antibacterial and antiamoebal molecules. These are remarkable findings that will open several avenues in our search for novel antimicrobials from unique sources. Furthermore studies will lead to the identification of molecules to develop future antibacterials from insects.

Matched MeSH terms: Gastrointestinal Microbiome/physiology*
Gut bacteria of animals living in polluted environments exhibit broad-spectrum antibacterial activities

Akbar N, Siddiqui R, Sagathevan K, Khan NA

Int Microbiol, 2020 Nov;23(4):511-526.
PMID: 32124096 DOI: 10.1007/s10123-020-00123-3

Infectious diseases, in particular bacterial infections, are the leading cause of morbidity and mortality posing a global threat to human health. The emergence of antibiotic resistance has exacerbated the problem further. Hence, there is a need to search for novel sources of antibacterials. Herein, we explored gut bacteria of a variety of animals living in polluted environments for their antibacterial properties against multi-drug resistant pathogenic bacteria. A variety of species were procured including invertebrate species, Blaptica dubia (cockroach), Gromphadorhina portentosa (cockroach), Scylla serrata (crab), Grammostola rosea (tarantula), Scolopendra subspinipes (centipede) and vertebrate species including Varanus salvator (water monitor lizard), Malayopython reticulatus (python), Cuora amboinensis (tortoise), Oreochromis mossambicus (tilapia fish), Rattus rattus (rat), Gallus gallus domesticus (chicken) and Lithobates catesbeianus (frog). Gut bacteria of these animals were isolated and identified using microbiological, biochemical, analytical profiling index (API) and through molecluar identification using 16S rRNA sequencing. Bacterial conditioned media (CM) were prepared and tested against selected Gram-positive and Gram-negative pathogenic bacteria as well as human cells (HaCaT). The results revealed that CM exhibited significant broad-spectrum antibacterial activities. Upon heat inactivation, CM retained their antibacterial properties suggesting that this effect may be due to secondary metabolites or small peptides. CM showed minimal cytotoxicity against human cells. These findings suggest that gut bacteria of animals living in polluted environments produce broad-spectrum antibacterial molecule(s). The molecular identity of the active molecule(s) together with their mode of action is the subject of future studies which could lead to the rational development of novel antibacterial(s).

Matched MeSH terms: Gastrointestinal Microbiome/physiology*
Fulltext Gut Bacteria of Rattus rattus (Rat) Produce Broad-Spectrum Antibacterial Lipopeptides

Akbar N, Siddiqui R, Iqbal M, Sagathevan K, Kim KS, Habib F, et al.

ACS Omega, 2021 May 11;6(18):12261-12273.
PMID: 34056379 DOI: 10.1021/acsomega.1c01137

Among several animals, Rattus rattus (rat) lives in polluted environments and feeds on organic waste/small invertebrates, suggesting the presence of inherent mechanisms to thwart infections. In this study, we isolated gut bacteria of rats for their antibacterial activities. Using antibacterial assays, the findings showed that the conditioned media from selected bacteria exhibited bactericidal activities against Gram-negative (Escherichia coli K1, Klebsiella pneumoniae, Pseudomonas aeruginosa, Serratia marcescens, and Salmonella enterica) and Gram-positive (Bacillus cereus, methicillin-resistant Staphylococcus aureus, and Streptococcus pyogenes) pathogenic bacteria. The conditioned media retained their antibacterial properties upon heat treatment at boiling temperature for 10 min. Using MTT assays, the conditioned media showed minimal cytotoxic effects against human keratinocyte cells. Active conditioned media were subjected to tandem mass spectrometry, and the results showed that conditioned media from Bacillus subtilis produced a large repertoire of surfactin and iturin A (lipopeptides) molecules. To our knowledge, this is the first report of isolation of lipopeptides from bacteria isolated from the rat gut. In short, these findings are important and provide a platform to develop effective antibacterial drugs.

Matched MeSH terms: Gastrointestinal Microbiome
Fulltext Effects of an isoenergetic low Glycaemic Index (GI) diet on liver fat accumulation and gut microbiota composition in patients with non-alcoholic fatty liver disease (NAFLD): a study protocol of an efficacy mechanism evaluation

Al-Awadi A, Grove J, Taylor M, Valdes A, Vijay A, Bawden S, et al.

BMJ Open, 2021 10 07;11(10):e045802.
PMID: 34620653 DOI: 10.1136/bmjopen-2020-045802

