A sequencing approach targeting the 16S rRNA gene unravels the biofilm composition of spiral-wound membranes used in the dairy industry

Abstract

Few data are available concerning the composition of biofilms found at the surface of filtration membranes, which, to some extent, explains the long-term failure of numerous strategies developed to control biofouling. This preliminary study intended to design a metagenomic tool targeting the 16S rRNA gene in order to unravel a general portrait of bacterial communities found on spiral-wound membranes used in the dairy industry. A total of seven spiral-wound membrane elements (ultrafiltration, nanofiltration, or reverse osmosis) at the end of their useful lifetimes were collected from different dairy plants. Targeted analysis of the 16S rRNA genes of the metagenome extracted from the membranes revealed their bacterial diversity via high-throughput sequencing technology (Miseq, Illumina). It was found that the nature of the filtered fluid (milk, whey, water) explained 58.6 % of the variance observed between communities found on membranes. Treatments applied on dairy fluids (milk pasteurization, whey bleaching or whey ultrafiltration) induced a selective pressure that affected the diversity of bacterial communities found on membranes and the proportions of spore-former bacteria among them. This work provides the first complete bacterial portrait of the biofilm composition of spiral-wound membranes used in the dairy industry. It suggests that the nature of the filtered fluid and potentially filtration operating parameters may be important elements to consider in order to design new cleaning strategies or preventive measures targeting biofouling.