(i) new isolates of up till now undescribed Spirochaeta sp. (ii) isolation and identification of the bacterial species Pseudobutyrivibrio xylanivorans (iii) chemotaxonomic identification of the new bacterial species Butyrivibrio hungatei (iv) detailed phenotypic and genotypic characterization of new rumen Spirochaetae spp. (v) an extensive gene sequence listing of bacterial ssu rRNA, inhabiting the bovine, horse and land crab intestine; (vi) cloned and sequenced gene for an unspecific P. bryantii nuclease (vii) cloned and sequenced the pPTC18 cryptic plasmid; ( viii) the whole nucleotide sequence of xylanse Xyn T from Pseudobityrivibrio xylanivorans, aminoacid sequence and placement in family 11 of hydrolases (ix) new oligonucleotide probes (rsp. PCR oligonucleotide primers) for rumen spirochaete; (x) protocol preparation: PCR based rumen spirochaete detection, in situ hybridization and flow cytometry detection of acetogenic bacteria and cPCR detection of soil pseudomonads and rumen Butyrivibrio spp. (xi) contributing to the extension of Comet assay applicability based on some new eukaryotic organisms and cell lines tests. (xii) experimentally proved and statistically tested protocols for the assessment of genotoxicity in potable water by a combination of comet assay on culture hepatocytes, AMES test and micronucleus test (xiii) a new model for quantitative evaluation of anaerobic bacteria attachment on human colon wall