Characterisation of tannin-resistant bacteria from the rumen fluid of feral goats and camels with restriction analysis of amplified 16S rDNA

Acacia sp. and Caliandra callothyrsus contain tannin at concentration of 8-11 % DM. These legumes can only be digested by ruminants that naturally adapt to feed with high tannin content. This capability is due to the presence of tannin-resistant bacteria in their rumen, such as Streptococcus caprinus and Selenomonas ruininantium K2, which were isolated from the rumen fluid of feral goats browsing Acacia. Other tannin-resistant bacteria also exist in the rumen. These bacteria have been isolated recently from the rumen fluid of feral goats and camels in enrichment experiments using tannic acid or tannin extracts from Acacia and Caliandra leaves as limiting substrates. These tannin-resistant bacteria were grouped morphologically into Gram-positive streptococci (6 isolates), Gram-positive cocci/rods (3 isolates), Gram-negative coccus (I isolate), Gram-negative curved rods (6 isolates), and Gram-negative slender rods (4 isolates). These isolates have been identified by physiological and biochemical tests, as well as API test, and the possible genera are Streptococcus sp., Leuconostoc sp. or Lactobacillus sp., Megasphaera sp. or Prevotella sp., Selenomonas sp., Butyrivibrio sp. or Clostridium sp. Confirmation of these genera is still necessary, for example, by the use of a molecular approach. The present study was conducted to characterise tannin-resistant bacteria using 16S rDNA restriction fragment length polymorphism (RFLP) analysis. This method was capable of identifying isolates that belong to Streptococcus sp. and Selenomonas sp. The other two isolates appeared to be Lictobacillus sp. and Butyrivibrio sp. However, restriction analysis of amplified 16S rDNA did not characterise Gram-negative coccus to be the same genus as identified phenotypically. This bacterium could be characterised by sequencing its amplified 16S rDNA as Escherichia coli. This method also confirmed the identification of the other two isolates to be Lactobacillus sp. and Butyrivibrio sp. This study indicated that restriction analysis of amplified 16S rDNA followed by sequencing of 16S rDNA are useful for characterisation of tannin-resistant bacteria. This characterisation is important to study the role of tannin-resistant bacteria to digest legume leaves that contained tannin at high concentration.