Evaluating Distribution of Bacterial Natural Product Biosynthetic Gene Clusters Across Lake Huron Sediment

Environmental microorganisms continue to serve as a major source of bioactive natural products (NPs) and as an inspiration for many other scaffolds in the toolbox of modern medicine. Nearly all microbial NP-inspired therapies can be traced to field expeditions to collect samples from the environment. Despite the importance of these expeditions towards the search for new drugs, few studies have attempted to document the extent to which NPs or their corresponding production genes are distributed within a given environment. To gain insight into this, the geographic occurrence of NP ketosynthase (KS) and adenylation (A) domains was documented across 53 and 58 surface sediment samples, respectively, covering a 59,590 square kilometer of Lake Huron. Overall, no discernable patterns in NP distribution were observed when comparing operational biosynthetic units (OBUs) from an estimated 91,721 NP classes consisting of nonribosomal peptides and polyketides. We observed that the distribution profiles of the majority of A domain OBUs were non-overlapping across the 58 locations, while each location harbored relatively equal number of OBUs, suggesting that at the sequencing depth used in this study, no single location served as a NP ?hotspot?. This preliminary evidence supports that there is ample variation in NP occurrence between sampling sites and suggests that extensive sample collection efforts may be required to fully capture the diversity that exists in sediment on a regional scale.