Dr. Mohammad Minnatul Karim

Buruli ulcer is an emerging-necrotizing skin infection, responsible for permanent deformity if untreated, caused by the pathogen Mycobacterium ulcerans (M. ulcerans). Despite this debilitating condition, no specific disease-modifying therapeutics or vaccination is available. Therefore, we aimed to design an effective multi-epitope vaccine against M. ulcerans through an integrated vaccinomics approach. Briefly, the highest antigenic PE-PGRS protein was selected from which the promiscuous T- and B-cell epitopes were predicted. After rigorous assessment, 15 promising CTL, HTL and LBL epitopes were selected. The identified T-cell epitopes showed marked interactions towards the HLA binding alleles and provided 99.8% world population coverage. Consequently, a vaccine chimera was designed by connecting these epitopes with suitable linkers and adjuvant (LprG). The vaccine construct was antigenic and immunogenic as well as non-allergenic; hence, subjected to homology modelling. The molecular...

Elizabethkingia anophelis is an emerging human pathogen causing neonatal meningitis, catheter-associated infections and nosocomial outbreaks with high mortality rates. Besides, they are resistant to most antibiotics used in empirical therapy. In this study, therefore, we used immunoinformatic approaches to design an epitope-based vaccine against E. anophelis as an alternative preventive measure. Initially, T-cell (CTL and HTL) and B-cell (LBL) epitopes were predicted from the highest antigenic protein. The CTL and HTL epitopes together had a population coverage of 99.97% around the world. Eventually, 6 CTL, 7 HTL, and 2 LBL epitopes were selected and used to construct a multiepitope vaccine. The vaccine protein was found to be highly immunogenic, non-allergenic, and non-toxic. Codon adaptation and in silico cloning were performed to ensure better expression within E. coli K12 host system. The stability of the vaccine structure was also improved by disulphide bridging. In addition, m...

Background: Biofilm is a surface adhered extracellular polymer matrix produced by bacteria. The establishment of biofilms is considered as an important pathogenic trait in many chronic infections and antibiotic resistance. Objective: The present study was intended to evaluate biofilm forming potency and antibiotic resistance (AR) pattern in clinical and non-clinical bacterial isolates, and their phylogenetic characterization. Materials and Methods: A total of 82 bacterial isolates were obtained from clinical settings and animal farms from southern (Kushtia-Jhenaidah) region of Bangladesh. Biofilm forming potentials and AR profile were evaluated by standard biofilm assay and Kirby-Bauer disk diffusion method, respectively. Further, antibiotic exposure was assessed by multiple antibiotic resistance (MAR) value indexing. Furthermore, statistical methods were applied to estimate the relationship between AR and biofilm formation. Finally, selected isolates were characterized by morpholog...

Quorum sensing (QS) enables virulence factors in bacteria for biofilm formation and pathogenic invasion. Therefore, quorum quenching (QQ), disruption of QS circuit, becomes an alternative antimicrobial therapy. In this study, leaf extract of Gynura procumbens (GP) was used to inhibit biofilm and virulent factors in Pseudomonas aeruginosa. The extract inhibited the biofilm production (p ≤ 0.05) in P. aeruginosa strains MZ2F and MZ4A. The minimum biofilm eradication concentration (MBEC) was recorded at 250 and 500 μg/ml while total activity was found at 288 and 144 ml/g, respectively. Moreover, a significant reduction of virulence factors (p ≤ 0.05) at sub-MBEC without affecting the growth implies the QQ action of the extract. The bioactive fractions were rich in polyphenols and tentatively identified as quercetin and myricetin (R f =0.53-0.60). Furthermore, we employed computational methods to validate our findings and their interactions with QS receptors (LasR and RhlR). Interestingly, docking studies have also shown that quercetin and myricetin are the promising anti-QS agents out of 31 GP compounds. Notably, their binding affinity ranged between -9.77 and -10.52 kcal/mol for both QS receptors, with controls ranging from -5.40 to -8.97 kcal/mol. Besides, ΔG of quercetin and myricetin with LasR was -71.56 and -74.88 kcal/mol, respectively. Moreover, compounds were suitable drug candidates with stable binding interactions. Therefore, the anti-QS activity of GP leaves and the identified polyphenols can be used in developing QQ-based therapeutics. Communicated by Ramaswamy H. Sarma.

Pseudomonas aeruginosa is a human opportunistic pathogen known to build biofilm and is able to proliferate within the biofilm. Antibacterial substances are of natural origin, and it is thought that their influences on the environment are important and can be used as biological control agents. In the present study, multi-drug resistant and the high yielding biofilm Pseudomonas aeruginosa strains have been isolated from the hospital waste. Multi-drug resistance pattern was studied with disc diffusion assay using commercially available antibiotic discs. Ten isolates were multi-drug resistant among eighteen isolates. Modified crystal violet staining method was performed to know the ability of biofilm formation by isolated strains. All of the isolates were able to form biofilm except one. Antibiofilm and Antimicrobial activity of medicinal plants Centella asiatica (Thankuni), Mentha spicata (Mentha), Azadirachta indica (Neem), Psidium guajava (Guava) and spices Syzygium aromaticum (Clove...

