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Proteomic profiling of clinical and environmental strains of Pseudomonas aeruginosa

Liew SM, Puthucheary SD, Rajasekaram G, Chai HC, Chua KH

Mol Biol Rep, 2021 Mar;48(3):2325-2333.
PMID: 33728559 DOI: 10.1007/s11033-021-06262-8

Pseudomonas aeruginosa is a ubiquitous bacterium, which is able to change its physiological characteristics in response to different habitats. Environmental strains are presumably less pathogenic than clinical strains and whether or not the clinical strains originate from the environment or through inter-host transmission remains poorly understood. To minimize the risk of infection, a better understanding of proteomic profiling of P. aeruginosa is necessary for elucidating the correlation between environmental and clinical strains. Based on antimicrobial susceptibility and patterns of virulence, we selected 12 clinical and environmental strains: (i) environmental, (ii) multidrug resistant (MDR) clinical and (iii) susceptible clinical strains. Whole-cell protein was extracted from each strain and subjected to two-dimensional differential gel electrophoresis (2-D DIGE) and liquid chromatography tandem mass spectrometry quadrupole time-of-flight (LC-MS QTOF). All 12 strains were clustered into 3 distinct groups based on their variance in protein expression. A total of 526 matched spots were detected and four differentially expressed protein spots (p < 0.05) were identified and all differential spots were downregulated in MDR strain J3. Upregulation of chitin binding and BON domain proteins was present in the environmental and some MDR strains, whereas the clinical strains exhibited distinct proteomic profiles with increased expression of serine protein kinase and arginine/ornithine transport ATP-binding proteins. Significant difference in expression was observed between susceptible clinical and MDR strains, as well as susceptible clinical and environmental strains. Transition from an environmental saprophyte to a clinical strain could alter its physiological characteristics to further increase its adaptation.

Matched MeSH terms: Environmental Microbiology*
Fulltext An Analysis Review of Detection Coronavirus Disease 2019 (COVID-19) Based on Biosensor Application

Taha BA, Al Mashhadany Y, Hafiz Mokhtar MH, Dzulkefly Bin Zan MS, Arsad N

Sensors (Basel), 2020 Nov 26;20(23).
PMID: 33256085 DOI: 10.3390/s20236764

Timely detection and diagnosis are essentially needed to guide outbreak measures and infection control. It is vital to improve healthcare quality in public places, markets, schools and airports and provide useful insights into the technological environment and help researchers acknowledge the choices and gaps available in this field. In this narrative review, the detection of coronavirus disease 2019 (COVID-19) technologies is summarized and discussed with a comparison between them from several aspects to arrive at an accurate decision on the feasibility of applying the best of these techniques in the biosensors that operate using laser detection technology. The collection of data in this analysis was done by using six reliable academic databases, namely, Science Direct, IEEE Xplore, Scopus, Web of Science, Google Scholar and PubMed. This review includes an analysis review of three highlights: evaluating the hazard of pandemic COVID-19 transmission styles and comparing them with Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) to identify the main causes of the virus spreading, a critical analysis to diagnose coronavirus disease 2019 (COVID-19) based on artificial intelligence using CT scans and CXR images and types of biosensors. Finally, we select the best methods that can potentially stop the propagation of the coronavirus pandemic.

Matched MeSH terms: Environmental Microbiology
First Report of Environmental Isolation of Exophiala spp. in Malaysia

Jayaram M, Nagao H

Curr Microbiol, 2020 Oct;77(10):2915-2924.
PMID: 32661678 DOI: 10.1007/s00284-020-02109-w

