Submitted to: Systematic and Applied Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/23/2002
Publication Date: 12/5/2002
Citation: RUSSELL, J.B., GARNER, M.R., FLINT, J.P. 2002. ALLISONELLA HISTAMINIFORMANS gen. nov., sp. nov.: A NOVEL BACTERIUM THAT PRODUCES HISTAMINE, UTILIZES HISTIDINE AS ITS SOLE ENERGY SOURCE, AND COULD PLAY A ROLE IN BOVINE AND EQUINE LAMINITIS. SYSTEMATIC AND APPLIED MICROBIOLOGY. 25:498-506. Interpretive Summary: Cattle in the United States are fed grain supplements to increase productivity, but these supplements can cause a decrease ruminal pH, rumen ulcers, liver abscesses and laminitis (sore feet). Laminitis is the chief reason why dairy cattle are forced to leave the milking herd. Laminitis is aggravated by histamine production in the rumen. Histamine is powerful inflammatory agent that dilates the blood vessels above the hoof. It had generally been assumed that histamine was produced by ruminal lactobacilli, but our work indicated that a previously unidentified bacterium was more important. 16S rDNA and physiological tests indicated that the bacterium should be assigned a new genus and species. We propose the name Allisonella histabacter. Research on ruminal histamine production has the potential to alleviate this painful and ultimately lethal disease.
Technical Abstract: When cattle and horses are fed large amounts of grain, histamine can accumulate in the gastrointestinal tract, and this accumulation can cause an acute inflammation of the hooves (laminitis). When ruminal fluid from dairy cattle fed grain supplements was serially diluted in anaerobic MRS medium containing histidine (50 mM), histamine was detected at dilutions as high as 10-7. The histidine enrichments were then transferred successively in an anaerobic, carbonate-based medium (50 mM histidine) without glucose. The histamine producing bacteria could not be isolated from the rumens of cattle fed hay, but similar histamine producing bacteria could be isolated the feces of cattle fed grain and the cecum of a horse. All of the histamine producing isolates had the same ovoid morphology. The cells stained gram negative and were resistant to the ionophore, monensin (25 µM). The doubling time was 110 min, and the yield was 1.5 mg cell protein per mmol histidine. The G+C content was 46.8%. Lysine was the only other amino acid used, but lysine did not allow growth if histidine was absent. Because carbohydrate and organic acid utilization was not detected, it appeared that the isolates used histidine decarboxylation as their sole mechanism of energy derivation. 16s rDNA sequencing indicated that the isolates were most closely related to low G+C gram positive bacteria (firmicutes), but similarities were less than or equal to 94%. Because the most closely related bacteria (Dialister pneumonsintes, Megasphaera elsdenii and Selenomonas ruminantium) did not produce histamine from histidine, we propose that these histamine producing bacteria be assigned to a new genus, Allisonella, as Allisonella histabacter gen. nov., sp. nov. The type strain is MR2.