INTRODUCTION: A Low Glycaemic Index (LGI) diet is a proposed lifestyle intervention in non-alcoholic fatty liver diseases (NAFLD) which is designed to reduce circulating blood glucose levels, hepatic glucose influx, insulin resistance and de novo lipogenesis. A significant reduction in liver fat content through following a 1-week LGI diet has been reported in healthy volunteers. Changes in dietary fat and carbohydrates have also been shown to alter gut microbiota composition and lead to hepatic steatosis through the gut-liver axis. There are no available trials examining the effects of an LGI diet on liver fat accumulation in patients with NAFLD; nor has the impact of consuming an LGI diet on gut microbiota composition been studied in this population. The aim of this trial is to investigate the effects of LGI diet consumption on liver fat content and its effects on gut microbiota composition in participants with NAFLD compared with a High Glycaemic Index (HGI) control diet.
METHODS AND ANALYSIS: A 2×2 cross-over randomised mechanistic dietary trial will allocate 16 participants with NAFLD to a 2-week either HGI or LGI diet followed by a 4-week wash-out period and then the LGI or HGI diet, alternative to that followed in the first 2 weeks. Baseline and postintervention (four visits) outcome measures will be collected to assess liver fat content (using MRI/S and controlled attenuation parameter-FibroScan), gut microbiota composition (using 16S RNA analysis) and blood biomarkers including glycaemic, insulinaemic, liver, lipid and haematological profiles, gut hormones levels and short-chain fatty acids.
ETHICS AND DISSEMINATION: Study protocol has been approved by the ethics committees of The University of Nottingham and East Midlands Nottingham-2 Research Ethics Committee (REC reference 19/EM/0291). Data from this trial will be used as part of a Philosophy Doctorate thesis. Publications will be in peer-reviewed journals.
TRIAL REGISTRATION NUMBER: NCT04415632.

Matched MeSH terms: Gastrointestinal Microbiome*
Fulltext Gut Microbiota Disruption in COVID-19 or Post-COVID Illness Association with severity biomarkers: A Possible Role of Pre / Pro-biotics in manipulating microflora

Alharbi KS, Singh Y, Hassan Almalki W, Rawat S, Afzal O, Alfawaz Altamimi AS, et al.

Chem Biol Interact, 2022 May 01;358:109898.
PMID: 35331679 DOI: 10.1016/j.cbi.2022.109898

Coronavirus disease (COVID-19), a coronavirus-induced illness attributed to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission, is thought to have first emerged on November 17, 2019. According to World Health Organization (WHO). COVID-19 has been linked to 379,223,560 documented occurrences and 5,693,245 fatalities globally as of 1st Feb 2022. Influenza A virus that has also been discovered diarrhea and gastrointestinal discomfort was found in the infected person, highlighting the need of monitoring them for gastro intestinal tract (GIT) symptoms regardless of whether the sickness is respiration related. The majority of the microbiome in the intestines is Firmicutes and Bacteroidetes, while Bacteroidetes, Proteobacteria, and Firmicutes are found in the lungs. Although most people overcome SARS-CoV-2 infections, many people continue to have symptoms months after the original sickness, called Long-COVID or Post COVID. The term "post-COVID-19 symptoms" refers to those that occur with or after COVID-19 and last for more than 12 weeks (long-COVID-19). The possible understanding of biological components such as inflammatory, immunological, metabolic activity biomarkers in peripheral blood is needed to evaluate the study. Therefore, this article aims to review the informative data that supports the idea underlying the disruption mechanisms of the microbiome of the gastrointestinal tract in the acute COVID-19 or post-COVID-mediated elevation of severity biomarkers.

Matched MeSH terms: Gastrointestinal Microbiome*
Antibacterial activity of selected invertebrate species

Ali SM, Siddiqui R, Sagathevan KA, Khan NA

Folia Microbiol (Praha), 2021 Apr;66(2):285-291.
PMID: 33704690 DOI: 10.1007/s12223-021-00860-6

The evolution of multiple-drug resistant bacteria is contributing to the global antimicrobial crisis, hence driving us to search for novel antimicrobial(s). Among animals, invertebrates represent up to 80% of all known species suggesting their wide distribution. Despite their ubiquitous and plentiful nature, they have been largely unexplored as potential source of antibacterials. In this study, we selected a broad range of invertebrates from terrestrial and marine environments and tested their lysates for antibacterial activity against methicillin-resistant Staphylococcus aereus (MRSA) and neuropathogenic Escherichia coli K1. Cockroaches, centipedes, tarantulas, prawns, lobster, and mud crabs showed antibacterial activity with selected lysates exhibiting more than 90% bactericidal effects. The red-headed centipede's hemolymph showed 90% and 50% bacteriostatic activity against MRSA and E. coli K1, respectively. Tarantula's body extracts exhibited antibacterial activity against MRSA and E. coli K1. Gut extracts of tiger prawn exhibited more than 90% bacteriostatic activity against both bacteria. The selected lobster and mud crab extract exhibited up to 90% growth inhibitory activity against MRSA. Overall, these results showed that selected invertebrates are an untapped source of broad-spectrum antibacterial activity and suggest the presence of biologically active molecules.

Matched MeSH terms: Gastrointestinal Microbiome
Lactobacillus probiotics restore vaginal and gut microbiota of pregnant women with vaginal candidiasis

Ang XY, Roslan NS, Ahmad N, Yusof SM, Abdullah N, Nik Ab Rahman NN, et al.

