Isolation, characterization and strain selection of a Paenibacillus species for use as a probiotic to aid in ruminal methane mitigation, nitrate/nitrite detoxification and food safety

Authors: LATHAM, ELIZABETH - Texas A&M University; PINCHAK, WILLIAM - Texas A&M Agrilife; TRACHSEL, JULIAN - Iowa State University; Allen, Heather; Callaway, Todd; Nisbet, David; Anderson, Robin

Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2018
Publication Date: 4/30/2018
Publication URL: http://handle.nal.usda.gov/10113/6472381
Citation: Latham, E.A., Pinchak, W.E., Trachsel, J., Allen, H.K., Callaway, T.R., Nisbet, D.J., Anderson, R.C. 2018. Isolation, characterization and strain selection of a Paenibacillus species for use as a probiotic to aid in ruminal methane mitigation, nitrate/nitrite detoxification and food safety. Bioresource Technology. 263:358-364. https://doi.org/10.1016/j.biortech.2018.04.116.
DOI: https://doi.org/10.1016/j.biortech.2018.04.116

Interpretive Summary: Cattle, sheep, and goats are important food producing animals that have a unique gastrointestinal system that is made up of a large paunch, called the rumen, located in front of the true stomach and small and large intestines. The rumen of these animals is filled with diverse populations of microorganisms that digest feedstuffs such as grass, weeds, and straw that humans and simpler stomached animals such as pigs and chickens cannot digest. This enables cows, sheep, and goats to convert feedstuffs unusable by humans into high quality meat and milk for the betterment of humankind. Despite the good works accomplished by the beneficial microbes in the rumen of cattle, sheep, and goats, there are also some undesirable microbes that can inhabit this environment, including pathogens that can make the animal sick as well as people if they make their way into the food we eat. Additionally, there are some bacteria in the rumen that make the animal less efficient in digesting the food they eat, such as bacteria that make methane, which can cause the animal to lose as much as 12% of the dietary energy available in their food. In this study, we isolated from the rumen of a cow a bacterium that has never before been described and found that when grown with certain foodstuffs, this bacterium can help reduce methane production and reduce numbers of undesired pathogenic bacteria such as E. coli and Campylobacter in the rumen environment by more than 100-fold. We have further found that this bacterium can degrade nitrate and nitrite which are toxic chemicals that oftentimes accumulate to high levels in heat- or drought-stressed forages. The results from this research may ultimately provide farmers and ranchers with a new tool to more efficiently produce microbiologically safer meat and milk at less cost to the American consumer and less impact on the environment.

Technical Abstract: The effects of dietary nitrate and Paenibacillus 79R4 (79R4), a denitrifying bacterium co-administered as a probiotic, on methane emissions, nitrate and nitrite-metabolizing capacity, and fermentation characteristics were studied in vitro. Mixed populations of rumen microbes inoculated with 79R4 metabolized all levels of nitrite studied after 24 h in vitro incubation. Results from in vitro simulations resulted in up to 2 log10 colony forming unit reductions in E. coli O157:H7 and Campylobacter jejuni when these were co-cultured with 79R4. Nitrogen gas was the predominant final product of nitrite reduction by 79R4. When tested with nitrate-treated incubations of rumen microbes, 79R4 inoculation (provided to achieve 106 cells/mL rumen fluid volume) complemented the ruminal methane-decreasing potential of nitrate (P < 0.05) while concurrently increasing ruminal nitrate and nitrite-metabolizing activity (P < 0.05) compared to untreated and nitrate only-treated incubations.