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Organisationseinheit der BAM
Only a few myxobacteria are known to date that are classified as marine, owing to their salt dependency. In this study, the salt tolerance mechanism of these bacteria was investigated. To this end, a growth medium was designed in which the mutated Escherichia coli strain BKA13 served as sole food source for the predatory, heterotrophic myxobacteria. This enabled measurement of the osmolytes without any background and revealed that the closely related strains Enhygromyxa salina SWB007 and Plesiocystis pacifica SIR-1 developed different strategies to handle salt stress. Ple. pacifica SIR-1, which was grown between 1 and 4% NaCl, relies solely on the accumulation of amino acids, while Enh. salina SWB007, which was grown between 0.5 and 3% NaCl, employs, besides betaine, hydroxyectoine as the major compatible solute. In accordance with this analysis, only in the latter strain was a locus identified that codes for genes corresponding to the biosynthesis of betaine, ectoine and hydroxyectoine.
Only a few myxobacteria are known to date that are classified as marine, owing to their salt
dependency. In this study, the salt tolerance mechanism of these bacteria was investigated.
To this end, a growth medium was designed in which the mutated Escherichia coli strain
BKA13 served as sole food source for the predatory, heterotrophic myxobacteria. This enabled
measurement of the osmolytes without any background and revealed that the closely related
strains Enhygromyxa salina SWB007 and Plesiocystis pacifica SIR-1 developed different
strategies to handle salt stress. Ple. pacifica SIR-1, which was grown between 1 and 4% NaCl,
relies solely on the accumulation of amino acids, while Enh. salina SWB007, which was grown
between 0.5 and 3% NaCl, employs, besides betaine, hydroxyectoine as the major compatible
solute. In accordance with this analysis, only in the latter strain was a locus identified that codes
for genes corresponding to the biosynthesis of betaine, ectoine and hydroxyectoine.
Microbial communities in the immediate environment of socialized invertebrates can help to suppress pathogens, in part by synthesizing bioactive natural products. Here we characterized the core microbiomes of three termite species (genus Coptotermes) and their nest material to gain more insight into the diversity of termite-associated bacteria.
Sampling a healthy termite colony over time implicated a consolidated and highly stable microbiome, pointing toward the fact that beneficial bacterial phyla play a major role in termite fitness. In contrast, there was a significant shift in the composition of the core microbiome in one nest during a fungal infection, affecting the abundance of wellcharacterized Streptomyces species (phylum Actinobacteria) as well as less-studied bacterial phyla such as Acidobacteria. High-throughput cultivation in microplates was implemented to isolate and identify these less-studied bacterial phylogenetic group.
Amplicon sequencing confirmed that our method maintained the bacterial diversity of the environmental samples, enabling the isolation of novel Acidobacteriaceae and expanding the list of cultivated species to include two strains that may define new species within the genera Terracidiphilus and Acidobacterium.