STREPTOCOCCUS-CAPRINUS SP-NOV, A TANNIN-RESISTANT RUMINAL BACTERIUM FROM FERAL GOATS

An undescribed bacterium capable of clearing tannic acid-protein complexes has been isolated from ruminal contents of feral goats browsing tannin-rich Acacia species. The bacterium is a Gram-positive facultative anaerobe, characterized as a Streptococcus, but DNA-DNA hybridization and 16S rDNA sequencing show that it is distinct from the common ruminal species Strep. bovis. We propose the name Streptococcus caprinus for this species. The type strain is Strep. caprinus 2.3, Australian Collection of Microorganisms (ACM) 3969. The bacterium grows in media containing at least 2.5% w/v tannic acid or condensed tannin and produces zones of clearing around colonies on nutrient agar plates with added tannic acid. Streptococcus caprinus is not a major inhabitant of domestic livestock, but is found in feral goats browsing tannin-rich Acacia species, at a population of up to 2 x 10(6) cfu ml-1 of rumen fluid.