Effects of substrate binding site residue substitutions of xynA from Bacillus amyloliquefaciens on substrate specificity

Abstract Background The aromatic residues of xylanase enzyme, W187, Y124, W144, Y128 and W63 of substrate binding pocket from Bacillus amyloliquefaciens were investigated for their role in substrate binding by homology modelling and sequence analysis. These residues are highly conserved and play an important role in substrate binding through steric hindrance. The substitution of these residues with alanine allows the enzyme to accommodate nonspecific substrates. Results Wild type and mutated genes were cloned and overexpressed in BL21. Optimum pH and temperature of rBAxn exhibited pH 9.0 and 50 °C respectively and it was stable up to 215 h. Along with the physical properties of rBAxn, kinetic parameters (K m 19.34 ± 0.72 mg/ml; k cat 6449.12 ± 155.37 min− 1 and k cat /K m 333.83 ± 6.78 ml min− 1 mg− 1) were also compared with engineered enzymes. Out of five mutations, W63A, Y128A and W144A lost almost 90% activity and Y124A and W187A retained almost 40–45% xylanase activity. Conclusions The site-specific single mutation, led to alteration in substrate specificity from xylan to CMC while in case of double mutant the substrate specificity was altered from xylan to CMC, FP and avicel, indicating the role of aromatic residues on substrate binding, catalytic process and overall catalytic efficiency

Exploring the Impact of COVID-19 and the Associated Lockdown on the Production, Distribution, and Consumption of Poultry Products in Gujarat, India: A Qualitative Study

Background: The poultry industry in India, estimated to be worth about one trillion INR, was severely affected by the COVID-19 pandemic. This study was conducted in Gujarat, India to unpack the processes through which COVID-19-related factors affected the poultry production and distribution network and explore the impacts on the relevant actors. Methods: An exploratory qualitative study was conducted among 34 poultry stakeholders using semi-structured interviews. The data were thematically analyzed by adopting an interpretative phenomenological approach. Results: Convincing evidence emerged that the lockdown and the pandemic significantly impacted the production, distribution, and consumption of poultry products. Movement restrictions during the first lockdown disrupted the supply of inputs and the distribution of poultry and poultry products. Between March and June 2020, rumors contributed to a substantial decrease in the consumption of poultry products. Consumption picked up following the reopening after the lockdown and the prices and availability of poultry products. The profits, however, failed to compensate for the losses that had been incurred. Conclusions: The experience and impacts of the first COVID-19 lockdown on the poultry industry unraveled several short- and medium-term challenges in the poultry sector in India that need to be addressed to make it more resilient to similar shocks

Additional file 1: of Effects of substrate binding site residue substitutions of xynA from Bacillus amyloliquefaciens on substrate specificity

Table S1. Primer sequences used for the fragment generation. Figure S1. BLAST analysis and sequence alignment of xylanase with available online database using UniprotKb alignment tool. Red color shows reported active site residues and yellow color displays the location of active residues present in the XYNA of Bacillus amyloliquefaciens. Orange color indicates conserved aromatic residues across the family of xylanase enzymes. The black color boxes display the selected aromatic amino acid residues for single mutation in XYNA of Bacillus amyloliquefaciens. (DOCX 1540 kb