Bangladesh Journal of Microbiology

Textile Dye Decolorization Potential of Bacillus pumilus and Staphylococcus saprophyticus Isolated From Textile Industry Effluents

2024-05-20T12:59:32+00:00

Textile dyeing industries are usually chastised for being big polluters due to the poisonous nature of most dyes, which endangers all kinds of life, including people. In this study, dye degrading bacteria were isolated from water and soil samples contaminated with textile dye taken from Batik palli in Narayanganj and the ability of five isolated bacteria including Staphylococcus saprophyticus, Bacillus pumilus, Micrococcus endophyticus, Pseudomonas mendocina, and Acinetobacter baumannii, to decolorize crystal violet (CV) dye was investigated. Among these, Bacillus pumilus decolorized 58% of CV at 250 ppm, while Staphylococcus saprophyticus decolorized 48% of CV, after 3 days of incubation at 37°C. We examined multiple temperature and pH conditions to determine the best parameters for CV dye decolorization. Bacillus pumilus boosted decolorization rates by 65.39% at 37°C and at pH 7.0, while Staphylococcus saprophyticus increased decolorization rates by 58.73%, at 37°C and at pH 5.0. Furthermore, extending the incubation period to 6 days enhanced decolorization rate in both isolates, with Bacillus pumilus increased from 58% to 65% and Staphylococcus saprophyticus increased from 48% to 58%. Nevertheless, the inclusion of co-substrates such glucose and yeast extract further boosting decolorization rate for both isolates, approximately tripling it. As a result, this study discovered indigenous bacteria capable of decolorizing CV dye, implying that they could be employed in the treatment of textile wastewater effluents.

Bangladesh J Microbiol, Volume 40, Number 2, December 2023, pp 50-54

Isolation of Potential Azo dye Degrading/Tolerating Bacteria from Polluted Environment

2024-05-28T07:03:43+00:00

Various industries including the food and textile industries result in the release of azo dyes into the environment. These dyes are known to exert toxic effects on humans, animal and plants. Biological methods of azo dye bioremediation is a solution for the detoxification of azo dye in the environment. The present study was undertaken to isolate bacteria with potential for azo dye bioremediation. From five polluted environment samples, eight bacteria were isolated in azo dye supplemented Nutrient agar. Six isolates (75%, n=8) decolorized azo dye completely following 24 hours of incubation. The control tube with no bacterial inoculation remained blue, indicating that only microbial biotransformation processes were taking place. In each case, a blue-colored ring remained at the top, indicating the anoxic nature of the dye decolorization process. All isolates grew in presence of 400 ppm, 60% tolerated 600 ppm and 20% tolerated 800 ppm, whereas 1000ppm was inhibitory for growth of all isolates. Dead autoclaved cells of three representative isolates were tested for biosorption potential. Only one isolate turned the methylene blue supplemented nutrient broth colorless. This explains that this isolate was not metabolizing methylene blue rather it bound the dye to the cell structure. Two isolates did not show biosorption abilities indicating that their mechanism of bioremediation was enzymatic reduction. 16s rDNA sequencing identified two of the isolates as Lysinibacillus capsici and Stenotrophomonas muris.

Bangladesh J Microbiol, Volume 40, Number 2, December 2023, pp 56-59

Biofilm-Producing and Specific Antibiotic Resistance Genes in Pseudomonas aeruginosa Isolated from Patients Admitted to a Tertiary Care Hospital, Bangladesh

2024-06-02T14:12:39+00:00

Pseudomonas aeruginosa is one of the organisms well-known for producing biofilm. Biofilms are responsible for persistent infections and antimicrobial resistance. The aim of this was to investigate P. aeruginosa for its ability to form biofilm. Genes that were responsible for the production of biofilms and biofilm-specific antimicrobial resistance were detected. The association between antibiotic resistance and biofilm was investigated. This cross-sectional study was conducted from July 2017 to December 2018. A total of 446 samples (infected burns, surgical wounds, and ETA) were collected from admitted patients at Dhaka Medical College and Hospital, Bangladesh. P. aeruginosa was isolated and identified by biochemical tests and PCR. Biofilm production by the tissue culture plate (TCP) method was followed by the detection of biofilm[1]producing genes (pqsA, pslA, pslD, pslH, pelA, lasR) and biofilm-specific antibiotic resistance genes (ndvB, PA1874, PA1876, PA1877) by PCR. The antibiotic susceptibility test was carried out by the disc diffusion method; for colistin agar dilution, the MIC method was followed. Among 232 (52.02%) positive strains of P. aeruginosa, 24 (10.30%) produced biofilms in TCPM. Among biofilm-producing genes, pqsA was found the highest number of isolates (79.17%), which was followed by pslA and pelA (70.83%). Other were found in lesser extent. Among the biofilm-specific antibiotic resistance genes, 16.67% of the isolates had ndvB, and 8.33% had PA1874 and PA1877. Biofilm-forming strains were significantly resistant to colistin in comparison to non-biofilm-forming ones. In conclusion, detection of biofilm-forming genes may be a good tool for the evaluation of biofilm production, which will help in prompt and better management of chronic or device-associated infections.

