Bangladesh Journal of Microbiology <p>The official journal of the Bangladesh Society of Microbiologists. Full text articles available</p> Bangladesh Society of Microbiologists en-US Bangladesh Journal of Microbiology 1011-9981 Isolation and Characterization of Antimicrobial Compound from Stem Bark of Traditional Medicinal Plant Sonneratia apetala: Evaluation of their antimicrobial, Cytotoxic and Antioxidant Properties <p>Sonneratia apetala (S. apetala) (Lythraceae) has been investigated for the isolation and characterization of antimicrobial compounds and evaluation of their biological activities. The chloroform extract of the stem bark and different partitionate of the chloroform extracts i.e. Petroleum ether soluble fraction (PESF), Ethyl acetate soluble fraction(EASF), Methanol soluble fraction(MSF) and aqueous soluble fractions (ASF) were subjected to different chromatographic techniques to isolate secondary metabolites. Successive chromatographic separation and purification yielded a total of two compounds identified and characterized as Taraxerone(1) and 5,8-dihydroxy- 6-methoxy-4,9-dioxo-1,3,4,9-tetrahydronaphthol[2,3-c]furan-1-yl acetate (2) by extensive proton NMR spectrum (1H-NMRspectrum) analysis. The different partitionate like PESF, EASF, MESF and ASF were subjected to screen their antimicrobial properties against some selected Gram positive and Gram negative bacteria and fungi, brine shrimp lethality and antioxidant activities. The maximum zone of inhibition of chloroform extract was found against Pseudomonas sp. (16mm). All fractions showed more activity against Gram negative bacteria then Gram positive bacteria. In the brine shrimp lethality bioassay, among all extracts, the petroleum ether and ethyl acetate soluble fraction showed significant lethality having the LC<sub>50</sub> value of 7.72 μg/ml. The antioxidant activity was evaluated in terms of determination of free radical scavenging activity (DPPH assay). Among all the extracts of S. apetala the highest free radical scavenging activity showed by (Methanol soluble fraction) MESF with IC<sub>50</sub> value 18.0 μg/ml.</p> <p>Bangladesh J Microbiol, Volume 38, Number 1, June 2021, pp 1-5</p> Md Arifur Rahman Ahmed Abu Rus’d Md Enamul Haque Copyright (c) 2021 Bangladesh Journal of Microbiology 2021-09-14 2021-09-14 38 1 1 5 10.3329/bjm.v38i1.55529 Antibacterial and Antibiofilm Activities of Nigella sativa L. Seed Extracts <p>The emergence of antibiotic-resistant bacteria is a major public health problem. Consequently, the development of new antimicrobials that act on novel bacterial targets and are less susceptible to resistance are of primary importance to researchers in academia and industry alike. The present study was aimed to determine the antimicrobial and antibiofilm activities of Nigella sativa seed extracts. For this, primary (qualitative) and quantitative antibacterial activities of Nigella sativa seed extracts were determined against ten human pathogenic bacteria including four biofilm producing bacterial strains Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus. The antibacterial 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. The seed extracts of N. sativa exhibited the highest extract yields (w/v) 23.3% and 21.35% with ethanol and petroleum ether, respectively. The crude extract (essential oil) of petroleum ether exhibited superior antibacterial activity (36 mm in diameter zone of inhibition) against biofilm forming E. coli on a disc diffusion assay at a concentration of 1000 μg/disc when compared to that of ethanolic crude extract. Moreover, the lowest MIC and MBC values were determined as 500 μg/ml and 1500 μg/ml respectively with the same petroleum ether extract against E. coli. However, N. sativa essential oil obtained from petroleum ether extract of seed inhibited 94% biofilm formation of E. coli at 2×MIC concentration. Moreover, at the same concentration (2×MIC), the ethanol extract inhibited 56% biofilm formation of P. aeruginosa. These results consistently revealed that it is possible to isolate novel antimicrobial agents capable of completely eradicating microbial infections including antibiotic resistance. Therefore, bioactive natural products present in plant resources would represent a noteworthy alternative to commercial antibiotics helping treatment of human antibiotic resistant infections.</p> <p>Bangladesh J Microbiol, Volume 38, Number 1, June 2021, pp 7-13</p> Md Shafiqur Rahman Tithi Roy Copyright (c) 2021 Bangladesh Journal of Microbiology 2021-09-14 2021-09-14 38 1 7 13 10.3329/bjm.v38i1.55530 Antibacterial activity of ethanol extracts of betel leaf (Piper betle L.) and areca (Areca catechu L.) nuts against food borne and oral pathogens <p>Antimicrobial activity of ethanol extracts of betel leaf (Piper betle L.) and areca nut (Areca catechu) against six food borne enteric pathogens viz. Staphylococcus aureus (ATCC 25923), Staphylococcus epidermidis (icddr,b), Salmonella typhimurium (AIM-40, icddr,b), Escherichia coli (ATCC 25922), Escherichia coli O157:H7 (ATCC 12079) and Bacillus cereus (ATCC 12079), and four oral pathogens such as isolates 1 &amp; 2 of each of the two bacteria viz. Staphylococcus sp. and Pseudomonas sp. was investigated. Ethanol extract of betel