Isolation and characterization of mimosine, 3, 4 DHP and 2, 3 DHP degrading bacteria from a commercial rumen inoculum

Abstract

The presence of the toxic amino acid mimosine in Leucaena leucocephala restricts its use as a protein source for ruminants. Rumen bacteria degrade mimosine to 3,4- and 2,3-dihydroxypyridine (DHP), which remain toxic. Synergistes jonesii is believed to be the main bacterium responsible for degradation of these toxic compounds but other bacteria may also be involved. In this study, a commercial inoculum provided by the Queensland's Department of Agriculture, Fisheries, and Forestry was screened for isolation and characterization of mimosine, 3,4- and 2,3-DHP degrading bacterial strains. A new medium for screening of 2,3-DHP degrading bacteria was developed. Molecular and biochemical approaches used in this study revealed four bacterial isolates - Streptococcus lutetiensis, Clostridium butyricum, Lactobacillus vitulinus, and Butyrivibrio fibrisolvens - to be able to completely degrade mimosine within 7 days of incubation. It was also observed that C. butyricum and L. vitulinus were able to partially degrade 2,3-DHP within 12 days of incubation, while S. lutetiensis, was able to fully degrade both 3,4 and 2,3 DHP. Collectively, we concluded that S. jonesii is not the sole bacterium responsible for detoxification of Leucaena. Comprehensive screening of rumen fluid of cattle grazing on Leucaena pastures is needed to identify additional mimosine-detoxifying bacteria and contribute to development of more effective inoculums to be used by farmers against Leucaena toxicity.

Toxin Degradation by Rumen Microorganisms: A Review

“…Non-protein amino acids can be incorporated into protein chains leading to the formation of non-functional products that cannot be metabolised [ 98 ]. The presence of non-protein amino acids in fodder poses risks to livestock due to their potential toxicity and anti-nutritional properties [ 25 , 64 , 99 ]. There are ca.…”

“…Based on early studies, it was thought that mimosine detoxification would require synergism between a variety of rumen microorganisms, with Jones and Megarrity [ 15 ] demonstrating that there were a range of bacteria in the rumen able to degrade mimosine to 3,4-DHP. A number of bacteria have been isolated including Streptococcus lutetiensis , Clostridium butyricum , Lactobacillus vitulinus and Butyrivibrio fibrisolvens that are able to degrade mimosine to DHP [ 99 ]. Additional bacteria such as S. jonesii are required for the further breakdown of 3,4-DHP to 2,3-DHP which S. jonesii can further convert to unidentified non-toxic metabolites.…”

Plant secondary metabolites induced electron flux in microbial fuel cell: investigation from laboratory-to-field scale

“… 23 – 25 and Eucalyptus extract has terpenes, acylphloroglucinols, euglobals, etc. 26 and mimosine presence in case of Leucaena 27 . The control MFC-C achieved a steady-state after 40 days of operation, depicting a stable OV value of 292 ± 5 mV.…”

Faecal inoculations alter the gastrointestinal microbiome and allow dietary expansion in a wild specialist herbivore, the koala

“…In other study systems, the GI microbiome has been directly shown to influence diet selection through a single identifiable secondary metabolite or toxin that can be broken down by known microbial species that inhabits an enlarged foregut. For instance, Australian cattle eat Leucaena leucocephala only when bacteria that degrade mimosine are introduced to the rumen [7,48]. Furthermore, when the foregut pouches of woodrats (Neotoma spp.)…”