Identification and Functional Characterization of Two Homologous SpoVS Proteins Involved in Sporulation of Bacillus thuringiensis

• Published in: Microbiology spectrum Vol. 9; no. 2; p. e0088121
• Main Authors: Liu, Xinlu, Zhang, Ruibin, Hou, Shuo, Liu, Huanhuan, Wang, Jiaojiao, Yu, Qingyue, Peng, Qi, Song, Fuping
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 31.10.2021
• Subjects: Bacillus thuringiensis; Bacillus thuringiensis - genetics; Bacillus thuringiensis - growth & development; Bacillus thuringiensis Toxins - biosynthesis; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; disporic septum; Endotoxins - biosynthesis; Gene Deletion; Gene Expression Regulation, Bacterial - genetics; Hemolysin Proteins - biosynthesis; Research Article; Sigma Factor - genetics; Sigma Factor - metabolism; Spores, Bacterial - growth & development; sporulation; spoVS; disporic septum; σH; Bacillus thuringiensis; spoVS; sporulation
• ISSN: 2165-0497; 2165-0497
• DOI: 10.1128/Spectrum.00881-21

Sporulation is an important part of the life cycle of Bacillus thuringiensis and the basis for the production of parasporal crystals. This study identifies and characterizes two homologous genes ( and ) in B. thuringiensis, both of whose expression is dependent on the σ factor. The disruption of and resulted in defective B. thuringiensis sporulation. Similar to Bacillus subtilis, B. thuringiensis strain HD(Δ ) mutants showed delayed formation of the polar septa, decreased sporulation efficiency, and blocked spore release. Different from B. subtilis, B. thuringiensis HD(Δ ) mutants had disporic septa and failed to complete engulfment in some cells. Moreover, HD(Δ ) mutants had delayed spore release. The effect of deletion on polar septum delay and sporulation efficiency could be compensated by . β-Galactosidase activity analysis showed that the expression of pro- and decreased to different degrees in the HD(Δ ) and HD(Δ ) mutants. The different effects of the two mutations on the expression of sporulation genes led to decreases in Cry1Ac production of different levels. There is only one gene in B. subtilis, and its effects on sporulation have been reported. In this study, two homologous genes were found and identified in B. thuringiensis. The different effects on sporulation and parasporal crystal protein production in B. thuringiensis and their relationship were investigated. We found that these two homologous genes are highly conserved in the Bacillus cereus group, and therefore, the functional characterization of SpoVS is helpful to better understand the sporulation processes of members of the Bacillus cereus group.