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A simple method to screen for azo-dye-degrading bacteria

Syed MA, Sim HK, Khalid A, Shukor MY

J Environ Biol, 2009 Jan;30(1):89-92.
PMID: 20112868

A stab-culture method was adapted to screen for azo dyes-decolorizing bacteria from soil and water samples. Decolorized azo dye in the lower portion of the solid media indicates the presence of anaerobic azo dyes-decolorizing bacteria, while aerobic decolorizing bacteria decolorizes the surface portion of the solid media. Of twenty soil samples tested, one soil sample shows positive results for the decolourisation of two azo dyes; Biebrich scarlet (BS) and Direct blue 71 (DB) under anaerobic conditions. A gram negative and oxidase negative bacterial isolate was found to be the principal azo dyes degrader The isolate was identified by using the Biolog identification system as Serratia marcescens.

Matched MeSH terms: Bacteria/growth & development
Fulltext Antibacterial activity of Eurycoma longifolia Jack. A Malaysian medicinal plant

Farouk AE, Benafri A

Saudi Med J, 2007 Sep;28(9):1422-4.
PMID: 17768473

Objective: To evaluate methanolic, ethanolic, acetone and aqueous extracts from different parts of Eurycoma longifolia (E. longifolia) (leave, stem, and root) for antibacterial activity against Gram-positive and Gram-negative bacteria and to utilize the leaves and stem parts rather than the root, which is already used for male sexual enhancement in Malaysia.

Methods: The study took place in the Laboratory of Molecular Biology of Biotechnology Engineering Department, Malaysia between January 2005 and June 2006. Methanolic, ethanolic, acetone and aqueous extracts of leaves, stems and roots of E. longifolia were investigated for their antibacterial properties using Agar-well diffusion method.

Results: The alcoholic and acetone extracts of the leaves and stem extracts were active on both Gram-positive and Gram-negative bacteria except against 2 strains of Gram-negative bacteria (Escherichia coli and Salmonella typhi). The root extracts had no antibacterial activity against Gram-positive and Gram-negative bacteria tested. Aqueous leaves extract showed antibacterial activity against Staphylococcus aureus and Serratia marscesens.

Conclusion: The alcoholic and acetone extracts from leaves and stems of E. longifolia contain potent antibacterial agent(s). This plant can serve as a potential source of antibacterial compounds.

Matched MeSH terms: Gram-Negative Bacteria/growth & development; Gram-Positive Bacteria/growth & development
Antibacterial activity of Lactobacillus acidophilus strains isolated from honey marketed in Malaysia against selected multiple antibiotic resistant (MAR) Gram-positive bacteria

Aween MM, Hassan Z, Muhialdin BJ, Eljamel YA, Al-Mabrok AS, Lani MN

J Food Sci, 2012 Jul;77(7):M364-71.
PMID: 22757710 DOI: 10.1111/j.1750-3841.2012.02776.x

A total of 32 lactic acid bacteria (LAB) were isolated from 13 honey samples commercially marketed in Malaysia, 6 strains identified as Lactobacillus acidophilus by API CHL50. The isolates had antibacterial activities against multiple antibiotic resistant's Staphylococcus aureus (25 to 32 mm), Staphylococcus epidermis (14 to 22 mm) and Bacillus subtilis (12 to 19 mm) in the agar overlay method after 24 h incubation at 30 °C. The crude supernatant was heat stable at 90 °C and 121 °C for 1 h. Treatment with proteinase K and RNase II maintained the antimicrobial activity of all the supernatants except sample H006-A and H010-G. All the supernatants showed antimicrobial activities against target bacteria at pH 3 and pH 5 but not at pH 6 within 72 h incubation at 30 °C. S. aureus was not inhibited by sample H006-A isolated from Libyan honey and sample H008-D isolated from Malaysian honey at pH 5, compared to supernatants from other L. acidophilus isolates. The presence of different strains of L. acidophilus in honey obtained from different sources may contribute to the differences in the antimicrobial properties of honey.

