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In leather industries and tanneries, large amount of wastes has been disposed; which polluting water, soil, and atmosphere and causing serious human health problems. In particular, chemical dehairing process of leather industries produces fair amount of toxic wastes. It is, thus, urgently needed to use alternative processes free from pollution. As more than 90% of keratin is contained in feather, it is desirable to develop bioremediation process using keratinolytic microorganisms. In the present investigation, therefore, we first identified Bacillus cereus and Pseudomonas sp. to be able to produce keratinase. Then, the optimization was performed to maximize the keratinase activity with respect to cultivation temperature, pH, and incubation time. Moreover, the effects of metal ions and various substrates on keratinase activity were also investigated. The result indicates that keratinase activity became maximum at 50°C for both strains, whereas the optimal pH was 10.0 for B. cereus and 7.0 for Pseudomonas sp. The highest keratinase activity of 74.66 ± 1.52 U/mL was attained by B. cereus, whereas 57.66 ± 2.52 U/mL was attained by Pseudomonas sp. Enzymatic dehairing efficiency of leathers was also compared with chemical dehairing (Na2S and CaO), where complete dehairing was achieved by treating them with crude keratinase. Partial enzyme purification was performed by acetone precipitation. Batch cultivation of B. cereus using 1 L fermentor indicates a potential candidate for large-scale keratinase production. Thus, keratinase enzyme by degrading poultry wastes (feather) can be an alternative approach to chemical dehairing in leather industries, thus preventing environmental pollution through bioremediation.

Background and Aims Use of technological gadgets has rapidly been increasing among adolescents, which may result in health issues and technology addiction. This study focuses on the prevalence of usage of technological gadgets and health‐related complications among secondary school‐going children of Bangladesh. Methods A total of 1803 secondary school students from 21 different districts of Bangladesh participated in the study. The children were asked questions relating to their access to electronic gadgets, time spent on outdoor activities, and whether they experienced any health‐complications as an after‐effect of the usage. A binary logistic regression model was adapted considering time spent on gadgets as an independent variable and health problems (physical and mental) as the dependent variable. Results Among all the gadgets, 67.11% of the participants were reported to use mobile phones on a daily basis. Due to the ongoing COVID‐19 pandemic, 24.48% of respondents used electronic gadgets for attending online classes. The participants were reported to use gadgets significantly more ( P < .05) in 2020 as compared to 2019. Children showed less tendency to spend time in outdoor activities. More than 50% of the participants spend time doing outdoor activities for less than 1 hour daily. An association between gadget use and health problems like headache, backache, visual disturbance, and sleeping disturbance has been observed in our study. Conclusion This study demonstrates that different socio‐demographic factors have influence on the use of gadgets by children, and this use has greatly been affecting both the physical and mental health of the secondary school‐going students of Bangladesh.

Chittagong is the second most populated city in Bangladesh where drinking water is supplied using small jar. Water quality is an important concern for the consumers and, therefore, the present study was done by collecting 38 drinking jar water samples from Chittagong City, Bangladesh to determine the microbial contamination and physiochemical properties. Molecular study was done by the PCR amplification of 16SrDNA, LacZ and uidA gene for the identification of bacteria, coliform and fecal coliform. TVC, MPN and different biochemical test were done for enumeration and identification. TDS, pH, and metals (Fe, As, Pb and Cr) concentration were also measured. No heavy metal (As, Pb and Cr) was found in any of the water samples but Fe was detected in low concentrations (0.02-0.05 mg/l). TDS and pH level were normal in all samples. But microbial contaminations were (60.53 and 50%) recorded in molecular and biochemical test, respectively. The range of total bacterial count was (1.5 × 10 2 -1.6 × 10 4 ) cfu/ml. The total coliform count (TCC m ) was recorded (14-40) in 100 ml of water samples. The presence of total coliform and fecal coliform was 26.32 and 18.42%, respectively, in PCR analysis but in biochemical test those were 18.42 and 15.78%, respectively. A total of 11 bacterial species: Enterobacter aerogenes, Escherrichia coli, Aeromonas, Bacillus sp., Cardiobacterium, Corynebacterium, Clostridium, Klebsiella sp., Lactobacillus, Micrococcus sp., Pseudomonas sp. were found. This study indicates that some of the drinking jar water samples were of poor quality which may increase the risk of water-borne disease. Hence, the producer of drinking jar water has to implement necessary quality control steps.

