Department of Microbiology, Faculty of Biology, University of Bialystok, Bialystok, Poland.
Department of Microbiology, Faculty of Biology, University of Bialystok, Bialystok, Poland.
Syst Appl Microbiol. 2020 May;43(3):126075. doi: 10.1016/j.syapm.2020.126075. Epub 2020 Mar 4.
Bacillus cereus s.l., Gram-positive endospore-forming bacilli, persist ubiquitously in different natural habitats and play various ecological roles. Nevertheless, although chitin is one of the most abundant polymer on Earth, the study of the ability of B. cereus s.l. to hydrolyze this polymer were limited to individual B. cereus and B. thuringiensis strains only. Thus, to fill this gap in this research we focused on (i) the linkage between the capability to chitin degradation and the phylogenetic relatedness of B. cereus s.l. strains, and (ii) the genetic background of chitinolytic properties of these bacilli. Our results showed that chitin degradation is common among the B. cereus group members, yet strains clustered into particular phylogenetic groups differ in their chitinolytic capacity. Separate clustering of chitinolytic and non-chitinolytic strains in the phylogenetic tree indicates the ecotypic structure of these isolates. Two proteins belonging to subfamily A (ChiA) and subfamily B (ChiB) of the glycoside hydrolase GH18 family exhibited simultaneous chitobiosidase and endochitinase activities, and are responsible for chitin utilization by environmental B. cereus s.l. isolates.
解淀粉芽孢杆菌 s.l.，革兰氏阳性内生孢子形成杆菌，普遍存在于不同的自然栖息地，并发挥着各种生态作用。然而，尽管几丁质是地球上最丰富的聚合物之一，但对解淀粉芽孢杆菌 s.l. 水解这种聚合物的能力的研究仅限于个别解淀粉芽孢杆菌和苏云金芽孢杆菌菌株。因此，为了填补这一研究空白，我们重点研究了：（i）几丁质降解能力与解淀粉芽孢杆菌 s.l. 菌株系统发育相关性之间的联系；（ii）这些杆菌解几丁质特性的遗传背景。研究结果表明，几丁质降解在解淀粉芽孢杆菌群成员中很常见，但聚类到特定系统发育群的菌株在几丁质降解能力上存在差异。几丁质降解和非几丁质降解菌株在系统发育树上的单独聚类表明了这些分离物的生态型结构。属于糖苷水解酶 GH18 家族亚家族 A（ChiA）和亚家族 B（ChiB）的两种蛋白同时表现出壳二糖酶和内切几丁质酶活性，负责环境解淀粉芽孢杆菌 s.l. 分离物对几丁质的利用。