Matched MeSH terms: Gram-Positive Bacteria/growth & development*
Antibacterial activity of ovary extract from sea urchin Diadema setosum

Marimuthu K, Gunaselvam P, Aminur Rahman M, Xavier R, Arockiaraj J, Subramanian S, et al.

Eur Rev Med Pharmacol Sci, 2015 May;19(10):1895-9.
PMID: 26044237

Sea urchin gonad is considered as a highly prized delicacy in several countries. It is also rich in valuable bioactive compounds including polyunsaturated fatty acids (PUFAs) and β-carotene. This study was undertaken to examine the antimicrobial properties of the ovary extract from sea urchin Diadema setosum against selected Gram-negative and Gram-positive bacteria.

Matched MeSH terms: Gram-Negative Bacteria/growth & development; Gram-Positive Bacteria/growth & development
Fulltext Antibacterial effects of 18 medicinal plants used by the Khyang tribe in Bangladesh

Hossan MS, Jindal H, Maisha S, Samudi Raju C, Devi Sekaran S, Nissapatorn V, et al.

Pharm Biol, 2018 Dec;56(1):201-208.
PMID: 29529970 DOI: 10.1080/13880209.2018.1446030

CONTEXT: The resistance of bacteria to antibiotics is raising serious concern globally. Asian medicinal plants could improve the current treatment strategies for bacterial infections. The antibacterial properties of medicinal plants used by the Khyang tribe in Bangladesh have not been investigated.
OBJECTIVE: The present study examines the antibacterial properties of 18 medicinal plants used by the Khyang tribe in day-to-day practice against human pathogenic bacteria.
MATERIALS AND METHODS: Leaves, bark, fruits, seeds, roots and rhizomes from collected plants were successively extracted with hexane, ethyl acetate and ethanol. The corresponding 54 extracts were tested against six human pathogenic bacteria by broth microdilution assay. The antibacterial mode of actions of phytoconstituents and their synergistic effect with vancomycin and cefotaxime towards MRSA was determined by time-killing assay and synergistic interaction assay, respectively.
RESULTS AND DISCUSSION: Hexane extract of bark of Cinnamomum cassia (L.) J. Presl. (Lauraceae) inhibited the growth of MRSA, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii with MIC values below 100 µg/mL. From this plant, cinnamaldehyde evoked at 4 × MIC in 1 h an irreversible decrease of MRSA count Log10 (CFU/mL) from 6 to 0, and was synergistic with vancomycin for MRSA with fractional inhibitory concentration index of 0.3.
CONCLUSIONS: Our study provides evidence that the medicinal plants in Bangladesh have high potential to improve the current treatment strategies for bacterial infection.

Matched MeSH terms: Bacteria/growth & development
Antimicrobial Efficacy of Extemporaneously Prepared Herbal Mouthwashes

Dua K, Sheshala R, Al-Waeli HA, Gupta G, Chellappan DK

Recent Pat Drug Deliv Formul, 2015;9(3):257-61.
PMID: 26051152

Natural products like plants and its components have been in use for treatment and cure of diseases all around the globe from ancient times much before the discovery of the current modern drugs. These substances from the nature are well known to contain components which have therapeutic properties and can also behave as precursors for the synthesis of potential drugs. The beneficial results from herbal drugs are well reported where their popularity in usage has increased across the globe. Subsequently developing countries are now recognizing the many positive advantages from their use which has engaged the expansion of R & D from herbal research. The flow on effect from this expansion has increased the awareness to develop new herbal products and the processes, throughout the entire world. Mouth washes and mouth rinses which have plant oils, plant components or extracts have generated particular attention. High prevalence of gingival inflammation and periodontal diseases, suggests majority of the patients practice inadequate plaque control. Of the currently available mouthwashes in the market, Chlorhexidine gluconate (CHX) has been investigated on a larger scale with much detail. CHX is associated with side effects like staining of teeth when used daily as well as the bitter taste of the mouthwash which leads to patient incompliance. The present research encompasses the antibacterial activity of extemporaneously prepared herbal mouthwash using natural herbs and therefore allows for the potential commercialization with in the herbal and pharmaceutical industries. Also, the present research article reviewed details of various existing patents of herbal mouthwashes which shows the trend of existing market and significance of emerging mouthwashes in both pharmaceutical and herbal industries. The antimicrobial activity of prepared mouthwashes was found to be effective against various strains of bacteria. It also suggests that the prepared herbal mouthwashes may provide an alternative to those containing chemical entities, with enhanced antimicrobial properties and better patient compliance.