The opportunistic pathogen Exophiala dermatitidis has been frequently isolated from tropical regions of the world. However, there is no report of environmental isolation of Exophiala spp. from Malaysia. The information regarding the ecology of this microbe is important for a better understanding of the opportunism. This study aims to conduct a survey of natural distribution of Exophiala spp. in Malaysia. Forty-seven strains of Exophiala-like was isolated by using selective media. These isolates from the fields were molecularly identified based on the ITS region. The biochemical activity of these microbes was tested by conducting various tests, i.e. DNase test, proteinase activity, and urea hydrolysis. Overall, 22 strains of E. dermatitidis were successfully obtained and identified from burnt tree bark, oil dripped soil sample, hot spring biofilm, railway track stones, tar road contaminated with petrol hydrocarbon, drain and deep mud of Sungai Pinang besides the new discovery from pigeon droppings. A single strain of E. heteromorpha was identified from tar road contaminated with petrol hydrocarbon. Genotypes of the isolated E. dermatitidis were identified by the neighbor-joining tree and grouped into Genotype A, A2 and B. The existence of new Genotype A4 was confirmed by a similar cladogram position in both neighbor-joining and maximum likelihood tree. The survival of E. dermatitidis in the hydrocarbon contaminated environment was studied by supplying engine oil and observing the growth pattern. The results of this study suggest that the opportunistic Exophiala spp. was isolated from nutrient limited and harsh conditions in the natural environment.

Matched MeSH terms: Environmental Microbiology*
Identification of Antibacterial Molecule(s) from Animals Living in Polluted Environments

Winnie FYM, Siddiqui R, Sagathevan K, Khan NA

Curr Pharm Biotechnol, 2020;21(5):425-437.
PMID: 31577204 DOI: 10.2174/1389201020666191002153435

BACKGROUND: Snakes feed on germ-infested rodents, while water monitor lizards thrive on rotten matter in unhygienic conditions. We hypothesize that such creatures survive the assault of superbugs and are able to fend off disease by producing antimicrobial substances. In this study, we investigated the potential antibacterial activity of sera/lysates of animals living in polluted environments.
METHODS: Snake (Reticulatus malayanus), rats (Rattus rattus), water monitor lizard (Varanus salvator), frog (Lithobates catesbeianus), fish (Oreochromis mossambicus), chicken (Gallus gallus domesticus), and pigeon (Columba livia) were dissected and their organ lysates/sera were collected. Crude extracts were tested for bactericidal effects against neuropathogenic E. coli K1, methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pyogenes, Pseudomonas aeruginosa, Bacillus cereus and Klebsiella pneumoniae. To determine whether lysates/sera protect human cells against bacterialmediated damage, cytotoxicity assays were performed by measuring lactate dehydrogenase release as an indicator of cell death. Lysates/sera were partially characterized using heat-treatment and pronasetreatment and peptide sequences were determined using the Liquid Chromatography Mass Spectrometry (LC-MS).
RESULTS: Snake and water monitor lizard sera exhibited potent broad-spectrum bactericidal effects against all bacteria tested. Heat inactivation and pronase-treatment inhibited bactericidal effects indicating that activity is heat-labile and pronase-sensitive suggesting that active molecules are proteinaceous in nature. LCMS analyses revealed the molecular identities of peptides.
CONCLUSION: The results revealed that python that feeds on germ-infested rodents and water monitor lizards that feed on rotten organic waste possess antibacterial activity in a heat-sensitive manner and several peptides were identified. We hope that the discovery of antibacterial activity in the sera of animals living in polluted environments will stimulate research in finding antibacterial agents from unusual sources as this has the potential for the development of novel strategies in the control of infectious diseases.

Matched MeSH terms: Environmental Microbiology/standards*
Application of Phenotype Microarray for Profiling Carbon Sources Utilization between Biofilm and Non-Biofilm of Pseudomonas aeruginosa from Clinical Isolates

Ismail NS, Subbiah SK, Taib NM

Curr Pharm Biotechnol, 2020;21(14):1539-1550.
PMID: 32598252 DOI: 10.2174/1389201021666200629145217

