Withdrawn Australian Society for Microbiology Annual Scientific Meeting 2013

Tannin-Degrading Bacteria in the Faeces of South Australian and Queensland Koalas (#249)

Dena Piro 1 , Natasha Speight 1 , Manouchehr Khazandi 1 , Sam Abraham 1 , Amber Gillett 2 , Wayne Boardman 1 , Darren Trott 1
  1. The University of Adelaide, Roseworthy, SA, Australia
  2. Australia Zoo Wildlife Hospital, Queensland, Australia

The eucalypt diet of the koala is high in tannins which limit the availability of energy and nutrients in the diet. Although little is known about how koala hindgut bacteria digest tannins, several tannin-protein-complex-degrading (TPCD) bacteria have been isolated from the faeces of captive Queensland koalas, including Lonepinella koalarum, a new genus and species within the Pasteurellaceae family hypothesized to be the most important TPCD bacteria in the koala hindgut. The aim of this study was to isolate and identify tannin-degrading bacteria from the faeces of koalas in both South Australia and Queensland, focusing on Gram-negative organisms including Lonepinella koalarum. Fresh faecal samples were collected from koalas from three locations; Kangaroo Island (n=63), Cleland Wildlife Park, Adelaide (n=45) and Queensland (n=58). Samples were inoculated onto Wilkins-Chalgren anaerobe agar (WCAA), tannin-overlayed WCAA (T-WCAA), and vancomycin-infused T-WCAA (T-V-WCAA), and incubated at 37°C for 72h. Prevalence of TPCD bacteria was recorded and colonies grouped according to morphology, Gram stain and biochemical characteristics. Gram-negative bacteria phenotypically consistent with Lonepinella koalarum were selected for 16S rDNA sequencing. The Kangaroo Island population exhibited a lower prevalence of tannin-degrading bacteria (71%), compared to Cleland (91%) and Queensland (100%). TPCD E. coli were more prevalent in all three locations compared to other coliform groups (predominantly Enterobacter and Klebsiella spp.). Although Lonepinella koalarum was identified in all three locations its prevalence was significantly lower in Kangaroo Island koalas compared to Cleland (p=0.0005) and Queensland (p=0.0205) (Kangaroo Island 4%, Cleland 31.6% and Queensland 23.5%, koalas), suggesting that it may not be an essential member of the autochthonous microbiota.