Comparative analysis of structural variations due to genome shuffling of Bacillus subtilis VS15 for improved cellulase production

Cellulose is one of the most abundant and renewable biomass products used for the production of bioethanol. Cellulose can be efficiently hydrolyzed by Bacillus subtilis VS15, a strain isolate obtained from decomposing logs. A genome shuffling approach was implemented to improve the cellulase activity of Bacillus subtilis VS15. Mutant strains were created using ethyl methyl sulfonate (EMS), N-Methyl-N′ nitro-N-nitrosoguanidine (NTG), and ultraviolet light (UV) followed by recursive protoplast fusion. After two rounds of shuffling, the mutants Gb2, Gc8, and Gd7 were produced that had an increase in cellulase activity of 128%, 148%, and 167%, respectively, in comparison to the wild type VS15. The genetic diversity of the shuffled strain Gd7 and wild type VS15 was compared at whole genome level. Genomic-level comparisons identified a set of eight genes, consisting of cellulase and regulatory genes, of interest for further analyses. Various genes were identified with insertions and deletions that may be involved in improved celluase production in Gd7.. Strain Gd7 maintained the capability of hydrolyzing wheatbran to glucose and converting glucose to ethanol by fermentation with Saccharomyces cerevisiae of the wild type VS17. This ability was further confirmed by the acidified potassium dichromate (K2Cr2O7) method

Microbial Fuel Cells, Related Technologies, and Their Applications

Microbial fuel cells present an emerging technology for utilizing the metabolism of microbes to fuel processes including biofuel, energy production, and the bioremediation of environments. The application and design of microbial fuel cells are of interest to a range of disciplines including engineering, material sciences, and microbiology. In addition, these devices present numerous opportunities to improve sustainable practices in different settings, ranging from industrial to domestic. Current research is continuing to further our understanding of how the engineering, design, and microbial aspects of microbial fuel cell systems impact upon their function. As a result, researchers are continuing to expand the range of processes microbial fuel cells can be used for, as well as the efficiency of those applications