Fluoroacetate in plants - a review of its distribution, toxicity to livestock and microbial detoxification

Abstract

Fluoroacetate producing plants grow worldwide and it is believed they produce this toxic compound as a defence mechanism against grazing by herbivores. Ingestion by livestock often results in fatal poisonings, which causes significant economic problems to commercial farmers in many countries such as Australia, Brazil and South Africa. Several approaches have been adopted to protect livestock from the toxicity with limited success including fencing, toxic plant eradication and agents that bind the toxin. Genetically modified bacteria capable of degrading fluoroacetate have been able to protect ruminants from fluoroacetate toxicity under experimental conditions but concerns over the release of these microbes into the environment have prevented the application of this technology. Recently, a native bacterium from an Australian bovine rumen was isolated which can degrade fluoroacetate. This bacterium, strain MFA1, which belongs to the Synergistetes phylum degrades fluoroacetate to fluoride ions and acetate. The discovery and isolation of this bacterium provides a new opportunity to detoxify fluoroacetate in the rumen. This review focuses on fluoroacetate toxicity in ruminant livestock, the mechanism of fluoroacetate toxicity, tolerance of some animals to fluoroaceate, previous attempts to mitigate toxicity, aerobic and anaerobic microbial degradation of fluoroacetate, and future directions to overcome fluoroacetate toxicity.

Keywords: 1080; Aerobic; Anaerobic; Degradation; Dehalogenase; Fluoroacetate; Synergistetes; TCA; Toxicity.

Fig. 1

Distribution of fluoroacetate bearings plants in Australia. Black dots Gastrlobium spp., grey dots Acaia georginae, generated from the Atlas of Living Australia 15/05/2017 (http://www.ala.org.au/)

Fig. 2

Production of 5´-fluorodeoxyyadenosine (FDA) from S-adenosyl-L-l-methionine (Adomet) by Fluorinase reaction (3–4). Formation of Fluoroaceate (FAc) and 4-fluorothreonine (4-FT) from (4 to 1–2). Incorporation of Isotope labelled Glycerol (5 and 8 to 3)

Fig. 3

Mechanisms of fluoroacetate toxicity

Fig. 4

The mechanism of dehalogenation by fluoroacetate dehalogenase in Delftia acidovorans