Research interests

Microbiology, biochemistry, genomics and molecular ecology of microbial hydrolysis of cellulose, hemicelulose and chitin in the animal and human digestive tract.

Butyrate producing bacteria

Our studies focused on the butyrate-producing bacteria originated with transformation of Butyrivibrio fibrisolvens isolates with pBHf plasmid, carrying dehalogenase gene. Expressed dehalogenase in the rumen was able to detoxify plant fluoroacetate, a common toxin in Australian and South African plants. The transformation was successful with a very low number of isolates, indicating a high variability in isolates of motile, butyrate-producing anaerobic rods from the rumen. The high variability was also observed in fermentation products, extracellular polysaccharides, cell wall monosaccharides, hydrolytic activities, restriction barriers, C+G content and DNA sequences. Phylogenetic trees of 16S rDNA revealed at least 8 new or closely related bacterial species to Butyrivibrio fibrisolvens. To clarify the relations among the isolates, we have described two new species: Butyrivibrio hungatei and Pseudobutyrivibrio xylanivorans. The former one is utilizing a narrow spectrum of oligo- and monosaccharides on the opposite to P. xylanivorans, which is utilizing a wide spectrum of polysaccharides, proteins and nucleic acids. The latter species is dominating in the population of butyrate producing bacteria in the rumen under different feeding conditions. We have participated on the reclassification of the Butyrivibrio proteoclasticus. The counts were confirmed by selective counting methods, by cPCR, and RT PCR, both we have developed for Butyrivibria and Pseudobutyrivibria.

Anaerobic fungi

Monocentric and polycentric fungi in the rumen produce very efficient hydrolytic enzymes and in case of ß-1,4-endoglucanase, the fungal specific activity is the highest ever observed. Our attention is focused on the occurrence and properties of Anaeromyces isolates in the digestive tract of herbivorous animals. Species of this genus are very efficient fiber degraders and there is not deep knowledge about their properties, taxonomic position and interactions with other microbes in the rumen. The cell wall of anaerobic fungi is based on chitin molecules. Therefore it is clear that other chitinolytic microbes are able to limit the growth of anaerobic fungi.

Chitinolytic microorganisms

We have described a chitinolytic bacterial population in the digestive tract of herbivorous animals. In the chitinolytic population are prevailing Clostridium species. Pure strains are able to slow down or eliminate growth of rumen fungi in vitro. The sensitivity of anaerobic fungi to bacterial chitinases differs significantly from genus to genus. Similar chitinolytic bacteria were isolated from digesta of human colon. The presence of these bacteria there could reflect the eating habits of our ancestors.