Bangladesh J Microbiol, Volume 40, Number 2, December 2023, pp 60-65

Diversity of Plant Growth Promoters (PGP) Isolated from Agricultural Fields of Bangladesh

2024-06-02T14:43:47+00:00

With an emphasis on leguminous plants like Glycine max (soybean), Clitoria ternatea, and non-leguminous plants like Phaseolus lunatus, this study investigates the diversity of Plant Growth-Promoting Rhizobacteria (PGPR) isolated from the root nodules and rhizospheres of agricultural soil. Seventeen of the 42 isolates were chosen for further analysis. Isolates were screened through phenotypic characterization, presumptive identification, and evaluation of their plant growth-promoting (PGP) qualities. Amplification of the nitrogen[1]fixing nifH gene, the nodulation-inducing nodC gene, and the 16S rRNA were among the molecular investigations carried out. Three examined PGP features were present in 35% of the isolates, according to the results. From pH levels of 4.5 to 9, temperatures of 37oC to 40oC and salt concentrations of 1% or less, the isolates showed versatility in a variety of environmental circumstances. Resistant to high temperatures (40°C), slow-growing rhizobia (22%) were shown to be sensitive to high pH (9). Tilt and Tafgor pesticides had a more severe influence on PGP traits and development than Shadhin G and Semcup. The design and efficacy of biofertilizers, agro-economic progress, and sustainable agriculture are among the topics on which this qualitative study sheds important light.

Bangladesh J Microbiol, Volume 40, Number 2, December 2023, pp 66-74

Antimicrobial and Membrane Stabilization Activity of Plant Extracts Against Pathogenic Bacteria and Fungi

2024-06-02T15:40:00+00:00

The use and search for antimicrobial drugs derived from plants have accelerated in recent years. The present study was aimed to determine the antimicrobial, antibiofilm and membrane stabilization activities of plant extracts. Crude extracts of four plants namely, Mikania scandens (L.), Mimosa pudica (L.), Murraya paniculata (L.), and Syzygium aromaticum (L.) were tested against eleven human pathogens including four biofilm producing bacterial strains Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus, and one fungal strain Candida albicans. The antimicrobial activities as well as minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extracts were evaluated using disc diffusion and macro-broth dilution methods respectively. Among the plant extracts, ethanol extract of S. aromaticum exhibited the largest zone of inhibition 35 mm in diameter against Bacillus subtilis at 500 µg/disc concentrations. The lowest MIC (1000 µg/ml) and MBC (2500 µg/ml) were determined against P. aeruginosa with the same extract of S. aromaticum. In case of time kill assay, S. aromaticum extract showed the lowest optical density (OD₆₀₀) 0.2 against E coli in 3h at MBC concentration. Moreover, the same extract of S. aromaticum displayed the strong antibiofilm activity, inhibiting 100% biofilm formation of E. coli at 2×MIC concentration. Furthermore, in vitro experiment was performed to evaluate membrane stabilization activity of plant extracts and S. aromaticum showed 100% activity in stabilizing cell membranes, preventing hemolysis of red blood cells. Therefore, this study provides valuable insight for designing antimicrobial products to efficiently eliminating human infections, and the plant extracts could be the potential antimicrobial agent.

Bangladesh J Microbiol, Volume 40, Number 2, December 2023, pp 76-85

Detection of Thermoacidophiles from Yellowstone Hot Spring

2024-06-02T16:30:18+00:00

Aerobic methanotrophic bacteria maintain an unrivalled capability of utilizing methane as their sole carbon and energy source and have been retrieved from various environments. Phylogenetically, true aerobic thermoacidophilic methane oxidizers capable of growing below pH 3 have hitherto been associated only with the phylum Verrucomicrobia. In this report, the initial detection of a moderately thermoacidophilic Methylococcus-like Type Ib methanotroph of the class Gammaproteobacteria from an acidic thermal spring (50oC and pH 2.8) in the Yellowstone National Park, USA is presented. The isolate, termed YT-MC, was identified in a methane enrichment (55°C), which may represent a novel strain in the family Methylococcaceae Type Ib. The existence of this bacterium in the enrichments was demonstrated by the detection of pmoA gene, Southern blotting technique, phase-contrast, and electron microscopy. The coccus-typed cells showed tubular membranes instead of intracytoplasmic membrane systems (ICM). The soluble methane monooxygenase (sMMO) was not detected by PCR, indicating that the biotransformation of methane to methanol is oxidized by the particulate methane monooxygenase (pMMO). Moreover, YT-MC performs in a formerly undiscovered active biological methane sink in geothermal acidic environments, magnifying our knowledge of its ecological role in methane cycling, diversity, and coexistence of aerobic methanotrophy. Furthermore, the present study also reports the isolation and identification of an alphaproteobacterial heterotroph (strain YT-AC) and a verrucomicrobial methanotroph (strain YT-VM) from the same environment.

Bangladesh J Microbiol, Volume 40, Number 2, December 2023, pp 86-94