Effects of LCFA on the Gas Production, Cellulose Digestion and Cellulase Activities by the Rumen Anaerobic Fungus, Neocallimastix frontalis RE1

Methane production and estimation from livestock husbandry: A mechanistic understanding and emerging mitigation options

Globally, livestock is an important contributor to methane (CH₄) emissions. This paper reviewed the various CH₄ measurement and estimation techniques and mitigation approaches for the livestock sector. Two approaches for enteric livestock CH₄ emission estimation are the top-down and bottom-up. The combination of both could further improve our understanding of enteric CH₄ emission and possible mitigation measures. We discuss three mitigation approaches: reducing emissions, avoiding emissions, and enhancing the removal of emissions from livestock. Dietary management, livestock management, and breeding management are viable reducing emissions pathways. Dietary manipulation is easily applicable and can bring an immediate response. Economic incentive policies can help the livestock farmers to opt for diet, breeding, and livestock management mitigation approaches. Carbon pricing creates a better option to achieve reduction targets in a given period. A combination of carbon pricing, feeding management, breeding management, and livestock management is more feasible and sustainable CH₄ emissions mitigation strategy rather than a single approach.

Effects of emulsified octadecanic acids on gas production and cellulolysis by the rumen anaerobic fungus, Piromyces communis M014

Responses of the rumen anaerobic fungus, Piromyces communis M014, to octadecanic long-chain fatty acids (LCFAs) were evaluated by measuring total and hydrogen gas productions, filter paper (FP) cellulose degradation and polysaccharidase enzyme activities. Octadecanic acids (stearic acid, C(18:0); oleic acid, C(18:1); linoleic acid, C(18:2) and linolenic acid, C(18:3)) were emulsified by ultrasonication under anaerobic conditions, and added to the medium at the level of 0.001%. When P. communis M014 was grown in culture with stearic and oleic acids, the cumulative gas production, FP cellulose digestion and enzyme activities were significantly (p<0.05) increased in the early incubation times relative to those for the control. However, the addition of linolenic acid inhibited all of the investigated parameters, including cellulose degradation, enzyme activities and gas production, up to 168h incubation. These results indicated that stearic and oleic acids tended to have stimulatory effects on fungal cellulolysis, whereas linolenic acid caused a significant (p<0.05) inhibitory effect on cellulolysis by the rumen fungus. The fungus, P. communis M014, can biohydrogenate C(18) unsaturated fatty acids to escape from their toxic effects. Therefore, in this study, the results indicated that the more highly the added C(18) LCFA to the fungal culture was unsaturated, the higher the inhibition of gas production and cellulase enzyme activity was.