The cellulolytic microflora of the human colon: evidence of microcrystalline cellulose-degrading bacteria in methane-excreting subjects

Abstract

In humans, plant cell wall polysaccharides (mainly cellulose and hemicelluloses) represent an important source of dietary fibres that are digested by the gut microflora. However, the fibrolytic micro-organisms involved in the breakdown of these substrates remain largely unknown. Our objective was to quantify the microcrystalline-cellulose-degrading and methanogenic microbial communities in faecal samples (n=34) from both methane- and non-methane-excreting individuals and to identify the predominant cellulolytic organisms in these two categories of subjects. Microcrystalline cellulose degraders could only be enumerated in faecal samples from methane excretors while this community remained undetectable in non-methane-excretors. The cellulolytic isolates corresponded to new Ruminococcus species and to Enterococcus sp. closely related to Enterococcus faecalis. The presence of such fibrolytic species seems to be linked to that of methanogenic archaea in the gut, the relationships between these two microbial communities needing further investigation. Our findings suggest that the structure and activity of the cellulolytic communities differ in methane- and non-methane-excreting individuals.

Ruminococcus champanellensis sp. nov., a cellulose-degrading bacterium from human gut microbiota

“…However, the presence of cellulolytic Ruminococcus-like strains in the human Strain 18P13 T was isolated from a fresh faecal sample of a 38-year-old methane-excreting healthy human female who had not received antibiotics in the last 3 months, had no diagnosed gastrointestinal disease, consumed a diverse Western diet that included at least 15 g dietary fibre per day and had a normal body mass index (18-25 kg m 22 ). The isolation procedure has been described previously (Robert & Bernalier-Donadille, 2003). Briefly, faecal dilutions were inoculated into liquid basal cellulolytic (BC) medium containing 100 mg Whatman no.…”

“…Ruminococcus bromii and Ruminococcus callidus, isolated from the human gut, are able to degrade other complex polysaccharides such as starch or xylan (Leitch et al, 2007). However, the presence of cellulolytic Ruminococcus-like strains in the human gut was reported by Robert & Bernalier-Donadille (2003). More recently, a real-time PCR analysis was developed to quantify cellulose-degrading ruminococci in human faeces and used to confirm their presence in the human gut, especially in methane-excreting individuals (Chassard et al, 2010).…”

“…During an investigation of the cellulose-degrading community of the human gut, we isolated five cellulolytic, Gram-positive, anaerobic cocci from two healthy human faecal samples (Robert & Bernalier-Donadille, 2003). The isolates were assigned to the genus Ruminococcus on the basis of 16S rRNA gene sequence analysis, their closest relatives being R. flavefaciens ATCC 19208 T and R. callidus ATCC 27760 T .…”

“…The isolation procedure has been described previously (Robert & Bernalier-Donadille, 2003). Briefly, faecal dilutions were inoculated into liquid basal cellulolytic (BC) medium containing 100 mg Whatman no.…”

Advancement in Packaging Film Using Microcrystalline Cellulose and TiO<sub>2</sub>

“…This increases microbial attack, which produces defects in mechanical behavior. Therefore biodegradation occurs when microorganisms consume microcrystalline cellulose, leading to increased porosity and voidness and decreased structural integrity of the matrix [12,13,14]. The percent weight loss increased with increase in cellulose content in LLDPE system.…”