Matched MeSH terms: Bacteria/growth & development
Fulltext Antimicrobial activities of Bacillus velezensis strains isolated from stingless bee products against methicillin-resistant Staphylococcus aureus

Baharudin MMA, Ngalimat MS, Mohd Shariff F, Balia Yusof ZN, Karim M, Baharum SN, et al.

PLoS One, 2021;16(5):e0251514.
PMID: 33974665 DOI: 10.1371/journal.pone.0251514

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) have reached epidemic proportions globally. Therefore, there is an urgent need for a continuous supply of antibiotics to combat the problem. In this study, bacteria initially identified as species belonging to the Bacillus amyloliquefaciens operational group were re-identified based on the housekeeping gene, gyrB. Cell-free supernatants (CFS) from the strains were used for antimicrobial tests using the agar well diffusion assay against MRSA and various types of pathogenic bacteria. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and physicochemical characteristics of the CFS were determined. Based on gyrB sequence analysis, five strains (PD9, B7, PU1, BP1 and L9) were identified as Bacillus velezensis. The CFS of all B. velezensis strains showed broad inhibitory activities against Gram-negative and -positive as well as MRSA strains. Strain PD9 against MRSA ATCC 33742 was chosen for further analysis as it showed the biggest zone of inhibition (21.0 ± 0.4 mm). The MIC and MBC values obtained were 125 μl/ml. The crude antimicrobial extract showed bactericidal activity and was stable at various temperatures (40-80°C), pH (4-12), surfactants (Tween 20, Tween 80, SDS and Triton X-100) and metal ions (MgCI2, NaCI2, ZnNO3 and CuSO4) when tested. However, the crude extract was not stable when treated with proteinase K. All these properties resembled the characteristics of peptides. The antimicrobial compound from the selected strain was purified by using solvent extraction method and silica gel column chromatography. The purified compound was subjected to High Performance Liquid Chromatography which resulted in a single peak of the anti-MRSA compound being detected. The molecular weight of the anti-MRSA compound was determined by using SDS-PAGE and zymogram. The size of the purified antimicrobial peptide was approximately ~ 5 kDa. The antimicrobial peptide produced from B. velezensis strain PD9 is a promising alternative to combat the spread of MRSA infections in the future.

Matched MeSH terms: Gram-Negative Bacteria/growth & development; Gram-Positive Bacteria/growth & development
Antimicrobial activities of Psophocarpus tetragonolobus (L.) DC extracts

Sasidharan S, Zuraini Z, Yoga Latha L, Sangetha S, Suryani S

Foodborne Pathog Dis, 2008 Jun;5(3):303-9.
PMID: 18767977 DOI: 10.1089/fpd.2007.0078

Consecutive chloroform, ethanol, and ethyl acetate partitions of extracts from winged bean [Psophocarpus tetragonolobus (L.) DC] root, stem, leaf, and pod extracts were tested for their antimicrobial activity against 19 microbial species, including 11 bacterial pathogens, four yeasts, and four molds using the disk diffusion assay technique. The pod extract was found to be most effective against all of the tested organisms, followed by the stem, root, and leaf extracts, and the ethanol fraction showed the most significant (p < 0.05) antimicrobial activity against all of the tests among three soluble fractions of extract, followed by the ethyl acetate and chloroform fractions. The minimum inhibitory concentrations (MICs) of extracts determined by the broth dilution method ranged from 1.25 to 10.0 mg/mL. The MIC of ethanol fraction of pod extracts was the lowest by comparison with the other two extracts. The MIC for fungi was at or below 2.5 mg/mL and for bacteria was at or above 2.5 mg/mL.

