Stenotrophomonas-Like Bacteria Are Widespread Symbionts in Cone Snail Venom Ducts

Abstract

Cone snails are biomedically important sources of peptide drugs, but it is not known whether snail-associated bacteria affect venom chemistry. To begin to answer this question, we performed 16S rRNA gene amplicon sequencing of eight cone snail species, comparing their microbiomes with each other and with those from a variety of other marine invertebrates. We show that the cone snail microbiome is distinct from those in other marine invertebrates and conserved in specimens from around the world, including the Philippines, Guam, California, and Florida. We found that all venom ducts examined contain diverse 16S rRNA gene sequences bearing closest similarity to bacteria. These sequences represent specific symbionts that live in the lumen of the venom duct, where bioactive venom peptides are synthesized. In animals, symbiotic bacteria contribute critically to metabolism. Cone snails are renowned for the production of venoms that are used as medicines and as probes for biological study. In principle, symbiotic bacterial metabolism could either degrade or synthesize active venom components, and previous publications show that bacteria do indeed contribute small molecules to some venoms. Therefore, understanding symbiosis in cone snails will contribute to further drug discovery efforts. Here, we describe an unexpected, specific symbiosis between bacteria and cone snails from around the world.

Combining microfluidics and RNA-sequencing to assess the inducible defensome of a mushroom against nematodes

“…These findings suggested the possibility of the involvement of nematode-associated bacteria in fungal-nematode interactions. The importance of the bacterial community of nematodes for the fitness and virulence of parasites was previously suggested in several studies [44, 45, 47, 48, 51]. Although there are several studies that have analysed the bacteria associated with bacterivorous [41, 42], plant pathogenic [44, 49, 50, 52], and animal parasitic [43] nematodes, currently no data concerning the bacterial communities associated with fungivorous nematodes is available.…”

Highly Reproducible 16S Sequencing Facilitates Measurement of Host Genetic Influences on the Stickleback Gut Microbiome

“…Although quantification of the microbiome may now be achieved using shotgun metagenomic approaches (2), for instance to measure disease-microbiome associations (3), marker-based techniques such as high-throughput 16S rRNA amplicon sequencing are still the most cost-effective, straightforward, and commonly applied methods for microbial community profiling. However, as researchers extend their work beyond routinely characterized environments such as soil and human fecal samples and into new, diverse study systems (4–6), the adoption and extension of previously optimized techniques should occur cautiously and intentionally. Methodologies for 16S amplicon sequencing should ideally be evaluated at multiple stages (i.e., sample collection and handling through analysis), compared with multiple alternative options, and evaluated with respect to the discriminatory power and precision of diversity analyses based on them.…”

Microbial adaptation to venom is common in snakes and spiders

“…Accordingly, in an experimental rabbit model of dermonecrosis (Monteiro et al 2002) caused by Loxosceles intermedia (recluse spider) venom, Clostridium perfringens recovered from the spider fang and venom enhanced disease symptoms. Stenotrophomonas-like bacteria were also found to dominate cone snail venom microbiomes (Torres et al 2017),…”

“…Stenotrophomonas-like bacteria were also found to dominate cone snail venom microbiomes (52), indicating that microbial venom adaptation may extend well beyond snakes, spiders, scorpions, and snails. The cone snail study also reported comparable microbiomes in samples collected across the Pacific basin as well as Atlantic specimens.…”