Comparative analysis of functional diversity of rumen microbiome in bison and beef heifers

IMPORTANCE

Ruminants play a key role in the conversion of cellulolytic plant material into high-quality meat and milk protein for humans. The rumen microbiome is the driver of this conversion, yet there is little information on how gene expression within the microbiome impacts the efficiency of this conversion process. The current study investigates gene expression in the rumen microbiome of beef heifers and bison and how transplantation of ruminal contents from bison to heifers alters gene expression. Understanding interactions between the host and the rumen microbiome is the key to developing informed approaches to rumen programming that will enhance production efficiency in ruminants.

Role of Transglycosylation Products in the Expression of Multiple Xylanases in Myceliophthora sp. IMI 387099

This study reports the regulation of multiple xylanases produced by Myceliophthora sp. IMI 387099. Fructose was found to positively regulate the expression of multiple xylanase when used as sole carbon source. The xylanases (EX(1 )and EX(2)) of acidic pI were expressed in the presence of simple sugars (glucose, arabinose, and xylose), whereas xylanase of both acidic as well as basic pI (EX(1,) EX(2,) EX(3), and EX(5)) were expressed in the presence of fructose, xylan, and combination of xylan and alcohol. The combination of fructose and xylan also led to expression of an additional xylanase (EX(4)). The positional isomer (iso-X4) was found to be the key transglycosylation product when cultures were grown in the presence of fructose and xylan. In the presence of alcohols, the higher expression of xylanase was ascribed to the synergistic effect of alkyl glycoside and other transglycosylation products present in the culture extracts.

Production of multiple xylanolytic and cellulolytic enzymes by thermophilic fungus Myceliophthora sp. IMI 387099

This study reports the production of xylanolytic and cellulolytic enzymes by a thermophilic fungal isolate Myceliophthora sp. using a cheap medium containing rice straw and chemically defined basal medium under solid-state culture. A combination of one factor at a time approach followed by response surface methodology using Box-Behnken design of experiments resulted in 2.5, 1.25, 1.28 and 4.23 fold increase in xylanase, endoglucanase, beta-glucosidase and FPase activity, respectively. The zymograms developed against IEF gels showed that multiple isoforms of xylanase (5), endoglucanase (4) and beta-glucosidase (2) were produced under optimized culture conditions. Moreover, thiol containing serine proteases produced during the growth of the culture had no role in the post-translational modification of these xylanases.