Metabolism of tannin-protein complex by facultatively anaerobic bacteria isolated from koala feces
Ro Osawa,1 Terry P. Walsh2 & Steven J. Cork3
1Veterinary' Service & Research, Lone Pine Koala Sanctuary, Fig Tree Pocket, Brisbane, Queensland 4069, Australia
2Centre for Molecular Biotechnology, School of Life Science, Queensland University of Technology, Faculty of Science, Gardens Point Campus, Brisbane Queensland 4001, Australia
3 CSIRO Division of Wildlife and Ecology, Lyneham, ACT 2602, Australia
The metabolic pathways involved in degradation of tannin-protein complex (T-PC) were investigated in various facultatively anaerobic bacteria, with specific reference to fecal isolates from the koala including T-PCdegrading entcrobacteria (T-PCDE), Streptococcus bovis, Klebsiella pneumoniae, and K. oxytoca. It was demonstrated that T-PCDE and S. bovis biotype I were capable of degrading protein complexed with gallotannin (a hydrolyzable tannin), but not that complexed with quebracho (a condensed tannin). Subsequent studies showed that these strains metabolized gallic acid to pyrogallol. Strains of Klebsiella pneumoniae and K. oxytoca, which did not degrade T-PC, also metabolized gallic acid into pyrogallol. Pyrogallol was not degraded by any strains studied, but it was not detected in fresh feces of the koalas. The majority of strains isolated from feces could degrade phloroglucinol. Based on these findings, we propose that members of the gut microflora of the koala cooperate in the degradation of T-PC.