Genetic similarity of Streptococcus bovis in ruminants. (Abstract)

Abstract

25A Genetic similarity of Streptococcus bovis in ruminants M. Ghali1, P.T. Scott2 and R.A.M. Al Jassim 1 1 2 School of Animal Studies, University of Queensland, Gatton Qld 4343 Agricultural Molecular Biotechnology Laboratory, University of Queensland, Gatton Qld 4343 raj@sas.uq.edu.au The complexity of the rumen microbial ecosystem is widely acknowledged. Cellulolytic bacteria dominate the rumen microbial system when ruminants are fed fibre rich diets but the microbial population changes rapidly when ruminants are fed a starchrich diet; this results in a significant increase in the proportion of lactic acid producing bacteria, including Streptococcus bovis. This bacterium has been implicated in the development of lactic acidosis in grain fed cattle, sheep and horses. However, it is not known whether this bacterium is present in the rumen of the dromedary camel and the rusa deer and, if present, how similar it is to S. bovis isolates from cattle and sheep. In this report ruminal isolates of S. bovis from dromedary camel (MPR2 and MPR4) and rusa deer (RD11 and RD09) were compared with S. bovis isolates from cattle (R184 and R185), and sheep (R1 and R7). All animals were on roughage diet. The 16S rDNA was amplified by PCR from purified genomic DNA. The PCR products were analysed by RFLP with the MPR2 MPR4 restriction enzymes Hinf I and Dpn II and then cloned into pGEMT easy vector. The DNA sequence of each isolate was determined, and all sequences were compared by alignment with Clustal W. Isolates were also evaluated for their ability to utilize various carbohydrates, fermentation end products from glucose, and doubling time in BM10 broth with glucose (0.3% w/v; Table 1). All isolates of S. bovis had the same RFLP pattern with each of the two restriction enzymes (Figure 1). DNA sequence analysis showed more than 99% similarity among all isolates. The various isolates grew rapidly with an estimated doubling time (mean � SE) of 25 � 0.4 minutes. All isolates are homofermentative, producing Llactate. In addition to camel isolates and the deer isolate RD11 growing on glucose, cellobiose, fructose, galactose, inulin, lactose, maltose, mannose, raffinose, starch and sucrose, they also grew on arabinose. This report demonstrates how widely spread and similar S. bovis is in ruminant species. MPR2 MPR4 RD11 RD11 RD09 RD09 R184 R185 R184 R185 Kb R1 Kb R1 R7 a b Figure1 Restriction enzymes banding profile of 16S rDNA gene. (a) Hinf I, (b) Dpn II. Table 1 L_Lactate production, pH and doubling time of S. bovis from sheep, cattle, camel and deer. Isolates: L_Lactate (x103nM)* Final pH Doubling time (min) R1 130 5.9 27 R7 155 5.8 25 R184 125 5.8 25 R185 130 5.8 25 MPR2 115 6.1 25 MPR4 135 5.8 25 RD11 115 5.8 23 RD09 120 5.9 26 *The L_lactate produced from 83x103 nM glucose after 20 h incubation at 39oC Recent Advances in Animal Nutrition in Australia, Volume 14 (2003) R7