Benef Microbes, 2023 Nov 23;14(5):421-431.
PMID: 38350486 DOI: 10.1163/18762891-20220103

The development of probiotics has now included the areas along the gut-vaginal axis. We thus aimed to investigate the effects of lactobacilli probiotic to modulate and restore vaginal and gut microbiota of pregnant women with vaginal candidiasis (VC). A randomised, double-blind and placebo-controlled study was performed in 78 pregnant women with VC. Patients were randomised to either the probiotic (SynForU-HerCare) or placebo which were administered at baseline and continued for 8-weeks (two capsules/day of 9.5 log cfu/capsule). Microbiota profiles were assessed at time points of weeks-0, 4 and 8 for high vaginal swab and faecal samples. Shannon diversity index showed that after 8-weeks amid VC, a shift in microbial community compositional changes occurred in the high vaginal region at both genus (P=0.025) and species (P=0.044) levels, where the administration of probiotic prevented such a shift. These changes were mainly attributed to a decreased in abundance of Lactobacillus (P=0.042) accompanied by increased abundance of Prevotella (P=0.002) and Atopobium (P=0.002) in the placebo group while the probiotic group remained unchanged over time. The administration of probiotics also prevented a reduced abundance of faecal phylum Firmicutes after 8-weeks as seen in the placebo group (P<0.0001), which also showed reduction at subsequent taxonomic levels of class, family, genera and species. VC has not only altered the microbiota of vagina regions but also gut microbiota profiles, causing lessening of gut microbiota that are crucial for gut nutrient availability, protection and immunity. The administration of lactobacilli probiotics has prevented such a shift, leading to better modulated gut and vaginal microenvironment amid VC. The study was registered at ClinicalTrials.gov: identifier number NCT03940612.

Matched MeSH terms: Gastrointestinal Microbiome*
Gut Microbiota and Epilepsy: A Systematic Review on Their Relationship and Possible Therapeutics

Arulsamy A, Tan QY, Balasubramaniam V, O'Brien TJ, Shaikh MF

ACS Chem Neurosci, 2020 Nov 04;11(21):3488-3498.
PMID: 33064448 DOI: 10.1021/acschemneuro.0c00431

Dysbiosis of gut microbiota may lead to a range of diseases including neurological disorders. Thus, it is hypothesized that regulation of the intestinal microbiota may prevent or treat epilepsy. The purpose of this systematic review is to evaluate the evidence investigating the relationship between gut microbiota and epilepsy and possible interventions. A systematic review of the literature was done on four databases (PubMed, Scopus, EMBASE, and Web of Science). Study selection was restricted to original research articles while following the PRISMA guidelines. Six studies were selected. These studies cohesively support the interaction between gut microbiota and epileptic seizures. Gut microbiota analysis identified increases in Firmicutes, Proteobacteria, Verrucomicrobia, and Fusobacteria with decreases in Bacteroidetes and Actinobacteria in epileptic patients. Ketogenic diet, probiotics, and fecal microbiota transplantation (FMT) improved the dysbiosis of the gut microbiota and seizure activity. However, the studies either had a small sample size, lack of subject variability, or short study or follow-up period, which may question their reliability. Nevertheless, these limited studies conclusively suggest that gut microbiota diversity and dysbiosis may be involved in the pathology of epilepsy. Future studies providing more reliable and in depth insight into the gut microbial community will spark promising alternative therapies to current epilepsy treatment.

Matched MeSH terms: Gastrointestinal Microbiome
Short Chain Fatty Acids: Fundamental mediators of the gut-lung axis and their involvement in pulmonary diseases

Ashique S, De Rubis G, Sirohi E, Mishra N, Rihan M, Garg A, et al.

Chem Biol Interact, 2022 Dec 01;368:110231.
PMID: 36288778 DOI: 10.1016/j.cbi.2022.110231

The human microbiota is fundamental to correct immune system development and balance. Dysbiosis, or microbial content alteration in the gut and respiratory tract, is associated with immune system dysfunction and lung disease development. The microbiota's influence on human health and disease is exerted through the abundance of metabolites produced by resident microorganisms, where short-chain fatty acids (SCFAs) represent the fundamental class. SCFAs are mainly produced by the gut microbiota through anaerobic fermentation of dietary fibers, and are known to influence the homeostasis, susceptibility to and outcome of many lung diseases. This article explores the microbial species found in healthy human gastrointestinal and respiratory tracts. We investigate factors contributing to dysbiosis in lung illness, and the gut-lung axis and its association with lung diseases, with a particular focus on the functions and mechanistic roles of SCFAs in these processes. The key focus of this review is a discussion of the main metabolites of the intestinal microbiota that contribute to host-pathogen interactions: SCFAs, which are formed by anaerobic fermentation. These metabolites include propionate, acetate, and butyrate, and are crucial for the preservation of immune homeostasis. Evidence suggests that SCFAs prevent infections by directly affecting host immune signaling. This review covers the various and intricate ways through which SCFAs affect the immune system's response to infections, with a focus on pulmonary diseases including chronic obstructive pulmonary diseases, asthma, lung cystic fibrosis, and tuberculosis. The findings reviewed suggest that the immunological state of the lung may be indirectly influenced by elements produced by the gut microbiota. SCFAs represent valuable potential therapeutic candidates in this context.

Matched MeSH terms: Gastrointestinal Microbiome*

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