December 21, 2011: Asian elephant is indigenous to many countries including Thailand, but fermenter microorganisms in gastrointestinal tract of the elephant have not fully been investigated. Therefore, this study aimed to observe the cellulolytic bacteria in Genus Ruminococcus in large intestines of captive Asian elephants (Elephas maximus).
Fecal samples were collected from male and female sucklings, young and adult captive Asian elephants. Forty-four elephants were divided into 3 groups as followed: A) > 18 years old (n=24); B) 2-18 years old (n=17) and C) < 2 years old (n=3). The results revealed that there were 214 (42.8%) isolates of R. flavefaciens, 105 (21.0%) isolates of R. bromii, 90 (18.0%) isolates of R. obeum, 54 (10.8%) isolates of R. callidus and 37 (7.4%) isolates of R. albus from all fecal samples examined. Interestingly, Ruminococcus strains could be isolated from the weaned elephants, but were not found in the sucklings (p<0.05). In conclusion, cellulolytic bacteria in Genus Ruminococcus were isolated from the large intestines of captive Asian elephants. Moreover, the highest prevalence of the bacteria was found in the elephants aged more than 18 years old.
Elephants are herbivorous animals and hindgut-fermenters. The gastrointestinal tract (GI tract) of the elephant is similar to other hindgutfermenter, including horses and rabbits. Hindgutfermenters have no gall bladder (Langka, 2002). Biological degradation of dietary fiber; cellulose, hemicellulose, takes place in rumen of ruminant or cecum of horse, rabbit and elephant. Cecal folders assist in the increase in nutrient absorption area through cecal epithelium (McBee, 1971). Moreover, there are many kinds of microorganism inside cecum which mostly are anaerobic bacteria, fungi and protozoa (Forsberg et al., 1997; Koike et al., 2000). These microorganisms play an important role in the cellulose fermentation (Forsberg et al., 1997). Cellulolytic bacteria are most prevalent inside the cecum. They produce enzymes to ferment cellulose and hemicellulose into short-chain fatty acids which are easily absorbed such as primarily acetate, propionate, butyrate, or amino acids (Russell and Wilson, 1996). Microbial ecosystem in rumen of ruminant and cecum of horse are well-studied and used as a good model to study cellulolytic bacteria in elephants. Predominant strains of cellulolytic bacteria in rumen are Fibrobacter succinogenes, Ruminococcus flavefaciens and R. albus (Julliand et al., 1999; Koike et al., 2000; Chen and Weimer, 2001; Koike and Kobayashi, 2001). Ruminococcus spp. has also been isolated from cecum of horse (Julliand et al., 1999). Ruminococcus spp. is a non-motile obligatory anaerobic gram-positive coccoid bacterium. It is an important normal flora because it is able to produce xylanase, cellulase and esterase for the biosynthesis of cellulose, hemicellulose and pectin within the gastrointestinal tract (Wang et al., 1997). Thereby, this bacterium is important for herbivorous animals to serve an energy source. Even though identification of this bacterium by a conventional method is recommended, it still depends on the experience of bacteriologist. Therefore, the molecular techniques have been demonstrated and reported in the previous investigations to assist the identification of these bacteria (Wolin, 1981; Russell and Wilson, 1996; Wang et al., 1997; Julliand et al., 1999; Koike et al., 2000; Chen and Weimer, 2001; Koike and Kobayashi, 2001; Wang et al., 2004; Hastie et al., 2008). Presently microflora, particularly cellulolytic bacterium in GI tract of elephant, has not fully been investigated and needs to be clarified. Therefore, this study aimed to observe the cellulolytic bacteria in Genus Ruminococcus isolated from fecal samples of captive Asian elephants (Elephas maximus) and to clarify the predominant strain of Genus Ruminococcus in elephants of different ages. Download the complete report in pdf format here.