BACKGROUND: This is the fastest work in obtaining the metabolic profiles of Pseudomonas aeruginosa in order to combat the infection diseases which leads to high morbidity and mortality rates. Pseudomonas aeruginosa is a high versatility of gram-negative bacteria that can undergo aerobic and anaerobic respiration. Capabilities in deploying different carbon sources, energy metabolism and regulatory system, ensure the survival of this microorganism in the diverse environment condition. Determination of differences in carbon sources utilization among biofilm and non-biofilm of Pseudomonas aeruginosa provides a platform in understanding the metabolic activity of the microorganism.
METHODS: The study was carried out from September 2017 to February 2019. Four archive isolates forming strong and intermediate biofilm and non-biofilms producer were subcultured from archive isolates. ATCC 27853 P. aeruginosa was used as a negative control or non-biofilm producing microorganism. Biofilm formation was confirmed by Crystal Violet Assay (CVA) and Congo Red Agar (CRA). Metabolic profiles of the biofilm and non-biofilms isolates were determined by phenotype microarrays (Biolog Omnilog).
RESULTS AND DISCUSSION: In this study, Pseudomonas aeruginosa biofilm isolates utilized uridine, L-threonine and L-serine while non-biofilm utilized adenosine, inosine, monomethyl, sorbic acid and succinamic acid.
CONCLUSION: The outcome of this result will be used for future studies to improve detection or inhibit the growth of P. aeruginosa biofilm and non-biofilm respectively.

Matched MeSH terms: Environmental Microbiology
Environmental control of Vibrio spp. abundance and community structure in tropical waters

Wong YY, Lee CW, Bong CW, Lim JH, Narayanan K, Sim EUH

FEMS Microbiol Ecol, 2019 11 01;95(11).
PMID: 31688899 DOI: 10.1093/femsec/fiz176

We measured Vibrio spp. distribution and community profile in the tropical estuary of Port Klang and coastal water of Port Dickson, Malaysia. Vibrio spp. abundance ranged from 15 to 2395 colony forming units mL-1, and was driven by salinity and chlorophyll a (Chl a) concentration. However, the effect of salinity was pronounced only when salinity was <20 ppt. A total of 27 Vibrio spp. were identified, and theVibrio spp. community at Port Dickson was more diverse (H' = 1.94 ± 0.21). However species composition between Port Dickson and Port Klang were similar. Two frequently occurring Vibrio spp. were V. owensii and V. rotiferianus, which exhibited relatively higher growth rates (ANCOVA: F > 4.338, P < 0.05). Co-culture experiments between fast- and slow-growing Vibrio spp. revealed that fast-growing Vibrio spp. (r-strategists) were overwhelmed by slower-growing Vibrio spp. (K-strategists) when nutrient conditions were set towards oligotrophy. In response to resource availability, the intrinsic growth strategy of each Vibrio spp. determined its occurrence and the development of Vibrio spp. community composition.

Matched MeSH terms: Environmental Microbiology*
Molecular epidemiology of Clostridium difficile isolated from piglets

Putsathit P, Neela VK, Joseph NMS, Ooi PT, Ngamwongsatit B, Knight DR, et al.

Vet Microbiol, 2019 Oct;237:108408.
PMID: 31585650 DOI: 10.1016/j.vetmic.2019.108408

Information on the epidemiology of C. difficile infection (CDI) in South-East Asian countries is limited, as is data on possible animal reservoirs of C. difficile in the region. We investigated the prevalence and molecular epidemiology of C. difficile in piglets and the piggery environment in Thailand and Malaysia. Piglet rectal swabs (n = 224) and piggery environmental specimens (n = 23) were collected between 2015 and 2016 from 11 farms located in Thailand and Malaysia. All specimens were tested for the presence of C. difficile with toxigenic culture. PCR assays were performed on isolates to determine the ribotype (RT), and the presence of toxin genes. Whole genome sequencing was used on a subset of isolates to determine the evolutionary relatedness of RT038 (the most prevalent RT identified) common to pigs and humans from Thailand and Indonesia. C. difficile was recovered from 35% (58/165) and 92% (54/59) of the piglets, and 89% (8/9) and 93% (13/14) of the environmental specimens from Thailand and Malaysia, respectively. All strains from Thailand, and 30 strains from Malaysia (23 piglet and 7 environmental isolates) were non-toxigenic. To our knowledge, this is the first and only report with a complete lack of toxigenic C. difficile among piglets, a feature which could have a protective effect on the host. The most common strain belonged to RT038 (ST48), accounting for 88% (51/58) of piglet and 78% (7/9) of environmental isolates from Thailand, and all 30 isolates tested from Malaysia. Piglet RT038 isolates from Thailand and Malaysia differed by only 18 core-genome single nucleotide variants (cgSNVs) and both were, on average, 30 cgSNVs different from the human strains from Thailand and Indonesia, indicating a common ancestor in the last two decades.