Matched MeSH terms: Bacteria/growth & development
Fulltext Antimicrobial and antioxidant activities of new metal complexes derived from 3-aminocoumarin

Kadhum AA, Mohamad AB, Al-Amiery AA, Takriff MS

Molecules, 2011 Aug 15;16(8):6969-84.
PMID: 21844844 DOI: 10.3390/molecules16086969

3-Aminocoumarin (L) has been synthesized and used as a ligand for the formation of Cr(III), Ni(II), and Cu(II) complexes. The chemical structures were characterized using different spectroscopic methods. The elemental analyses revealed that the complexes where M=Ni(II) and Cu(II) have the general formulae [ML(2)Cl(2)], while the Cr(III) complex has the formula [CrL(2)Cl(2)]Cl. The molar conductance data reveal that all the metal chelates, except the Cr(III) one, are non-electrolytes. From the magnetic and UV-Visible spectra, it is found that these complexes have octahedral structures. The stability for the prepared complexes was studied theoretically using Density Function Theory. The total energy for the complexes was calculated and it was shown that the copper complex is the most stable one. Complexes were tested against selected types of microbial organisms and showed significant activities. The free radical scavenging activity of metal complexes have been determined by measuring their interaction with the stable free radical DPPH and all the compounds have shown encouraging antioxidant activities.

Matched MeSH terms: Bacteria/growth & development
Bacterial dynamics associated with algal antibacterial substances during post harvest desiccation process of Sargassum stolonifolium Phang et Yoshida

Vairappan CS

Indian J Exp Biol, 2003 Aug;41(8):837-45.
PMID: 15248481

Brown algae of genus Sargassum are known to produce relatively higher amount of alginic acid. Optimal extraction of this algalcolloid for local consumption requires in-depth studies on post-harvest treatment of the algal fronds. Present investigation endeavors to establish the dynamics and inter-relationship of moisture content and bacteria found on the surface of the alga and alginic acid content during post-harvest desiccation of Sargassum stolonifolium Phang et Yoshida. Harvested fronds were subjected to desiccation for 31 days and bacterial dynamics were monitored with relation to moisture content and water activity index (a(w)). There was 85% decrease in moisture content, however, a(w) showed a more gradual decrease. Total bacterial count increased during the first week and attained maximal value on day 7. Thereafter, a drastic decrease was seen until day 14, followed by a gradual decline. Six species of bacteria were isolated and identified, i.e. Azomonas punctata, Azomonas sp., Escherichia coli, Micrococcus sp., Proteus vulgaris and Vibrio alginolyticus. Calculated ratios for increase in alginic acid content and decrease in moisture content were almost the same throughout the desiccation process, implying that extracellular alginase-producing bacteria did not use the alginic acid produced by the algae as its carbon source. It became apparent that drastic decrease in bacterial count after day 7 could not be attributed to salinity, moisture content, a(w) or lack of carbon source for the bacteria. The possible exposure of these bacteria to algal cell sap which is formed due to the rupture of algal cells was seen as the most likely reason for the drop in bacterial population. Scanning electron microscope (SEM) micrograph taken on day 10 of desiccation showed the presence of cracks and localities where bacteria were exposed to algal cell sap. In vitro antibacterial tests were carried out to verify the effect of algal extracts. Separation and purification of crude algal extracts via bioassay guided separation methodology revealed the identity of active compounds (i.e. gylcolipids and free fatty acids) involved in this inherently available antibacterial defense mechanism during algal desiccation.

Matched MeSH terms: Gram-Negative Bacteria/growth & development; Gram-Positive Bacteria/growth & development
Fulltext Berberine nanoparticles with enhanced in vitro bioavailability: characterization and antimicrobial activity

Sahibzada MUK, Sadiq A, Faidah HS, Khurram M, Amin MU, Haseeb A, et al.

