Biology subjects

Stannius, R. O.

Publications and source records attributed to Stannius, R. O..

3 recordsLinked to original sources

bioRxiv2024

Plipastatin is a shared good by Bacillus subtilis during combating Fusarium spp.

Bacillus subtilis a Gram-positive soil dwelling bacterium known for its wide range of bioactive secondary metabolites. The lipopeptide plipastatin produced by most B. subtilis isolates have been shown to exhibit potent anti-fungal activity against plant pathogenic fungi. While the effect of these anti-fungal compounds are well studied in the context of biocontrol, much less is known of their role in the environment, which also harbor non-producing strains of these compounds. Fusarium species produce multiple antibacterial compounds resulting in dysbiosis of the plant-associated microbiome and inhibiting plant beneficial bacteria like B. subtilis. While plipastatin is expected to be important for survival of B. subtilis, not all isolates carry the biosynthetic gene cluster for plipastatin suggesting that the protective effect of plipastatin might be shared. In this study, we investigated the protective effect of plipastatin against Fusarium oxysporum in a co-culture using a producer and a non-producer isolate of plipastatin. We tested the survival of single and co-cultured strains under Fusarium challenge in liquid media and solid agar plates to dissect the influence of spatial structure. Our results highlights that plipastatin protects the non-producer strain in a density dependent manner.

microbiology↗

bioRxiv2024

Characterization of widely conserved novel pigment production in Bacillus subtilis species

Bacillus subtilis is widely studied in the microbial secondary metabolite (SM) field due to its rich variety of important natural products and genetic tractability. However, identification of novel SMs and their biosynthetic gene cluster (BGCs) has become increasingly difficult, especially in Bacilli, as the tools for screening and genome mining are dependent on clear function or similarity to already known BGCs. Pigments are SMs identified by their absorption of visible light, resulting in a certain color perceived by our eyes at sufficient concentrations. Thereby, pigments provide the evidence of a BGC without knowing the sequence or function. Expanding the known repertoire of SM BGCs with novel BGCs will further reinforce identification of a broader set of BGCs by mining tools such as antiSMASH. Here, we study a pigment observed in B. subtilis soil isolate MB9_B4 on certain media. We characterize the conditions where this pigment is produced and identify the corresponding BGC using a comparative genomic approach exploiting our strain collection containing other isolates with pigment production ability. The responsible BGC carried several genes, which were annotated as parts of the tryptophan biosynthesis pathway, possibly originating from a duplication and divergence of an originally primary metabolism. Identification of the pigment gene cluster additionally lead to the discovery of additional pigment BGC carrier B. subtilis isolates, some of which were described at the earliest in 1896 under the name Bacillus aterrimus, with a name referring to a dark pigmentation (the Latin "aterrimus" meaning very black). In addition, we employed solid-state nuclear magnetic resonance and Fourier transform infrared spectroscopies to characterize the chemical groups of the pigment. This study describes the chemical and biological features of a new class of SM BGC, which we hope will serve to improve the current BGC discovery pipelines in Bacilli.

microbiology↗

bioRxiv2024

Surfactin accelerates Bacillus subtilis pellicle biofilm development

Surfactin is a biosurfactant produced by many B. subtilis strains with a wide variety of functions from lowering surface tension to allowing motility of bacterial swarms, acting as a signaling molecule, and even exhibiting antimicrobial activities. However, the impact of surfactin during biofilm formation has been debated with variable findings between studies depending on the experimental conditions. B. subtilis is known to form biofilms at the solid-air, the solid-medium, and the liquid-air interfaces, the latter of which is known as a pellicle biofilm. Pellicle formation is a complex process requiring coordinated movement to the liquid-air interface and subsequent cooperative production of biofilm matrix components to allow robust pellicle biofilm formation. This makes pellicle formation a promising model system for assaying factors in biofilm formation and regulation. Here, we assayed the influence of surfactin and additional metabolites on the timing of pellicle biofilm formation. Using of time-lapse imaging, we assayed pellicle formation timing in 12 B. subtilis isolates and found that one, MB9_B4, was significantly delayed in pellicle formation by approximately 10 hours. MB9_B4 was previously noted to lack robust surfactin production. Indeed, deletion of surfactin synthesis in the other isolates delayed pellicle formation. Further, pellicle delay was rescued by addition of exogeneous surfactin and spent media from mature pellicles. Testing reporters of biofilm-related gene expression revealed that induction of pellicle formation was caused by a combination of increased gene expression of one of the biofilm components and promotion of growth. Intriguingly, spent media of surfactin mutant strains were also able to stimulate pellicle formation, indicating possible additional metabolites also influence the timing of pellicle development.

microbiology↗