leaf produced highest zone of inhibition (18.0 ± 1.91 mm) against Staphylococcus epidermidis (icddr,b) whereas that of areca nut produced highest zone of inhibition (15.0 ± 0.816 mm) against Staphylococcus aureus (ATCC 25923). But no inhibition was found against Salmonella typhimurium (ATCC AIM-40, icddr,b), Escherichia coli (ATCC 25922), and Escherichia coli O157:H7 (ATCC 12079) by the Ethanol extract of betel leaf. The MIC and MBC values of both ethanol extracts indicated that Gram positive organisms were more susceptible than Gram negative organisms. Highest antimicrobial activity of ethanol extracts of betel leaf was found against the isolate 1 of Staphylococcus sp. (16.5±0.5) and that of areca nut was recorded against the isolate 1 of Staphylococcus sp. (12.0±0.5) and the isolate 2 of Pseudomonas sp. (12.0±0.5). Present study reveals the potentials of both the extracts to inhibit food borne enteric and oral pathogens that could be used as food preservatives to prevent the food borne illness as well as for maintaining the oral and gut health.</p> <p>Bangladesh J Microbiol, Volume 38, Number 1, June 2021, pp 15-19</p> Masuda Khatun Md Mahfuzul Hoque Copyright (c) 2021 Bangladesh Journal of Microbiology 2021-09-14 2021-09-14 38 1 15 19 10.3329/bjm.v38i1.55531 Antibiotic Sensitivity and Virulence Genes in Staphylococcus aureus Isolates from Surgical Site Infection <p>Fourteen multi drug resistant Staphylococcus aureus isolates from surgical site infection were analyzed for their antibiotic sensitivity and the presence of nine virulence genes. The isolates showed a high resistance pattern, all being resistant to methicillin, oxacillin, azithromycin, ceftazidime and amoxyclav. Seven of the isolates were sensitive to linezolid; three were sensitive to trimethoprim: sulfamethoxazol and another three were sensitive to ciprofloxacin. Ceftriaxone, gentamicin and amikacin were the drugs of choice as nine (64.3%) isolates were sensitive to ceftriaxone, eleven (78.6%) were sensitive to gentamicin and another eleven (78.6%) to amikacin. The present study focused to identify nine important virulence genes including intrinsic methicillin resistance gene mecA, methicillin resistance assisting gene femA, toxic shock syndrome toxin gene tst, exfoliative toxin A and B genes, eta and etb, Panton Valentine leukocidin gene LukS/F-PVL, along with three enterotoxin genes sec, sed and see. According to the presence of mecA gene and antibiotic resistance profile, two isolates were identified as methicillin resistant Staphylococcus aureus. However, another isolate, despite harbouring both mecA and femA genes, was sensitive to ceftriaxone which excluded it from being considered as an MRSA. Thus, the ratio of MRSA can be considered to be quite high (2/14) among the strains. Interestingly, most of the isolates (10/14) harboured femA gene, the majority of which were mecA negative with an MSSA type antibiotic profile. Although considered as a marker for community acquired MRSA, LukS/F-PV was found in half of these nosocomial isolates. Five, four and two of the isolates harboured etb, tst and sec gene, respectively. However, all the isolates were negative for eta, sed and see genes. Two isolates showed the co-existance of “femA, LukS/F-PV, etb, and tst” genes. Another two virulence gene patterns observed were “femA, mecA, tst, sec” and “femA, LukS/F-PV, etb”. The presence of several virulence genes can be correlated to the highly pathogenic nature of the isolates.</p> <p>Bangladesh J Microbiol, Volume 38, Number 1, June 2021, pp 21-26</p> Marufa Zerin Akhter Nuheen Akter Sunjukta Ahsan Fatema Moni Chowdhury Copyright (c) 2021 Bangladesh Journal of Microbiology 2021-09-14 2021-09-14 38 1 21 26 10.3329/bjm.v38i1.55532 Chromium bioremediation potential of indigenous Bacillus pumillus isolated from river water of Bangladesh <p>Bangladesh has achieved rapid industrialization in recent years. However, many of these industries lack proper effluent treatment plant and discharge untreated effluent laden with different heavy metals into the major rives that surround these industries, affecting the environment as well as human and animal health. Aiming to develop a sustainable effluent treatment plant, a heavy metal tolerant Bacillus pumillus isolated from polluted river water of Bangladesh was studied for its chromium bioremediation potential. Reduction of hexavalent chromium using the Sdiphenylcarbazide (DPC) method showed that whole cells of the Bacillus pumillus reduced 89.5%, 75%, 73% and 45% of 1.0, 2.5, 5 and 10mg/L Cr(VI) to Cr(III), respectively. This bacterium reduced 100% of 20mg/L Cr(VI) to Cr(III) within 8 hours, in a growth associated pattern. A 20kb plasmid was detected in this Bacillus pumillus, and loss of this plasmid did not cause complete impairment of chromium tolerance capacity, though the tolerance efficiency was reduced. The Bacillus pumillus studied in the current study therefore shows its potential to develop a sustainable chromium bioremediation method.</p> <p>Bangladesh J Microbiol, Volume 38, Number 1, June 2021, pp 27-30</p> Sangita Ahmed Rakibul Hasan Sumaiya Aziz Khan Razu Ahmed Copyright (c) 2021 Bangladesh Journal of Microbiology 2021-09-14 2021-09-14 38 1 27 30 10.3329/bjm.v38i1.55533