Comparative mutational analysis of SARS-CoV-2 isolates from Pakistan and structural-functional implications using computational modelling and simulation approaches.

SARS-CoV-2, an RNA virus, has been prone to high mutations since its first emergence in Wuhan, China, and throughout its spread. Its genome has been sequenced continuously by many countries, including Pakistan, but the results vary. Understanding its genomic patterns and connecting them with phenotypic features will help in devising therapeutic strategies. Thus, in this study, we explored the mutation landscape of 250 Pakistani isolates of SARS-CoV-2 genomes to check the genome diversity and examine the impact of these mutations on protein stability and viral pathogenesis in comparison with a reference sequence (Wuhan NC 045512.2). Our results revealed that structural proteins mainly exhibit more mutations than others in the Pakistani isolates; in particular, the nucleocapsid protein is highly mutated. In comparison, the spike protein is the most mutated protein globally. Furthermore, nsp12 was found to be the most mutated NSP in the Pakistani isolates and worldwide. Regarding accessory proteins, ORF3A is the most mutated in the Pakistani isolates, whereas ORF8 is highly mutated in world isolates. These mutations decrease the structural stability of their proteins and alter different biological pathways. Molecular docking, the dissociation constant (KD), and MM/GBSA analysis showed that mutations in the S protein alter its binding with ACE2. The spike protein mutations D614G-S943T-V622F (-75.17 kcal/mol), D614G-Q677H (-75.78 kcal/mol), and N74K-D614G (-73.84 kcal/mol) exhibit stronger binding energy than the wild type (-66.34 kcal/mol), thus increasing infectivity. Furthermore, the simulation results strongly corroborated the predicted protein servers. Our analysis findings also showed that E, M, ORF6, ORF7A, ORF7B, and ORF10 are the most stable coding genes; they may be suitable targets for vaccine and drug development.

Enhanced production of maltase (α-glucosidase) from newly isolated strain of Bacillus licheniformis KIBGE-IB4.

Maltase (alpha-glucosidase) hydrolyzes α-(1→4) glucosidic bond of maltose into two glucose molecules. It is widely used in various foods, beverages and also in textile and biofuel industries. During current study, various physicochemical parameters for maltase production from newly isolated strain of Bacillus licheniformis KIBGE-IB4 were optimized using one-factor-at-a-time methodology. It was found that Bacillus licheniformis KIBGE-IB4 produced maximum maltase at 37°C, pH-7.0 after 48 hours using wheat starch (2.5%) as carbon source along with peptone (1.0%), yeast extract (0.2%) and meat extract (0.4%) as nitrogen sources in fermentation medium. It is concluded that the optimization of various medium ingredients and conditions increases maltase production upto 6.74 fold from B. licheniformis KIBGE-IB4 as compared to previously reported media and this strain could be used for the commercial production of maltase.