Expression, Folding, and Activation of Halophilic Alkaline Phosphatase in Non-Halophilic Brevibacillus choshinensis

Insights into effects of salt stress on the oil-degradation capacity, cell response, and key metabolic pathways of Bacillus sp. YM1 isolated from oily food waste compost

A novel bacterial strain, Bacillus sp. YM1, was isolated from compost for the efficient degradation of oily food waste under salt stress. The strain's lipase activity, oil degradation ability, and tolerance to salt stress were evaluated in a liquid medium. Additionally, the molecular mechanisms (including key genes and functional processes) underlying the strain's salt-resistant degradation of oil were investigated based on RNA-Seq technology. The results showed that after 24 h of microbial degradation, the degradation rate of triglycerides in soybean oil was 80.23% by Bacillus sp. YM1 at a 30 g L-1 NaCl concentration. The metabolizing mechanism of long-chain triglycerides (C50-C58) by the YM1 strain, especially the biodegradation rate of triglycerides (C18:3/C18:3/C18:3), could reach 98.65%. The most substantial activity of lipase was up to 325.77 U·L-1 at a salinity of 30 g L-1 NaCl. During salt-induced stress, triacylglycerol lipase was identified as the crucial enzyme involved in oil degradation in Bacillus sp. YM1, and its synthesis was regulated by the lip gene (M5E02_13495). Bacillus sp. YM1 underwent adaptation to salt stress through various mechanisms, including the accumulation of free amino acids, betaine synthesis, regulation of intracellular Na+/K+ balance, the antioxidative response, spore formation, and germination. The key genes involved in Bacillus sp. YM1's adaptation to salt stress were responsible for the synthesis of glutamate 5-kinase, superoxide dismutase, catalase, Na+/H+ antiporter, general stress protein, and sporogenic proteins belonging to the YjcZ family. Results indicated that the isolated strain of Bacillus sp. YM1 could significantly degrade oil in a short time under salt stress. This study would introduce new salt-tolerant strains for coping with the biodegradation of oily food waste and provide gene targets for use in genetic engineering.

Isolation and identification of high-yielding alkaline phosphatase strain: a novel mutagenesis technique and optimization of fermentation conditions

Isolating and screening enzyme-producing strains from microorganisms and the commercial production of ALPs from microorganisms are of increasing interest. In this work, isolation and identification of high-yielding alkaline phosphatase strain were carried out using atmospheric and room temperature plasma mutagenesis (ARTP) for optimization of fermentation conditions. A strain of alkaline phosphatase-producing bacteria was screened from soil and identified by 16S rRNA gene sequencing as Bacillus amyloliquefaciens and named S-1. This strain had an alkaline phosphatase activity of 2594.73 U/L. Later, mutagenesis breeding of the alkaline phosphatase-producing S-1 strain was conducted using (ARTP), from which a higher alkaline phosphatase-producing positive mutant strain S-52 was screened. A central combination of five factors, including corn starch, yeast extract, metal ions, fermentation temperature and inoculum ratio, was then used to influence the activity of alkaline phosphatase. Results from the response surface methodology showed that the maximum enzyme activity of alkaline phosphatase was 12,110.6 U/L at corn starch, yeast extract and magnesium ions concentrations of 17.48 g/L, 18.052 g/L and 0.744 g/L, respectively; fermentation temperature of 37.192 °C; and inoculation ratio of 5.59%. This study is important for further exploring ARTP mutagenesis in B. amyloliquefaciens and the commercialization of ALPs.

Available strategies for improved expression of recombinant proteins in Brevibacillus expression system: a review

Brevibacillus offers great potential as a recombinant protein expression host because of its exceptional abilities to synthesize and excrete proteins and its low extracellular protease activity. Despite these strengths, effective recombinant expression strategies are still the key to achieving high-level expression of recombinant proteins in Brevibacillus due to individual differences among strains and target proteins. Many strategies have been developed to improve recombinant protein expression in Brevibacillus. This review begins by introducing the processes used to establish and apply the Brevibacillus expression system, and then critically discusses the strategies available for improving recombinant protein expression in Brevibacillus, including optimization of the host and the expression vector, co-expression of a fusion partner or foldase, and optimization of the fermentation process. Finally, the prospects for further improvement of recombinant protein expression based on Brevibacillus are also discussed. This review is intended to provide a strategic reference for scientists wanting to improve the expression of a specific recombinant protein in Brevibacillus or other expression systems.