Balsanelli Eduardo, de Baura Válter Antonio, Pedrosa Fábio de Oliveira, de Souza Emanuel Maltempi, Monteiro Rose Adele
Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, Paraná, Brazil.
PLoS One. 2014 Oct 13;9(10):e110392. doi: 10.1371/journal.pone.0110392. eCollection 2014.
H. seropedicae associates endophytically and epiphytically with important poaceous crops and is capable of promoting their growth. The molecular mechanisms involved in plant colonization by this microrganism are not fully understood. Exopolysaccharides (EPS) are usually necessary for bacterial attachment to solid surfaces, to other bacteria, and to form biofilms. The role of H. seropedicae SmR1 exopolysaccharide in biofilm formation on both inert and plant substrates was assessed by characterization of a mutant in the espB gene which codes for a glucosyltransferase. The mutant strain was severely affected in EPS production and biofilm formation on glass wool. In contrast, the plant colonization capacity of the mutant strain was not altered when compared to the parental strain. The requirement of EPS for biofilm formation on inert surface was reinforced by the induction of eps genes in biofilms grown on glass and polypropylene. On the other hand, a strong repression of eps genes was observed in H. seropedicae cells adhered to maize roots. Our data suggest that H. seropedicae EPS is a structural component of mature biofilms, but this development stage of biofilm is not achieved during plant colonization.
血清芽孢杆菌（H. seropedicae）以内生和附生的方式与重要的禾本科作物共生，并能够促进它们的生长。这种微生物定殖于植物的分子机制尚未完全了解。胞外多糖（EPS）通常是细菌附着于固体表面、其他细菌以及形成生物膜所必需的。通过对编码葡糖基转移酶的espB基因中的一个突变体进行表征，评估了血清芽孢杆菌SmR1胞外多糖在惰性和植物基质上生物膜形成中的作用。该突变菌株在EPS产生和玻璃棉上的生物膜形成方面受到严重影响。相比之下，与亲本菌株相比，突变菌株的植物定殖能力没有改变。在玻璃和聚丙烯上生长的生物膜中eps基因的诱导增强了在惰性表面形成生物膜对EPS的需求。另一方面，在附着于玉米根的血清芽孢杆菌细胞中观察到eps基因受到强烈抑制。我们的数据表明，血清芽孢杆菌EPS是成熟生物膜的结构成分，但在植物定殖过程中并未达到生物膜的这个发育阶段。