Despite the association of prevalent health conditions with coronavirus disease 2019 (COVID-19) severity, the disease-modifying biomolecules and their pathogenetic mechanisms remain unclear. This study aimed to understand the influences of COVID-19 on different comorbidities and vice versa through network-based gene expression analyses. Using the shared dysregulated genes, we identified key genetic determinants and signaling pathways that may involve in their shared pathogenesis. The COVID-19 showed significant upregulation of 93 genes and downregulation of 15 genes. Interestingly, it shares 28, 17, 6 and 7 genes with diabetes mellitus (DM), lung cancer (LC), myocardial infarction and hypertension, respectively. Importantly, COVID-19 shared three upregulated genes (i.e. MX2, IRF7 and ADAM8) with DM and LC. Conversely, downregulation of two genes (i.e. PPARGC1A and METTL7A) was found in COVID-19 and LC. Besides, most of the shared pathways were related to inflammatory responses. Furt...

Silk sericin (SS) was extracted from Bombyx mori silkworm cocoons in an aqueous medium. 17 w/w% of dry sericin powder with respect to the cocoon’s weight was obtained by freeze drying. The extracted sericin exhibited excellent hydrophilicity, biodegradability, and reducing properties. Furthermore, silver nanoparticles conjugated to sericin, i.e., SS-capped silver nanoparticles (SS-AgNPs) were synthesized by easy, cost effective, and environment-friendly methods. The synthesized SS-AgNPs were characterized by UV-visible spectroscopy, Fourier-transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction measurement. It has been found from the absorbance of UV-visible spectroscopy that a higher parent of SS-AgNPs was obtained at a higher concentration of silver nitrate solution. FTIR-ATR spectra showed that the carboxylate groups obtained from silk sericin act as a reducing agent for the synthesis of silver nanopar...

In this study, we investigated the effect of long-term pesticides and chemical fertilizers application on the microbial communities specifically anammox and denitrification bacteria in rice field soils. The abundances of microbial communities (16S rDNA), anammox ( hszB ), and denitrification ( narG, nirK, nirS, and nosZ ) genes were quantified by q -PCR. 10 pesticides (5 insecticides, 3 fungicides and 2 herbicides) and chemical fertilizers urea, potassium, phosphate, DAP (di-ammonium phosphate), gypsum, and boric acid were used by local farmers. Nitrate, SOC (ammonia, soil organic carbon), N and C content significantly ( p  < 0.05) decreased in the rice field soils as compared to the upland soils. Abundance of 16S rDNA, hszB, narG, nirK, nirS , and nosZ genes significantly ( p  < 0.05) decreased in the rice field soils and positively correlated with chemical properties of soils. Our results provide useful information and further maintenance should be instilled to the potential of chemical and biological factors decreased in rice field soils.

ABSTRACT: Over 60% of the global productions of industrial enzymes are proteolytic enzymes in which about 35% are alkaline proteases. The current microbial sources are unable to reach industrial demands of alkaline protease which led scientists to search new sources with enhanced enzyme activity. Therefore, we applied UV irradiation to develop a Pseudomonas aeruginosa mutant as a new source of protease overproduction, followed by cultural and nutritional optimizations. The mutagenesis was carried out by exposing parent strains to UV radiation (30w, 2537 Å) at 25 ºC with a different time interval. The protease activity was estimated as relative protease activity and standard protease assay (OD660). Among all, mutant strain P. aeruginosa-M25 (PA-M25) exhibited 75.47% increased protease activity over the parent strain in submerged fermentation. It showed 612.84±2.50 U/ml of alkaline protease production compared to 349.26±2.57 U/ml by wild-type strain (significant at P≤0.005). Besides, ...