Matched MeSH terms: Environmental Microbiology
Fulltext Genetic diversity of toxigenic Vibrio cholerae O1 from Sabah, Malaysia 2015

Zaw MT, Emran NA, Ibrahim MY, Suleiman M, Awang Mohd TA, Yusuff AS, et al.

J Microbiol Immunol Infect, 2019 Aug;52(4):563-570.
PMID: 29428381 DOI: 10.1016/j.jmii.2018.01.003

BACKGROUND: Cholera is an important health problem in Sabah, a Malaysian state in northern Borneo; however, Vibrio cholerae in Sabah have never been characterized. Since 2002, serogroup O1 strains having the traits of both classical and El Tor biotype, designated as atypical El Tor biotype, have been increasingly reported as the cause of cholera worldwide. These variants are believed to produce clinically more severe disease like classical strains.
PURPOSE: The purpose of this study is to investigate the genetic diversity of V.cholerae in Sabah and whether V.cholerae in Sabah belong to atypical El Tor biotype.
METHODS: ERIC-PCR, a DNA fingerprinting method for bacterial pathogens based on the enterobacterial repetitive intergenic consensus sequence, was used to study the genetic diversity of 65 clinical V.cholerae O1 isolates from 3 districts (Kudat, Beluran, Sandakan) in Sabah and one environmental isolate from coastal sea water in Kudat district. In addition, we studied the biotype-specific genetic traits in these isolates to establish their biotype.
RESULTS: Different fingerprint patterns were seen in isolates from these three districts but one of the patterns was seen in more than one district. Clinical isolates and environmental isolate have different patterns. In addition, Sabah isolates harbor genetic traits specific to both classical biotype (ctxB-1, rstRCla) and El Tor biotype (rstRET, rstC, tcpAET, rtxC, VC2346).
CONCLUSION: This study revealed that V.cholerae in Sabah were genetically diverse and were atypical El Tor strains. Fingerprint patterns of these isolates will be useful in tracing the origin of this pathogen in the future.

Matched MeSH terms: Environmental Microbiology
An outbreak of leptospirosis among reserve military recruits, Hulu Perdik, Malaysia

Neela VK, Azhari NN, Joseph N, Mimie NP, Ramli SNA, Mustapha NF, et al.

Eur J Clin Microbiol Infect Dis, 2019 Mar;38(3):523-528.
PMID: 30680558 DOI: 10.1007/s10096-018-03450-6

Here, we investigated an outbreak of leptospirosis among reserve military recruits that occurred following a survival exercise in the Hulu Perdik forest within the Hulu Langat district, Kuala Lumpur, Malaysia. Blood samples from the 12 patients that presented symptoms for febrile illness on clinical examination were subjected to laboratory investigation, comprising Lepto IgM rapid test, IgM ELISA, and microscopic agglutination test (MAT). All these patients were interviewed for possible risk factors for leptospirosis. Rodent trapping and environmental sampling for possible isolation of leptospires in the outbreak site was performed. The isolated leptospires were genetically characterized and investigated for the potential epidemiological link with human leptospirosis. Among the 12 patients, two (2/12; 16.6%) were confirmed positive for leptospirosis by microscopic agglutination test (MAT with titers 400-800; serovar autumnalis and hardjobovis). Two Leptospira species from rodents (L. interrogans and L. borgpetersenii) and two from the environment (L. kmetyi and L. wolffii) were identified. The possible epidemiological link between human serovars and animal Leptospira species indicates rodents as the potential reservoir while the environment (soil and water) serves as a transmission route. This investigation highlights the robust presence of pathogenic leptospires on Malaysian environment and rodents which may present the risk of infection, especially among high-risk individuals. Hence, occupational risk individuals are cautioned to observe appropriate preventive measures including prophylaxis and seek immediate medical attention for any illness following similar activities.

