Specific Bacillus subtilis 168 variants do form biofilms on nutrient rich medium.

Microbiology (Reading, England)

PubMedID: 27655338

Gallegos-Monterrosa R, Mhatre E, Kovacs AT. Specific Bacillus subtilis 168 variants do form biofilms on nutrient rich medium. Microbiology (Reading, Engl). 2016;.
Bacillus subtilis is an intensively studied Gram-positive bacterium that has become one of the models for biofilm development. B. subtilis 168 is a well-known domesticated strain that has been suggested to be deficient in robust biofilm formation. Moreover, the diversity of available B. subtilis laboratory strains and their derivatives has made it difficult to compare independent studies related to biofilm formation. Here, we have analyzed numerous 168 stocks from multiple laboratories for their ability to develop biofilms in different setups and media. We report a wide variation among the biofilm-forming capabilities of diverse stocks of B. subtilis 168, both in architecturally complex colonies and liquid-air interphase pellicles, as well as during plant root colonization. Some 168 variants are indeed unable to develop robust biofilm structures, while others do so as efficiently as the undomesticated NCIB 3610 strain. In all studied cases, the addition of glucose to the medium dramatically improves biofilm development of the laboratory strains. Furthermore, the expressions of biofilm matrix component operons, epsA-O and tapA-sipW-tasA were monitored during colony biofilm formation. We find lack of direct correlation between the expression of these genes and the complexity of wrinkles in colony biofilms. However, the presence of a single mutation in the EPS-related gene epsC does correlates with the ability of the tested stocks to form architecturally complex colonies, pellicles, and to colonize plant roots.