Drug Des Devel Ther, 2018;12:303-312.
PMID: 29491706 DOI: 10.2147/DDDT.S156123

BACKGROUND: Berberine is an isoquinoline alkaloid widely used in Ayurveda and traditional Chinese medicine to treat illnesses such as hypertension and inflammatory conditions, and as an anticancer and hepato-protective agent. Berberine has low oral bioavailability due to poor aqueous solubility and insufficient dissolution rate, which can reduce the efficacy of drugs taken orally. In this study, evaporative precipitation of nanosuspension (EPN) and anti-solvent precipitation with a syringe pump (APSP) were used to address the problems of solubility, dissolution rate and bioavailability of berberine.
METHODS: Semi-crystalline nanoparticles (NPs) of 90-110 nm diameter for APSP and 65-75 nm diameter for EPN were prepared and then characterized using differential scanning calorimetry (DSC) and X-ray powder diffractometry (XRD). Thereafter, drug content solubility and dissolution studies were undertaken. Berberine and its NPs were evaluated for their antibacterial activity.
RESULTS: The results indicate that the NPs have significantly increased solubility and dissolution rate due to conversion of the crystalline structure to a semi-crystalline form.
CONCLUSION: Berberine NPs produced by both APSP and EPN methods have shown promising activities against Gram-positive and Gram-negative bacteria, and yeasts, with NPs prepared through the EPN method showing superior results compared to those made with the APSP method and the unprocessed drug.

Matched MeSH terms: Bacteria/growth & development
Fulltext Bioactive compounds and biological activities of Jatropha curcas L. kernel meal extract

Oskoueian E, Abdullah N, Ahmad S, Saad WZ, Omar AR, Ho YW

Int J Mol Sci, 2011;12(9):5955-70.
PMID: 22016638 DOI: 10.3390/ijms12095955

Defatted Jatropha curcas L. (J. curcas) seed kernels contained a high percentage of crude protein (61.8%) and relatively little acid detergent fiber (4.8%) and neutral detergent fiber (9.7%). Spectrophotometric analysis of the methanolic extract showed the presence of phenolics, flavonoids and saponins with values of 3.9, 0.4 and 19.0 mg/g DM, respectively. High performance liquid chromatography (HPLC) analyses showed the presence of gallic acid and pyrogallol (phenolics), rutin and myricetin (flavonoids) and daidzein (isoflavonoid). The amount of phorbol esters in the methanolic extract estimated by HPLC was 3.0 ± 0.1 mg/g DM. Other metabolites detected by GC-MS include: 2-(hydroxymethyl)-2 nitro-1,3-propanediol, β-sitosterol, 2-furancarboxaldehyde, 5-(hydroxymethy) and acetic acid in the methanolic extract; 2-furancarboxaldehyde, 5-(hydroxymethy), acetic acid and furfural (2-furancarboxaldehyde) in the hot water extract. Methanolic and hot water extracts of kernel meal showed antimicrobial activity against both Gram positive and Gram negative pathogenic bacteria (inhibition range: 0-1.63 cm) at the concentrations of 1 and 1.5 mg/disc. Methanolic extract exhibited antioxidant activities that are higher than hot water extract and comparable to β-carotene. The extracts tended to scavenge the free radicals in the reduction of ferric ion (Fe(3+)) to ferrous ion (Fe(2+)). Cytotoxicity assay results indicated the potential of methanolic extract as a source of anticancer therapeutic agents toward breast cancer cells.

Matched MeSH terms: Gram-Negative Bacteria/growth & development; Gram-Positive Bacteria/growth & development
Fulltext Characterization and safety evaluation of partially purified bacteriocin produced by Escherichia coli E isolated from fermented pineapple Ananas comosus (L.) Merr

Le VT, Leelakriangsak M, Lee SW, Panphon S, Utispan K, Koontongkaew S

Braz J Microbiol, 2019 Jan;50(1):33-42.
PMID: 30637641 DOI: 10.1007/s42770-018-0014-5