Matched MeSH terms: Environmental Microbiology
Fulltext Association of some Campylobacter jejuni with Pseudomonas aeruginosa biofilms increases attachment under conditions mimicking those in the environment

Teh AHT, Lee SM, Dykes GA

PLoS One, 2019;14(4):e0215275.
PMID: 30970009 DOI: 10.1371/journal.pone.0215275

Campylobacter jejuni is a microaerophilic bacterial species which is a major food-borne pathogen worldwide. Attachment and biofilm formation have been suggested to contribute to the survival of this fastidious bacteria in the environment. In this study the attachment of three C. jejuni strains (C. jejuni strains 2868 and 2871 isolated from poultry and ATCC 33291) to different abiotic surfaces (stainless steel, glass and polystyrene) alone or with Pseudomonas aeruginosa biofilms on them, in air at 25°C and under static or flow conditions, were investigated using a modified Robbins Device. Bacteria were enumerated and scanning electron microscopy was carried out. The results indicated that both C. jejuni strains isolated from poultry attached better to Pseudomonas aeruginosa biofilms on abiotic surfaces than to the surfaces alone under the different conditions tested. This suggests that biofilms of other bacterial species may passively protect C. jejuni against shear forces and potentially oxygen stress which then contribute to their persistence in environments which are detrimental to them. By contrast the C. jejuni ATCC 33291 strain did not attach differentially to P. aeruginosa biofilms, suggesting that different C. jejuni strains may have alternative strategies for persistence in the environment. This study supports the hypothesis that C. jejuni do not form biofilms per se under conditions they encounter in the environment but simply attach to surfaces or biofilms of other species.

Matched MeSH terms: Environmental Microbiology
Cupriavidus malaysiensis sp. nov., a novel poly(3-hydroxybutyrate-co-4-hydroxybutyrate) accumulating bacterium isolated from the Malaysian environment

Ramachandran H, Shafie NAH, Sudesh K, Azizan MN, Majid MIA, Amirul AA

Antonie Van Leeuwenhoek, 2018 Mar;111(3):361-372.
PMID: 29022146 DOI: 10.1007/s10482-017-0958-8

Bacterial classification on the basis of a polyphasic approach was conducted on three poly(3 hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] accumulating bacterial strains that were isolated from samples collected from Malaysian environments; Kulim Lake, Sg. Pinang river and Sg. Manik paddy field. The Gram-negative, rod-shaped, motile, non-sporulating and non-fermenting bacteria were shown to belong to the genus Cupriavidus of the Betaproteobacteria on the basis of their 16S rRNA gene sequence analyses. The sequence similarity value with their near phylogenetic neighbour, Cupriavidus pauculus LMG3413T, was 98.5%. However, the DNA-DNA hybridization values (8-58%) and ribotyping analysis both enabled these strains to be differentiated from related Cupriavidus species with validly published names. The RiboPrint patterns of the three strains also revealed that the strains were genetically related even though they displayed a clonal diversity. The major cellular fatty acids detected in these strains included C15:0 ISO 2OH/C16:1 ω7c, hexadecanoic (16:0) and cis-11-octadecenoic (C18:1 ω7c). Their G+C contents ranged from 68.0 to 68.6 mol%, and their major isoprenoid quinone was Ubiquinone Q-8. Of these three strains, only strain USMAHM13 (= DSM 25816 = KCTC 32390) was discovered to exhibit yellow pigmentation that is characteristic of the carotenoid family. Their assembled genomes also showed that the three strains were not identical in terms of their genome sizes that were 7.82, 7.95 and 8.70 Mb for strains USMAHM13, USMAA1020 and USMAA2-4, respectively, which are slightly larger than that of Cupriavidus necator H16 (7.42 Mb). The average nucleotide identity (ANI) results indicated that the strains were genetically related and the genome pairs belong to the same species. On the basis of the results obtained in this study, the three strains are considered to represent a novel species for which the name Cupriavidus malaysiensis sp. nov. is proposed. The type strain of the species is USMAA1020T (= DSM 19416T = KCTC 32390T).