With the emergence of multidrug-resistant ‘superbug’, conventional treatments become obsolete. Quorum quenching (QQ), enzyme-dependent alteration of quorum sensing (QS), is now considered as a promising antimicrobial therapy because of its potentiality to impede virulence gene expression without resulting in growth inhibition and antibiotic resistance. In our study, we intended to compare between two major QQ enzyme groups (i.e., AHL lactonases and AHL acylases) in terms of their structural and functional aspects. The amino acid composition-based principal component analysis (PCA) suggested that probably there is no structural and functional overlapping between the two groups of enzymes as well as within the lactonase enzymes but the acylases may functionally be affected by one another. In subcellular localization analysis, we also found that most lactonases are cytoplasmic while acylases are periplasmic. Investigation on the secondary structural features showed random coil dominates over α-helix and β-sheet in all evaluated enzymes. For structural comparison, the tertiary structures of the selected proteins were modelled and submitted to the PMDB database (Accession ID: PM0081007 to PM0081018). Interestingly, sequence alignment revealed the presence of several conserved domains important for functions in both protein groups. In addition, three amino acid residues, namely aspartic acid, histidine, and isoleucine, were common in the active sites of all protein models while most frequent ligands were found to be 3C7, FEO, and PAC. Importantly, binding interactions of predicted ligands were similar to that of native QS signal molecules. Furthermore, hydrogen bonds analysis suggested six proteins are more stable than others. We believe that the knowledge of this comparative study could be useful for further research in the development of QS-based universal antibacterial strategies.

Abstract Elizabethkingia anophelis is an emerging human pathogen causing neonatal meningitis, catheter-associated infections and nosocomial outbreaks with high mortality rates. Besides, they are resistant to most antibiotics used in empirical therapy. In this study, therefore, we used immunoinformatic approaches to design a prophylactic peptide vaccine against E. anophelis as an alternative preventive measure. Initially, cytotoxic T-lymphocyte (CTL), helper T-lymphocyte (HTL), and linear B-lymphocyte (LBL) epitopes were predicted from the highest antigenic protein. The CTL and HTL epitopes together had a population coverage of 99.97% around the world. Eventually, six CTL, seven HTL, and two LBL epitopes were selected and used to construct a multi-epitope vaccine. The vaccine protein was found to be highly immunogenic, non-allergenic, and non-toxic. Codon adaptation and in silico cloning were performed to ensure better expression within E. coli K12 host system. The stability of the vaccine structure was also improved by disulphide bridging. In addition, molecular docking and dynamics simulation revealed strong and stable binding affinity between the vaccine and toll-like receptor 4 (TLR4) molecule. The immune simulation showed higher levels of T-cell and B-cell activities which was in coherence with actual immune response. Repeated exposure simulation resulted in higher clonal selection and faster antigen clearance. Nevertheless, experimental validation is required to ensure the immunogenic potency and safety of this vaccine to control E. anophelis infection in the future. Communicated by Ramaswamy H. Sarma

Pseudomonas aeruginosa is an emerging opportunistic pathogen responsible for cystic fibrosis and nosocomial infections. In addition, empirical treatments are become inefficient due to their multiple-antibiotic resistance and extensive colonizing ability. Quorum sensing (QS) plays a vital role in the regulation of virulence factors in P. aeruginosa. Attenuation of virulence by QS inhibition could be an alternative and effective approach to control infections. Therefore, we sought to discover new QS inhibitors (QSIs) against LasR receptor in P. aeruginosa using chemoinformatics. Initially, a structure-based high-throughput virtual screening was performed using the LasR active site that identified 61404 relevant molecules. E-pharmacophore (ADAHH) screening of these molecules rendered 72 QSI candidates. In standard-precision docking, only 7 compounds were found as potential QSIs due to their higher binding affinity to LasR receptor (-7.53 to -10.32 kcal/mol compared to -7.43 kcal/mol of...

Background: Paper currency is used for every type of commerce and plays an important role in the life of human beings. They are exchanged and come into contact with different environments and many different individuals during their circulation. Therefore, they can become contaminated with microorganisms and transfer bacteria across environments. The present study was aimed for quantitative assessment of microorganisms in circulated paper currency from Kushtia, Bangladesh and antibiotic resistant profiles of isolated Escherichia coli.Methods: A total of 10 paper currency samples currently in circulation involving three denominations (5, 10 and 500) were randomly collected from individuals involved in various occupations including street beggar, local hotel, bus conductor, poultry seller, vegetable seller, fish seller, commercial bank, ATM booth, tea seller, grocery store in Kushtia city, Bangladesh. Selective culture and biochemical tests were performed for the isolation and identifi...

Various medicinal plants are used to prevent or cure infectious diseases as an alternative solution to antibiotics. In this study, Swietenia mahagoni (Seed) was selected and antibacterial activity of extracts with various solvents (Petroleum Ether, Ethyl Acetate, Dichloromethane, and Methanol) was studied in laboratory test. The antibacterial activity of these extracts was assessed against Bacillus subtillis, Sarcina lutea, Xanthomonas campestris, Klebsiella pneumoniae, Escherichia coli and unidentified kidney infectious bacteria based on the zone of inhibition using Agar disc diffusion method. The antibacterial activity among extracts was broad against both gram positive and gram negative microorganisms. Among the various solvents extract, both ethyl acetate and methanol extract was more active against tested organisms. The results suggested that Swietenia mahagoni (Seed) has phytochemicals which are active against broad spectrum bacteria and both methanol and ethyl acetate could b...