Developing co-cultures of bacterial isolates from the bryozoan Cristatella mucedo for the discovery of novel secondary metabolites

Abstract

In nature, bacteria usually exist as part of diverse microbial communities where different types of interactions occur. The study of well-defined microbial interactions and their metabolic activities has led to the discovery of new bioactive secondary metabolites¹. Advances in bacterial genomics, metagenomics, and the study of secondary metabolite biosynthesis pathways revealed the potential of certain species to produce compounds that could never be produced in the laboratory-based cultivation of single isolates. Genes that encode biosynthetic pathways for the synthesis of secondary metabolites (BGCs), are localized in specialized regions of the bacterial genomes. Most of these BGCs are “silent” under laboratory conditions and the environmental signals triggering their expression remain largely unknown. Recent studies demonstrate that co-cultivation of bacteria stimulates the production of novel secondary metabolites never before detected in monocultures². In this study, we explore the biosynthetic potential of the microbiota from a fresh-water bryozoan Cristatella mucedo. In particular, we focus on isolation and co-cultivation of bacteria other than well-studied Streptomyces species. For this purpose, representatives of 28 bacteria genera have been isolated, taxonomically classified and genome sequenced. The selection of isolates with highest number of unique BGCs and hence capacity to produce secondary metabolites was performed using antiSMASH software³. Liquid co-cultivation with Bacillus sp. and Rhodococcus sp. isolates followed by HPLC, and LC-MS analyses revealed the induction and upregulation of several compounds, including a potential new natural product.