Matched MeSH terms: Environmental Microbiology*
Fulltext Genome sequence of Streptomyces gilvigriseus MUSC 26T isolated from mangrove forest

Ser HL, Tan WS, Mutalib NA, Yin WF, Chan KG, Goh BH, et al.

Braz J Microbiol, 2018 02 02;49(2):207-209.
PMID: 29428207 DOI: 10.1016/j.bjm.2017.04.012

Streptomycetes remain as one of the important sources for bioactive products. Isolated from the mangrove forest, Streptomyces gilvigriseus MUSC 26T was previously characterised as a novel streptomycete. The high quality draft genome of MUSC 26T contained 5,213,277bp with G+C content of 73.0%. Through genome mining, several gene clusters associated with secondary metabolites production were revealed in the genome of MUSC 26T. These findings call for further investigations into the potential exploitation of the strain for production of pharmaceutically important compounds.

Matched MeSH terms: Environmental Microbiology*
Fulltext High Occurrence of Staphylococcus aureus Isolated from Fitness Equipment from Selected Gymnasiums

Maurice Bilung L, Tahar AS, Kira R, Mohd Rozali AA, Apun K

J Environ Public Health, 2018;2018:4592830.
PMID: 30245728 DOI: 10.1155/2018/4592830

Introduction: Staphylococcus aureus is a leading cause of cutaneous bacterial infection involving community.
Methods: In this study, a total of 42 swab samples were collected from the surface of various fitness equipment such as back machines, exercise mats, dip stations, dumbbells, and treadmills. Identification of the bacterial isolates was conducted using biochemical tests and further analysed molecularly using the PCR method targeting nuc gene (270 bp). The nuc gene encodes for the thermonuclease enzyme, a virulent factor of S. aureus.
Results: The findings showed 31 out of 42 swab samples (73.81%) were positive with S. aureus.
Conclusion: This study showed that gymnasium equipment is a potential reservoir for S. aureus and might play an important role in transmitting the pathogen to humans.
Objective: This study was undertaken to assess the presence of S. aureus on the surface of fitness equipment from selected gymnasiums in Kuching and Kota Samarahan, Sarawak (Malaysia).

Matched MeSH terms: Environmental Microbiology*
Fulltext Toxic effect of high concentration of sonochemically synthesized polyvinylpyrrolidone-coated silver nanoparticles on Citrobacter sp. A1 and Enterococcus sp. C1

Lau CP, Abdul-Wahab MF, Jaafar J, Chan GF, Abdul Rashid NA

J Microbiol Immunol Infect, 2017 Aug;50(4):427-434.
PMID: 26427880 DOI: 10.1016/j.jmii.2015.08.004

BACKGROUND/PURPOSE: Currently, silver nanoparticles (AgNPs) have gained importance in various industrial applications. However, their impact upon release into the environment on microorganisms remains unclear. The aim of this study was to analyze the effect of polyvinylpyrrolidone-capped AgNPs synthesized in this laboratory on two bacterial strains isolated from the environment, Gram-negative Citrobacter sp. A1 and Gram-positive Enterococcus sp. C1.
METHODS: Polyvinylpyrrolidone-capped AgNPs were synthesized by ultrasound-assisted chemical reduction. Characterization of the AgNPs involved UV-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and energy dispersive X-ray spectroscopy. Citrobacter sp. A1 and Enterococcus sp. C1 were exposed to varying concentrations of AgNPs, and cell viability was determined. Scanning electron microscopy was performed to evaluate the morphological alteration of both species upon exposure to AgNPs at 1000 mg/L.
RESULTS: The synthesized AgNPs were spherical in shape, with an average particle size of 15 nm. The AgNPs had different but prominent effects on either Citrobacter sp. A1 or Enterococcus sp. C1. At an AgNP concentration of 1000 mg/L, Citrobacter sp. A1 retained viability for 6 hours, while Enterococcus sp. C1 retained viability only for 3 hours. Citrobacter sp. A1 appeared to be more resistant to AgNPs than Enterococcus sp. C1. The cell wall of both strains was found to be morphologically altered at that concentration.
CONCLUSION: Minute and spherical AgNPs significantly affected the viability of the two bacterial strains selected from the environment. Enterococcus sp. C1 was more vulnerable to AgNPs, probably due to its cell wall architecture and the absence of silver resistance-related genes.

