Use of Lactic Acid Bacteria to Reduce Methane Production in Ruminants, a Critical Review.

Natasha Doyle,R Paul Ross,Yang Li,Graeme Attwood,William J Kelly,Catherine Stanton,Sinead Leahy,Philiswa Mbandlwa

doi:10.3389/fmicb.2019.02207

Abstract

Enteric fermentation in ruminants is the single largest anthropogenic source of agricultural methane and has a significant role in global warming. Consequently, innovative solutions to reduce methane emissions from livestock farming are required to ensure future sustainable food production. One possible approach is the use of lactic acid bacteria (LAB), Gram positive bacteria that produce lactic acid as a major end product of carbohydrate fermentation. LAB are natural inhabitants of the intestinal tract of mammals and are among the most important groups of microorganisms used in food fermentations. LAB can be readily isolated from ruminant animals and are currently used on-farm as direct-fed microbials (DFMs) and as silage inoculants. While it has been proposed that LAB can be used to reduce methane production in ruminant livestock, so far research has been limited, and convincing animal data to support the concept are lacking. This review has critically evaluated the current literature and provided a comprehensive analysis and summary of the potential use and mechanisms of LAB as a methane mitigation strategy. It is clear that although there are some promising results, more research is needed to identify whether the use of LAB can be an effective methane mitigation option for ruminant livestock.

Highlights

While ruminant animals play an important role in sustainable agricultural systems (Eisler et al, 2014) they are an important source of greenhouse gas (GHG) emissions (Reisinger and Clark, 2018)
lactic acid bacteria (LAB) have long been used as starter cultures for a wide range of dairy, meat and plant fermentations, and this history of use in human and animal foods has resulted in most LAB having Qualified Presumption of Safety (QPS) status in the European Union or Generally Recognized as Safe (GRAS) status in the United States
The effect is clearly strain dependent and it is not understood whether the LAB or their metabolites affect the methanogens themselves, or whether they affect the other rumen microbes that produce substrates necessary for methanogenesis

Summary

Introduction

While ruminant animals play an important role in sustainable agricultural systems (Eisler et al, 2014) they are an important source of greenhouse gas (GHG) emissions (Reisinger and Clark, 2018). There is limited research available on the efficacy of LAB DFMs. Their use is targeted at improving the health and performance of animals (Table 2). If LAB can be found to reduce ruminant CH4 production effectively both DFMs and inoculants provide a practical and useful mitigation option on-farm.

Results

Conclusion