Antibacterial activity of cell-free supernatant from Escherichia coli E against selected pathogenic bacteria in food and aquaculture was the highest against Edwardsiella tarda 3, a significant aquaculture pathogen. Biochemical properties of the bacteriocins were studied and bacteriocin was found to be sensitive to proteinase K, demonstrating its proteinaceous nature. In addition, pH and temperature affected bacteriocin activity and stability. The bacteriocins were partially purified by ammonium sulfate precipitation. The antibacterial activity was only detected in 20% ammonium sulfate fraction and direct detection of its activity was performed by overlaying on the indicator strains. The inhibition zone associated with the antibacterial activity was detected in the sample overlaid by E. tarda 3 and Staphylococcus aureus DMST8840 with the relative molecular mass of about 27 kDa and 10 kDa, respectively. Bacteriocin showed no cytotoxic effect on NIH-3T3 cell line; however, two virulence genes, aer and sfa, were detected in the genome of E. coli E by PCR. The characteristics of bacteriocins produced by E. coli E exhibited the antibacterial activity against both Gram-positive and Gram-negative pathogenic bacteria and the safe use determined by cytotoxicity test which may have interesting biotechnological applications.

Matched MeSH terms: Gram-Negative Bacteria/growth & development; Gram-Positive Bacteria/growth & development
Characterization of anticancer, antimicrobial, antioxidant properties and chemical compositions of Peperomia pellucida leaf extract

Wei LS, Wee W, Siong JY, Syamsumir DF

Acta Med Iran, 2011;49(10):670-4.
PMID: 22071643

Peperomia pellucida leaf extract was characterized for its anticancer, antimicrobial, antioxidant activities, and chemical compositions. Anticancer activity of P. pellucida leaf extract was determined through Colorimetric MTT (tetrazolium) assay against human breast adenocarcinoma (MCF-7) cell line and the antimicrobial property of the plant extract was revealed by using two-fold broth micro-dilution method against 10 bacterial isolates. Antioxidant activity of the plant extract was then characterized using α, α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging method and the chemical compositions were screened and identified using gas chromatography-mass spectrometry (GC-MS). The results of present study indicated that P. pellucida leaf extract possessed anticancer activities with half maximal inhibitory concentration (IC(50)) of 10.4 ± 0.06 µg/ml. The minimum inhibitory concentration (MIC) values were ranged from 31.25 to 125 mg/l in which the plant extract was found to inhibit the growth of Edwardsiella tarda, Escherichia coli, Flavobacterium sp., Pseudomonas aeruginosa and Vibrio cholerae at 31.25 mg/l; Klebsiella sp., Aeromonas hydrophila and Vibrio alginolyticus at 62.5 mg/l; and it was able to control the growth of Salmonella sp. and Vibrio parahaemolyticus at 125 mg/l. At the concentration of 0.625 ppt, the plant extract was found to inhibit 30% of DPPH, free radical. Phytol (37.88%) was the major compound in the plant extract followed by 2-Naphthalenol, decahydro- (26.20%), Hexadecanoic acid, methyl ester (18.31%) and 9,12-Octadecadienoic acid (Z,Z)-, methyl ester (17.61%). Findings from this study indicated that methanol extract of P. pellucida leaf possessed vast potential as medicinal drug especially in breast cancer treatment.

Matched MeSH terms: Bacteria/growth & development
Characterization of pyrene and chrysene degradation by halophilic Hortaea sp. B15

Al Farraj DA, Hadibarata T, Yuniarto A, Syafiuddin A, Surtikanti HK, Elshikh MS, et al.

Bioprocess Biosyst Eng, 2019 Jun;42(6):963-969.
PMID: 30888502 DOI: 10.1007/s00449-019-02096-8

Polycyclic aromatics hydrocarbons (PAHs) are ubiquitous and toxic pollutants that are dangerous to humans and living organism in aquatic environment. Normally, PAHs has lower molecular weight such as phenanthrene and naphthalene that are easy and efficient to degrade, but high-molecular-weight PAHs such as chrysene and pyrene are difficult to be biodegraded by common microorganism. This study investigated the isolation and characterization of a potential halophilic bacterium capable of utilizing two high-molecular-weight PAHs. At the end of the experiment (25-30 days of incubation), bacterial counts have reached a maximum level (over 40 × 1016 CFU/mL). The highest biodegradation rate of 77% of chrysene in 20 days and 92% of pyrene in 25 days was obtained at pH 7, temperature 25 °C, agitation of 150 rpm and Tween 80 surfactant showing to be the most impressive parameters for HMWPAHs biodegradation in this research. The metabolism of initial compounds revealed that Hortaea sp. B15 utilized pyrene to form phthalic acid while chrysene was metabolized to form 1-hydroxy-2-naphthoic acid. The result showed that Hortaea sp. B15 can be promoted for the study of in situ biodegradation of high molecular weight PAH.