Matched MeSH terms: Environmental Microbiology
Characterization of an autotrophic bioreactor microbial consortium degrading thiocyanate

Watts MP, Spurr LP, Gan HM, Moreau JW

Appl Microbiol Biotechnol, 2017 Jul;101(14):5889-5901.
PMID: 28510801 DOI: 10.1007/s00253-017-8313-6

Thiocyanate (SCN-) forms as a by-product of cyanidation during gold ore processing and can be degraded by a variety of microorganisms utilizing it as an energy, nitrogen, sulphur and/or carbon source. In complex consortia inhabiting bioreactor systems, a range of metabolisms are sustained by SCN- degradation; however, despite the addition or presence of labile carbon sources in most bioreactor designs to date, autotrophic bacteria have been found to dominate key metabolic functions. In this study, we cultured an autotrophic SCN--degrading consortium directly from gold mine tailings. In a batch-mode bioreactor experiment, this consortium degraded 22 mM SCN-, accumulating ammonium (NH4+) and sulphate (SO42-) as the major end products. The consortium consisted of a diverse microbial community comprised of chemolithoautotrophic members, and despite the absence of an added organic carbon substrate, a significant population of heterotrophic bacteria. The role of eukaryotes in bioreactor systems is often poorly understood; however, we found their 18S rRNA genes to be most closely related to sequences from bacterivorous Amoebozoa. Through combined chemical and phylogenetic analyses, we were able to infer roles for key microbial consortium members during SCN- biodegradation. This study provides a basis for understanding the behaviour of a SCN- degrading bioreactor under autotrophic conditions, an anticipated approach to remediating SCN- at contemporary gold mines.

Matched MeSH terms: Environmental Microbiology*
Fulltext Genetic diversity of Enterococcus faecalis isolated from environmental, animal and clinical sources in Malaysia

Daniel DS, Lee SM, Gan HM, Dykes GA, Rahman S

J Infect Public Health, 2017 02 21;10(5):617-623.
PMID: 28254461 DOI: 10.1016/j.jiph.2017.02.006

Enterococcus faecalis ranks as one of the leading causes of nosocomial infections. A strong epidemiological link has been reported between E. faecalis inhabiting animals and environmental sources. This study investigates the genetic diversity, antibiotic resistance and virulence determinants in E. faecalis from three sources in Malaysia. A total of 250 E. faecalis isolates were obtained consisting of 120 isolates from farm animals, 100 isolates from water sources and 30 isolates from hospitalized patients. Pulse-field gel electrophoresis-typing yielded 63 pulsotypes, with high diversity observed in all sources (D=≥0.901). No pulsotype was common to all the three sources. Each patient room had its own unique PFGE pattern which persisted after six months. Minimum inhibitory concentrations of Vancomycin, Gentamicin, Penicillin, Tetracycline, Nitrofurantoin, Levofloxacin, Ciprofloxacin and Fosfomycin were evaluated. Resistance to Tetracycline was most prevalent in isolates from farm animals (62%) and water sources (49%). Water isolates (86%) had a higher prevalence of the asa1 gene, which encodes for aggregation substance, whereas clinical (78%) and farm animal isolates (87%) had a higher prevalence of the esp gene, encoding a surface exposed protein. This study generates knowledge on the genetic diversity of E. faecalis with antibiotic resistance and virulence characteristics from various sources in Malaysia.

Matched MeSH terms: Environmental Microbiology
Fulltext Antimicrobial susceptibility of Leptospira spp. isolated from environmental, human and animal sources in Malaysia

Benacer D, Zain SN, Ooi PT, Thong KL

Indian J Med Microbiol, 2017 Jan-Mar;35(1):124-128.
PMID: 28303833 DOI: 10.4103/ijmm.IJMM_15_458

Leptospirosis is a zoonosis with worldwide distribution caused by pathogenic spirochetes of the genus Leptospira. The aim of this study was to evaluate the susceptibility of isolates obtained from different hosts. A total of 65 Leptospira isolates from humans (n = 1), zoonoses (rat, n = 60; dog, n = 1; swine, n = 1) and environment (n = 2) were tested against six antibiotics. All the isolates were resistant to trimethoprim and sulphamethoxazole and had high MIC toward chloramphenicol (MIC90: 6.25 μg/ml). All except one environment isolate were sensitive to ampicillin, doxycycline and penicillin G.