Epstein-Barr virus (EBV) vaccines have been developing for over 30 years, but polyphyletic and therapeutic vaccines have failed to get licensed. Our vaccine surpasses the limitations of many such vaccines and remains very promising, which is crucial because the infection rate is higher than most viral infections, affecting a whopping 90% of the adult population.

Five endophytic bacterial isolates were studied to identify morphologically and biochemically, according to established protocols and further confirmed by 16S rDNA Sanger sequencing, as Priestia megaterium, Staphylococcus caprae, Neobacillus drentensis, Micrococcus yunnanensis, and Sphingomonas paucimobiliz, which were then tested for phytohormone, ammonia, and hydrolytic enzyme production. Antioxidant compounds total phenolic content (TPC), and total flavonoid content (TFC) were assessed by using bacterial crude extracts obtained from 24-hour shake-flask culture. Phylogenetic tree analysis of those identified isolates shared sequence similarities with the members of Bacillus, Micrococcus, Staphylococcus, and Pseudomonas species, and after GenBank submission, accession numbers for the nucleotide sequences were found to be MW494406, MW494408, MW494401, MW494402, and MZ021340, respectively. In silico analysis was performed to identify their bioactive genes and compounds in the context of bioactive secondary metabolite production with medicinal value, where nine significant bioactive compounds according to six different types of bioactive secondary metabolites were identified, and their structures, gene associations, and protein-protein networks were analyzed by different computational tools and servers, which were reported earlier with their antimicrobial, anti-infective, antioxidant, and anti-cancer capabilities. These compounds were then docked to the 3-chymotrypsin-like protease (3CLpro) of the novel SARS-COV-2. Docking scores were then compared with 3CLpro reference inhibitor (lopinavir), and docked compounds were further subjected to ADMET and drug-likeness analyses. Ligand-protein interactions showed that two compounds (microansamycin and aureusimine) interacted favorably with coronavirus 3CLpro. Besides, in silico analysis, we also performed NMR for metabolite detection whereas three metabolites (microansamycin, aureusimine, and stenothricin) were confirmed from the 1H NMR profiles. As a consequence, the metabolites found from NMR data aligned with our in-silico analysis that carries a significant outcome of this research. Finally, Endophytic bacteria collected from medicinal plants can provide new leading bioactive compounds against target proteins of SARS-COV-2, which could be an effective approach to accelerate drug innovation and development.

Abundant, low prices and a highly reduced nature make glycerol to be an ideal feedstock for the production of reduced biochemicals and biofuels. Escherichia coli has been paid much attention as the platform of microbial cell factories due to its high growth rate (giving higher metabolite production rate) and the capability of utilizing a wide range of carbon sources. However, one of the drawbacks of using E. coli as a platform is its mixed metabolite formation under anaerobic conditions. In the present study, it was shown that ethanol could be exclusively produced from glycerol by the wild type E. coli, while d-lactic acid could be exclusively produced from glucose by pflA.cra mutant, where the glucose uptake rate could be increased by this mutant as compared to the wild type strain. It was also shown that the growth rate is significantly reduced in pflA.cra mutant for the case of using glycerol as a carbon source due to redox imbalance. The metabolic regulation mechanisms behind the fermentation characteristic were clarified to some extent.

Drinking water (unpackaged) samples were collected from twenty roadside shops of different locations in Chittagong metropolitan area, where physicochemical parameters (pH, TDS, temperature) were not exceeded WHO prescribed range in most cases. TVC, TCC, TFCC, TSC, Salmonella spp. and Vibrio spp. were found  contaminated as 85%, 70%, 50%, 20%, 30% and 75%, respectively. All the bacterial isolates (n=43) were found positive for 16S rDNA gene, while 12 isolates were coliform positive identified by lacZ gene amplification. Nine bacterial genera were finally identified depending on biochemical characteristics and two of them were further confirmed by 16S rDNA sequencing. Escherichia coli, Citrobacter spp., Klebsiella pneumoniae and Vibrio cholerae were resistant to amoxicillin, where all the bacterial isolates exhibited sensitivity to ciprofloxacin, gentamicin, imipenam and levofloxacin. Presence of human pathogenic and antibiotic resistant bacteria in unpackaged drinking water, suggested for increasing regular monitoring and public awareness to ensure public health safety Journal of Bangladesh Academy of Sciences, Vol. 42, No. 2, 137-153, 2018