Surfactin variants mediate species‐specific biofilm formation and root colonization in Bacillus

Abstract

Cyclic lipopeptides (cLP) and especially surfactins produced by Bacillus spp. trigger biofilm formation and root colonization and are crucial for biocontrol activity and systemic resistance in plants. Bacillus atrophaeus 176s isolated from the moss Tortella tortuosa produces the cLP fengycins, iturins and surfactins, possesses antifungal activities and can protect tomato, lettuce and sugar beet against Rhizoctonia solani infection. In B. atrophaeus we identified for the first time the variant surfactin C, which differs from surfactin A produced by B. subtilis and B. amyloliquefaciens by an isoleucine instead of a leucine at position 7 of the lipopeptide backbone. The analysis of the complete surfactin gene clusters revealed that the dissimilarity is encoded in the adenylation domain of srfC and show that surfactin variations are distributed in a species-specific manner in bacilli. We demonstrate that the surfactin A and C with subtle structural differences have varying signal strengths on biofilm formation and root colonization and act specifically on the respective producing strain. This became evident as biofilm formation and root colonization but not swarming motility in surfactin biosynthesis mutants was restored differentially in the presence of exogenously supplemented cognate and non-cognate surfactin variants.

A single mutation in rapP induces cheating to prevent cheating in Bacillus subtilis by minimizing public good production

“…The virtual absence of N236 mutations in B. subtilis strains is surprising (Table 3), and could be a result of other cheater protection mechanisms at work, such as the diversification of surfactants in the subtilis clade 92,93 (though this diversity was shown to affect biofilms more than swarms 94 ). It may also suggest that NCIB 3610, the supposedly wild strain commonly used in lab studies, is likely at least partially domesticated from its original Marburg ancestor 75 based on a recent genomic analysis that found an amount of gene loss similar to that of lab strains 95 .…”

Stress-Responsive Alternative Sigma Factor SigB Plays a Positive Role in the Antifungal Proficiency of Bacillus subtilis

“…In addition, surfactins are very important molecules for the proficiency of bacilli at establishing robust and persistent beneficial biofilms in the plant rhizosphere ( Fig. 7C) and work synergistically with fengycins and bacillomycins (a member of the iturin family) against fungi (57)(58)(59). Additionally, surfactins, but not iturins or fengycins, are able to induce plant systemic resistance (ISR) against pathogens (Fig.…”

Bacillus subtilis and surfactin inhibit the transmissible gastroenteritis virus from entering the intestinal epithelial cells

“…By this amphiphilic structure, surfactin is one of the strongest biosurfactants. Studies on surfactin are focused on properties against phytopathogenic microorganisms, such as antibacterial [7], antifungal [8], inhibition of fibre clot formation [9] and antiviral [10,11] ability. Some reports showed that surfactin could inactivate various enveloped virus, like vesicular stomatitis virus (VSV, rhabdoviridae) and suid herpes virus type 1 (SHV-1, pseudorabies virus) , by inserting into the outer layer of lipid membrane bilayer so that the envelope disintegrates [12].…”