Transcriptomic and phenomic investigations reveal elements in biofilm repression and formation in the cyanobacteriumSynechococcus elongatusPCC 7942

Abstract

Biofilm formation by photosynthetic organisms is a complex behavior that serves multiple functions in the environment. Biofilm formation in the unicellular cyanobacterium Synechococcus elongatus PCC 7942 is regulated in part by a set of small secreted proteins that promotes biofilm formation and a self-suppression mechanism that prevents their expression. Little is known about the regulatory and structural components of the biofilms in PCC 7942, or response to the suppressor signal(s). We performed transcriptomics (RNA-Seq) and phenomics (RB-TnSeq) screens that identified four genes involved in biofilm formation and regulation, more than 25 additional candidates that may impact biofilm formation, and revealed the transcriptomic adaptation to the biofilm state. In so doing, we compared the effectiveness of these two approaches for gene discovery.

Impairment of a cyanobacterial glycosyltransferase that modifies a pilin results in biofilm development

“…A genetic screen using a barcoded transposon library suggested that inactivation of gene Synpcc7942_0051 causes biofilm development (Simkovsky et al, 2022). Briefly, this S. elongatus library of mutants was grown, a biofilm was allowed to form, and DNA extracted from the biofilm was analysed by high-throughput sequencing.…”

“…A genetic screen using a barcoded transposon library suggested that inactivation of gene Synpcc7942_0051 causes biofilm development (Simkovsky et al ., 2022 ). Briefly, this S .…”

“…Enrichment of a mutant in the sessile subpopulation of the library implies that the particular strain is capable of biofilm development; however, it is possible that the mutant merely intercalated into and proliferated within a biofilm formed by other mutants in the library. Therefore, we constructed individual mutants and examined their ability to develop biofilms in a pure culture (Simkovsky et al ., 2022 ). One of the mutants enriched in the biofilm is impaired in a gene encoding a glycosyltransferase homologue, O‐linked β‐N‐acetylglucosamine (O‐GlcNAc) transferase (Ogt).…”

“…To identify additional components of the biofilm self‐suppression mechanism of S . elongatus , a high‐throughput screen using a barcoded transposon library was employed (Simkovsky et al ., 2022 ). This screen suggested involvement of several genes, including Synpcc7942_0051, in biofilm inhibition.…”