Matched MeSH terms: Bacteria/growth & development*
Fulltext Chemical composition and antibacterial and cytotoxic activities of Allium hirtifolium Boiss

Ismail S, Jalilian FA, Talebpour AH, Zargar M, Shameli K, Sekawi Z, et al.

Biomed Res Int, 2013;2013:696835.
PMID: 23484141 DOI: 10.1155/2013/696835

Allium hirtifolium Boiss. known as Persian shallot, is a spice used as a traditional medicine in Iran and, Mediterranean region. In this study, the chemical composition of the hydromethanolic extract of this plant was analyzed using GC/MS. The result showed that 9-hexadecenoic acid, 11,14-eicosadienoic acid, and n-hexadecanoic acid are the main constituents. The antibacterial activity of the shallot extract was also examined by disk diffusion and microdilution broth assays. It was demonstrated that Persian shallot hydromethanolic extract was effective against 10 different species of pathogenic bacteria including methicillin resistant Staphylococcus aureus (MRSA), methicillin sensitive Staphylococcus aureus (MSSA), Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Escherichia coli, Escherichia coli O157:H7, Salmonella typhimurium, Proteus mirabilis, and Klebsiella pneumoniae. Specifically, the minimum concentration of the extract which inhibited bacterial growth (MIC values) was 1.88 mg/mL for most of the gram-positive bacteria. This concentration was not much different from the concentration that was safe for mammalian cells (1.50 mg/mL) suggesting that the hydromethanolic extract of Persian shallot may be a safe and strong antibacterial agent.

Matched MeSH terms: Bacteria/growth & development*
Coexisting mechanisms of bacterial community are changeable even under similar stable conditions in a chemostat culture

Abdul Aziz FA, Suzuki K, Honjo M, Amano K, Mohd Din ARJB, Tashiro Y, et al.

J Biosci Bioeng, 2021 Jan;131(1):77-83.
PMID: 33268319 DOI: 10.1016/j.jbiosc.2020.09.009

The coexisting mechanism of a synthetic bacterial community (SBC) was investigated to better understand how to manage microbial communities. The SBC was constructed with three kinds of phenol-utilizing bacteria, Pseudomonas sp. LAB-08, Comamonas testosteroni R2, and Cupriavidus sp. P-10, under chemostat conditions supplied with phenol as a sole carbon and energy source. Population densities of all strains were monitored by real-time quantitative PCR (qPCR) targeting the gene encoding the large subunit of phenol hydroxylase. Although the supply of phenol was stopped to allow perturbation in the SBC, all of the strains coexisted and the degradation of phenol was maintained for more than 800 days. The qPCR analyses showed that strains LAB-08 and R2 became dominant simultaneously, whereas strain P-10 was a minor population. This phenomenon was observed before and after the phenol-supply stoppage. The kinetic parameters for phenol of the SBC changed before and after the phenol-supply stoppage, which suggests a change in functional roles of strains in the SBC. Transcriptional levels of phenol hydroxylase and catechol dioxygenases of three strains were monitored by reverse-transcription qPCR (RT-qPCR). The RT-qPCR analyses revealed that all strains shared phenol and survived independently before the phenol-supply stoppage. After the stoppage, strain P-10 would incur the cost for degradation of phenol and catechol, whereas strains LAB-08 and R2 seemed to be cheaters using metabolites, indicating the development of the metabolic network. These results indicated that it is important for the management and redesign of microbial communities to understand the metabolism of bacterial communities.

Matched MeSH terms: Bacteria/growth & development
Corrosion and bioactivity performance of graphene oxide coating on TiNb shape memory alloys in simulated body fluid

Saud SN, Hosseinian S R, Bakhsheshi-Rad HR, Yaghoubidoust F, Iqbal N, Hamzah E, et al.

