Genetically Modified Ruminal Bacteria Protect Sheep from Fluoroacetate Poisoning

Gregg, Keith; Hamdorf, Brenton; Henderson, Kerrin; Kopečný, J.; Wong, Cheryl M.

doi:10.1128/aem.64.9.3496-3498.1998

Cited by 97 publications

(48 citation statements)

References 9 publications

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“…Globally, fluoroacetate is found in over 40 plant species (Baron et al, 1987;Harper et al, 2003) and is responsible for the intoxication of commercial livestock species (Aplin & Cannon, 1971;Nwude & Parsons, 1977;McIlroy, 1982). Owing to this problem associated with fluoroacetate-accumulating plants, dehalogenase genes have also FEMS Microbiol Ecol 80 (2012) 671-684 ª 2012 Commonwealth of Australia MICROBIOLOGY ECOLOGY been used to develop transgenic rumen bacteria (Gregg et al, 1994) which detoxify fluoroacetate within the gastrointestinal tract of ruminant livestock (Gregg et al, 1998;Padmanabha et al, 2004). The use of dehalogenases and other microbial enzymes has also been proposed for bioremediation of contaminated soil and water (Loffler & Edwards, 2006).…”

Section: Introductionmentioning

confidence: 99%

Isolation and survey of novel fluoroacetate-degrading bacteria belonging to the phylum Synergistetes

Davis

Webb

Sly

et al. 2012

FEMS Microbiol Ecol

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Microbial dehalogenation of chlorinated compounds in anaerobic environments is well known, but the degradation of fluorinated compounds under similar conditions has rarely been described. Here, we report on the isolation of a bovine rumen bacterium that metabolizes fluoroacetate under anaerobic conditions, the mode of degradation and its presence in gut ecosystems. The bacterium was identified using 16S rRNA gene sequence analysis as belonging to the phylum Synergistetes and was designated strain MFA1. Growth was stimulated by amino acids with greater quantities of amino acids metabolized in the presence of fluoroacetate, but sugars were not fermented. Acetate, formate, propionate, isobutryate, isovalerate, ornithine and H2 were end products of amino acid metabolism. Acetate was the primary end product of fluoroacetate dehalogenation, and the amount produced correlated with the stoichiometric release of fluoride which was confirmed using fluorine nuclear magnetic resonance (19F NMR) spectroscopy. Hydrogen and formate produced in situ were consumed during dehalogenation. The growth characteristics of strain MFA1 indicated that the bacterium may gain energy via reductive dehalogenation. This is the first study to identify a bacterium that can anaerobically dehalogenate fluoroacetate. Nested 16S rRNA gene‐specific PCR assays detected the bacterium at low numbers in the gut of several herbivore species.

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Section: Introductionmentioning

confidence: 99%

Isolation and survey of novel fluoroacetate-degrading bacteria belonging to the phylum Synergistetes

Davis

Webb

Sly

et al. 2012

FEMS Microbiol Ecol

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“…Similarly, mono£uoroacetate is found in various pasture plants at levels of up to 5 g kg 31 [194] and has an LD 50 in ruminants of approximately 0.3 mg kg 31 of body weight. Gregg et al [143] inoculated four strains of recombinant B. ¢brisolvens, transformed with a gene encoding £uoroacetate dehalogenase into sheep.…”

Section: Introductionmentioning

confidence: 99%

Opportunities to improve fiber degradation in the rumen: microbiology, ecology, and genomics

et al. 2003

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The degradation of plant cell walls by ruminants is of major economic importance in the developed as well as developing world. Rumen fermentation is unique in that efficient plant cell wall degradation relies on the cooperation between microorganisms that produce fibrolytic enzymes and the host animal that provides an anaerobic fermentation chamber. Increasing the efficiency with which the rumen microbiota degrades fiber has been the subject of extensive research for at least the last 100 years. Fiber digestion in the rumen is not optimal, as is supported by the fact that fiber recovered from feces is fermentable. This view is confirmed by the knowledge that mechanical and chemical pretreatments improve fiber degradation, as well as more recent research, which has demonstrated increased fiber digestion by rumen microorganisms when plant lignin composition is modified by genetic manipulation. Rumen microbiologists have sought to improve fiber digestion by genetic and ecological manipulation of rumen fermentation. This has been difficult and a number of constraints have limited progress, including: (a) a lack of reliable transformation systems for major fibrolytic rumen bacteria, (b) a poor understanding of ecological factors that govern persistence of fibrolytic bacteria and fungi in the rumen, (c) a poor understanding of which glycolyl hydrolases need to be manipulated, and (d) a lack of knowledge of the functional genomic framework within which fiber degradation operates. In this review the major fibrolytic organisms are briefly discussed. A more extensive discussion of the enzymes involved in fiber degradation is included. We also discuss the use of plant genetic manipulation, application of free-living lignolytic fungi and the use of exogenous enzymes. Lastly, we will discuss how newer technologies such as genomic and metagenomic approaches can be used to improve our knowledge of the functional genomic framework of plant cell wall degradation in the rumen.

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“…Several investigators have released bacteria into the rumen and have generally found that organisms disappeared within a few hours (Attwood et al 1988;Miyagi et al 1996;Gregg et al 1998). In contrast, it was possible here to detect xynA in the rumen for more than 20 days with highly speci®c PCR primers.…”

Section: Discussionmentioning

confidence: 80%

Expression of a modified Neocallimastix patriciarum xylanase in Butyrivibrio fibrisolvens digests more fibre but cannot effectively compete with highly fibrolytic bacteria in the rumen

et al. 2001

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Aims: This study investigated the competitive abilities of two Neocallimastix patriciarum‐derived xylanases constructs in Butyrivibrio fibrisolvens H17c (xynA and pUMSX) and their ability to compete in vivo. Methods and Results: The digestibility of neutral detergent fibre (NDF) increased during co‐culture of xynA or pUMSX and weakly cellulolytic, but not with highly cellulolytic, ruminococci. Competition studies among xynA, pUMSX and cellulolytic consortia demonstrated that xynA was the fittest. XynA did not persist at high levels in the rumen and was undetectable after 22 days. Conclusions: The construction of recombinant xylanolytic B. fibrisolvens does improve the digestibility of fibre above that of the native, but digestibility is still less than that of the most potent fibre digesters such as ruminococci. Significance and Impact of the Study: Fibre digestion may be improved by genetic manipulation of ruminal bacteria but ecological parameters, such as persistence in vivo and the niche of the organism, must be taken into account.

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Genetically Modified Ruminal Bacteria Protect Sheep from Fluoroacetate Poisoning

Cited by 97 publications

References 9 publications

Isolation and survey of novel fluoroacetate-degrading bacteria belonging to the phylum Synergistetes

Isolation and survey of novel fluoroacetate-degrading bacteria belonging to the phylum Synergistetes

Opportunities to improve fiber degradation in the rumen: microbiology, ecology, and genomics

Expression of a modified Neocallimastix patriciarum xylanase in Butyrivibrio fibrisolvens digests more fibre but cannot effectively compete with highly fibrolytic bacteria in the rumen

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