Effects of alkaline hydrogen peroxide treatment on in vitro degradation of cellulosic substrates by mixed ruminal microorganisms and Bacteroides succinogenes S85.

Abstract

The effects of sodium hydroxide (NaOH) and alkaline hydrogen peroxide (AHP) treatments on wheat straw (WS) and various cellulosic substrates were determined by measuring susceptibility to degradation by mixed ruminal organisms or Bacteroides succinogenes S85. In vitro incubations were used to measure differences in fermentation resulting from each successive step in the AHP treatment process. In vitro incubations through 48 or 108 h were conducted to measure these differences. The AHP treatment of WS increased (P less than 0.05) dry matter, neutral detergent fiber, and acid detergent fiber degradation over control WS when these substrates were incubated with mixed ruminal microorganisms or B. succinogenes S85. Fermentations containing AHP-treated WS had greater (P less than 0.05) microbial purine (RNA) and volatile fatty acid concentrations by 12 h compared with those containing untreated or NaOH-treated WS. Xylose in AHP-treated WS was utilized more extensively (P less than 0.05) by 12 h compared with the xylose of untreated or NaOH-treated WS. Treatment with AHP removed 23% of the alkali-labile phenolic compounds from WS. When substrates with high levels of crystalline cellulose (raw cotton fiber, Solka floc, and Sigmacell-50) were treated with NaOH or AHP and incubated for 108 h with B. succinogenes S85, extent of acid detergent fiber degradation of cotton fiber and Sigmacell-50 was similar to that of their respective controls. Sodium hydroxide and AHP treatments were effective in increasing acid detergent fiber degradation of the Solka floc which contained, on average, 3.3 and 4.8 percentage units more acid detergent lignin and hemicellulose, respectively, than cotton fiber and Sigmacell-50.(ABSTRACT TRUNCATED AT 250 WORDS)