An untapped bacterial cellulolytic community enriched from coastal marine sediment under anaerobic and thermophilic conditions.

A bacterial community with strong cellulose [filter paper (FP) and microcrystalline cellulose] degradation ability was isolated from the coastal marine environment. They were isolated under thermophilic (60 °C) and anaerobic cultivation conditions. The library of 16S rRNA gene clones revealed a total of 16 operational taxonomic units after 50 clones were surveyed. Sixty percent of the clones were most related to the type strain of Clostridium thermocellum with 16S rRNA gene identity around 87-89%. All of them showed extremely low sequence similarities and were novel at least in species level. The gene clone libraries of glycosyl hydrolase family 48 showed low gene and amino acid sequence similarities around 70-72%. The results indicated that the cellulose degradation systems in the specific environment have not been well studied. The enrichment could disrupt FP within 3 days in a basal medium. The cellulase activity of the community was comparable to that of C. thermocellum LQR1. The main fermentation products were ethanol, acetic acid and butyric acid. This work identified a novel microbial resource with a potential in lignocellulose conversion and biofuel production.