Gossypol detoxification in the rumen and Helicoverpa armigera larvae:A review

Gossypol,a phenolic compound found in the cotton plant,is widely distributed in cottonseed byproducts.Although ruminant animals are believed to be more tolerant of gossypol toxicity than monogastric animals due to rumen microbial fermentation,the actual mechanisms of detoxification remain unclear.In contrast,the metabolic detoxification of gossypol by Helicoverpa armigera(Lepidoptera:Noctuidae)larvae has achieved great advances.The present review discusses the clinical signs of go ssypol in ruminant animals,as well as summarizing advances in the study of gossypol detoxification in the rumen.It also examines the regulatory roles of several key enzymes in gossypol detoxification and transformation known in H.armigera.With the rapid development of modern molecular biotechnology and-omics technology strategies,evidence increasingly indicates that research into the biological degradation of gossypol in H.armigera larvae and some microbes,in terms of these key enzymes,could provide scientific insights that would underpin future work on microbial gossypol detoxification in the rumen,with the ultimate aim of further alleviating gossypol toxicity in ruminant animals.

The release and catabolism of ferulic acid in plant cell wall by rumen microbes:A review

Ferulic acid(FA)is one of the most abundant hydroxycinnamic acids in the plant world,especially in the cell wall of grain bran,in comparison with forage and crop residues.Previous studies noted that FA was mainly linked with arabinoxylans and lignin in plant cell walls in ester and ether covalent forms.After forages were ingested by ruminant animals or encountered rumen microbial fermentation in vitro,these cross-linkages form physical and chemical barriers to protect cell-wall carbohydrates from microbial attack and enzymatic hydrolysis.Additionally,increasing studies noted that FA presented some toxic effect on microbial growth in the rumen.In recent decades,many studies have addressed the relationships of ester and/or ether-linked FA with rumen nutrient digestibility,and there is still some controversy whether these linkages could be used as a predicator of forage digestibility in ruminants.The authors in this review summarized the possible relationships between ester and/or ether-linked FA and fiber digestion in ruminants.Rumen microbes,especially bacteria and fungi,were found capable of breaking down the ester linkages within plant cell walls by secreting feruloyl and p-coumaroyl esterase,resulting in the release of free FA and improvement of cell wall digestibility.The increasing evidence noted that these esterases secreted by rumen microbes presented synergistic effects with xylanase and cellulase to effectively hydrolyze forage cell walls.Some released FA were absorbed through the rumen wall directly and entered into blood circulation and presented antioxidant effects on host animals.The others were partially catabolized into volatile fatty acids by rumen microbes,and the possible catabolic pathways discussed.To better understand plant cell wall degradation in the rumen,the metabolic fate of FA along with lignin decomposition mechanisms are needed to be explored via future microbial isolation and incubation studies with aims to maximize dietary fiber intake and enhance fiber digestion in ruminant animals.