Matched MeSH terms: Environmental Microbiology*
Isolation, identification and diesel-oil biodegradation capacities of indigenous hydrocarbon-degrading strains of Cellulosimicrobium cellulans and Acinetobacter baumannii from tarball at Terengganu beach, Malaysia

Nkem BM, Halimoon N, Yusoff FM, Johari WLW, Zakaria MP, Medipally SR, et al.

Mar Pollut Bull, 2016 Jun 15;107(1):261-268.
PMID: 27085593 DOI: 10.1016/j.marpolbul.2016.03.060

In this study, we isolated two indigenous hydrocarbon-degrading bacteria from tarball found in Rhu Sepuluh beach, Terengganu, Malaysia. These bacteria were identified based on their physiological characteristic and 16S rRNA gene sequence analysis, and they showed 99% similarity with Cellulosimicrobium cellulans DSM 43879 and Acinetobacter baumannii ATCC 19606 respectively. Their hydrocarbon-degrading capabilities were tested using diesel-oil as sole carbon source. Results analysed using GC-MS, showed diesel-oil alkanes were degraded an average 64.4% by C. cellulans and 58.1% by A. baumannii with medium optical density reaching 0.967 (C. cellulans) and 1.515 (A. baumannii) in minimal salt media at 32°C for 10days. Individual diesel-oil alkanes were degraded between 10%-95.4% by C. cellulans and 0.2%-95.9% by A. baumannii. Both strains utilized diesel-oil for growth. The study suggests both strains are part of indigenous hydrocarbon-degrading bacteria in tarball with potential for bioremediation of oil-polluted marine environment.

Matched MeSH terms: Environmental Microbiology
Fulltext Overview of Molecular Typing Tools for The Characterization of Salmonella enterica in Malaysia

Ngoi ST, Teh CS, Chai LC, Thong KL

Biomed Environ Sci, 2015 Oct;28(10):751-64.
PMID: 26582097 DOI: 10.3967/bes2015.105
Matched MeSH terms: Environmental Microbiology
Fulltext Genome-Wide Transcription Study of Cryptococcus neoformans H99 Clinical Strain versus Environmental Strains

Movahed E, Munusamy K, Tan GM, Looi CY, Tay ST, Wong WF

PLoS One, 2015;10(9):e0137457.
PMID: 26360021 DOI: 10.1371/journal.pone.0137457

The infection of Cryptococcus neoformans is acquired through the inhalation of desiccated yeast cells and basidiospores originated from the environment, particularly from bird's droppings and decaying wood. Three environmental strains of C. neoformans originated from bird droppings (H4, S48B and S68B) and C. neoformans reference clinical strain (H99) were used for intranasal infection in C57BL/6 mice. We showed that the H99 strain demonstrated higher virulence compared to H4, S48B and S68B strains. To examine if gene expression contributed to the different degree of virulence among these strains, a genome-wide microarray study was performed to inspect the transcriptomic profiles of all four strains. Our results revealed that out of 7,419 genes (22,257 probes) examined, 65 genes were significantly up-or down-regulated in H99 versus H4, S48B and S68B strains. The up-regulated genes in H99 strain include Hydroxymethylglutaryl-CoA synthase (MVA1), Mitochondrial matrix factor 1 (MMF1), Bud-site-selection protein 8 (BUD8), High affinity glucose transporter 3 (SNF3) and Rho GTPase-activating protein 2 (RGA2). Pathway annotation using DAVID bioinformatics resource showed that metal ion binding and sugar transmembrane transporter activity pathways were highly expressed in the H99 strain. We suggest that the genes and pathways identified may possibly play crucial roles in the fungal pathogenesis.

Matched MeSH terms: Environmental Microbiology*

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