Mater Sci Eng C Mater Biol Appl, 2016 Nov 01;68:687-694.
PMID: 27524069 DOI: 10.1016/j.msec.2016.06.048

In the present work, the microstructure, corrosion, and bioactivity of graphene oxide (GO) coating on the laser-modified and -unmodified surfaces of TiNb shape memory alloys (SMAs) were investigated. The surface morphology and chemical composition was examined using field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The surface modification was carried out via a femtosecond laser with the aim to increase the surface roughness, and thus increase the adhesion property. FE-SEM analysis of the laser-treated Ti-30at.% Nb revealed the increase in surface roughness and oxygen/nitrogen containing groups on the Ti-30at.% Nb surface after being surface modified via a femtosecond laser. Furthermore, the thickness of GO was increased from 35μm to 45μm after the surface was modified. Potentiodynamic polarisation and electrochemical impedance spectroscopy studies revealed that both the GO and laser/GO-coated samples exhibited higher corrosion resistance than that of the uncoated TiNb SMA sample. However, the laser/GO-coated sample presented the highest corrosion resistance in SBF at 37°C. In addition, during soaking in the simulated body fluid (SBF), both the GO and laser/GO coating improved the formation of apatite layer. Based on the bioactivity results, the GO coating exhibited a remarkable antibacterial activity against gram-negative bacteria compared with the uncoated. In conclusion, the present results indicate that Ti-30at.% Nb SMAs may be promising alternatives to NiTi for certain biomedical applications.

Matched MeSH terms: Gram-Negative Bacteria/growth & development
Culturable bacteria in adults of a Southeast Asian black fly, Simulium tani (Diptera:Simuliidae)

Lee HY, Loong SK, Ya'cob Z, Low VL, Teoh BT, Ahmad-Nasrah SN, et al.

Acta Trop, 2021 Jul;219:105923.
PMID: 33878305 DOI: 10.1016/j.actatropica.2021.105923

Although the microbiome of blood-feeding insects serves an integral role in host physiology, both beneficial and pathogenic, little is known of the microbial community of black flies. An investigation, therefore, was undertaken to identify culturable bacteria from one of Malaysia's most common black flies, Simulium tani Takaoka and Davies, using 16S rDNA sequencing, and then evaluate the isolates for antibiotic resistance and virulence genes. A total of 20 isolates representing 11 bacterial species in four genera were found. Five isolates showed β-hemolysis on Columbia agar, and virulence genes were found in three of these isolates. Some degree of resistance to six of the 12 tested antibiotics was found among the isolates. The baseline data from this study suggest rich opportunities for comparative studies exploring the diversity and roles of the microbiome of S. tani and other Southeast Asian black flies.

Matched MeSH terms: Bacteria/growth & development*
Fulltext Culture Medium Development for Microbial-Derived Surfactants Production-An Overview

Nurfarahin AH, Mohamed MS, Phang LY

Molecules, 2018 May 01;23(5).
PMID: 29723959 DOI: 10.3390/molecules23051049

Surfactants are compounds that can reduce the surface tension between two different phases or the interfacial tension of the liquid between water and oil, possessing both hydrophilic and hydrophobic moieties. Biosurfactants have traits that have proven to be advantageous over synthetic surfactants, but these compounds do not compete economically with synthetic surfactants. Different alternatives increase the yield of biosurfactants; development of an economical production process and the usage of cheaper substrates during process have been employed. One of the solutions relies on the suitable formulation of a production medium by including alternative raw materials sourced from agro-wastes, hydrocarbons, or by-products of a process might help in boosting the biosurfactant production. Since the nutritional factors required will be different among microorganisms, the establishment of a suitable formulation for biosurfactant production will be challenging. The present review describes various nutrients and elements considered in the formulation of a production medium with an approach focusing on the macronutrient (carbon, nitrogen source, and C/N ratio), minerals, vitamins, metabolic regulators, and salinity levels which may aid in the study of biosurfactant production in the future.

Matched MeSH terms: Bacteria/growth & development*

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