Lovastatin-Enriched Rice Straw Enhances Biomass Quality and Suppresses Ruminal Methanogenesis

Abstract

The primary objective of this study was to test the hypothesis that solid state fermentation (SSF) of agro-biomass (using rice straw as model); besides, breaking down its lignocellulose content to improve its nutritive values also produces lovastatin which could be used to suppress methanogenesis in the rumen ecosystem. Fermented rice straw (FRS) containing lovastatin after fermentation withAspergillus terreuswas used as substrate for growth study of rumen microorganisms usingin vitrogas production method. In the first experiment, the extract from the FRS (FRSE) which contained lovastatin was evaluated for its efficacy for reduction in methane (CH4) production, microbial population, and activity in the rumen fluid. FRSE reduced total gas and CH4productions (P<0.01). It also reduced (P<0.01) total methanogens population and increased the cellulolytic bacteria includingRuminococcus albus,Fibrobacter succinogenes(P<0.01), andRuminococcus flavefaciens(P<0.05). Similarly, FRS reduced total gas and CH4productions, methanogens population, but increasedin vitrodry mater digestibility compared to the non-fermented rice straw. Lovastatin in the FRSE and the FRS significantly increased the expression of HMG-CoA reductase gene that produces HMG-CoA reductase, a key enzyme for cell membrane production in methanogenic Archaea.