Multiple cellobiohydrolases and cellobiose phosphorylases cooperate in the ruminal bacterium Ruminococcus albus 8 to degrade cellooligosaccharides

Abstract

Digestion of plant cell wall polysaccharides is important in energy capture in the gastrointestinal tract of many herbivorous and omnivorous mammals, including humans and ruminants. The members of the genus Ruminococcus are found in both the ruminant and human gastrointestinal tract, where they show versatility in degrading both hemicellulose and cellulose. The available genome sequence of Ruminococcus albus 8, a common inhabitant of the cow rumen, alludes to a bacterium well-endowed with genes that target degradation of various plant cell wall components. The mechanisms by which R. albus 8 employs to degrade these recalcitrant materials are, however, not clearly understood. In this report, we demonstrate that R. albus 8 elaborates multiple cellobiohydrolases with multi-modular architectures that overall enhance the catalytic activity and versatility of the enzymes. Furthermore, our analyses show that two cellobiose phosphorylases encoded by R. albus 8 can function synergistically with a cognate cellobiohydrolase and endoglucanase to completely release, from a cellulosic substrate, glucose which can then be fermented by the bacterium for production of energy and cellular building blocks. We further use transcriptomic analysis to confirm the over-expression of the biochemically characterized enzymes during growth of the bacterium on cellulosic substrates compared to cellobiose.

Transcriptomic analysis of stress response to novel antimicrobial coatings in a clinical MRSA strain

“…Cellulose is a linear chain of β-1, 4-glucose monomers linked by β-1, 4-glycosidic bonds [42,43]. Bacteria degrade it using three types of enzymes: endoglucanases and cellobiohydrolases, which synergistically depolymerize cellulose to cellobiose, followed by β-glucosidases, which hydrolyse cellobiose to glucose [42,44,45].…”

“…Cellulose is a linear chain of β-1, 4-glucose monomers linked by β-1, 4-glycosidic bonds [42,43]. Bacteria degrade it using three types of enzymes: endoglucanases and cellobiohydrolases, which synergistically depolymerize cellulose to cellobiose, followed by β-glucosidases, which hydrolyse cellobiose to glucose [42,44,45]. The action of the β-glucosidases is the rate-limiting factor in cellulose degradation, making the study of the expression of these genes imperative to understand cellulose degradation [44].…”

Comparative contribution of substrate structure and microbial composition to volatile fatty acid production in the fermentation of corn stover

“…Besides, the composition of the rumen microorganisms may also have a certain effect on cellulase activity. The enzymes secreted by different microorganisms may have synergistic promoting effects and inhibiting effects on exogenous cellulase [32]. Therefore, it is necessary to analyze the product compositions and the internal reasons further.…”

Gut Microbiome Analysis of Snails: A Biotechnological Approach

“…The guts of herbivores that largely feed on lignocellulosic rich plant materials act as natural bioreactors for the degradation of plant biomass making them efficient sources of industrially important bacteria [59]. In many herbivores and omnivores, the digestion of the plant biomass is of immense importance for the energy capture [60]. Therefore, bacterial flora present in the GI tract of these animals may have an important role in digestion.…”

“…Some of the microbes such as bacteria Fibrobacter succinogenes, R. flavefaciens and R. albus [95] and some fungi are primarily responsible for degradation of plant cell walls. R. albus8 is anaerobic, fibrolytic and gram-positive bacterium present in herbivores and can degrade both cellulose and hemicellulose [60,96]. But R. flavefaciens and R. champanellensis are very efficient cellulose degraders due to their cellulosome secretion which is lacking in case of R. albus8 [97].…”