Browsing by Author "Korkeela, Tiina"

It is estimated that the human large intestine harboring thousands of different bacterial species. Human intestinal microbiota is considered play a role of otherwise indigestible dietary compounds. The microbiota also synthesise vitamins and has a role in formation of the immune system. The majority of the bacterial species present in the colon are obligate anaerobic and belong to Eubacterium rectale ? Blautia coccoides (Erec) and Clostridium leptum (Clept) groups and Phylum Bacteroidetes. The microbiota in the human intestine is quite diverse and the composition varies between individuals. Recently, only a minority of the intestinal microbiota has been cultured, and most of the intestinal microbiota is still non-cultivable by any available culture- based methods. Today most of the researchers use molecular-based methods to characterize the intestinal microbiota, and several recent studies have created a large number of sequences that many times correspond to “uncultured bacterium clones”. The majority of intestinal bacteria are known as “uncultured bacteria” and their presence in the intestine has only been observed without culturing. The aim of this study was to characterize new human fecal “uncultured bacteria” isolates using culture-based methods and gain more information about these bacteria. Isolates for this study were chosen based on their 16S rRNA gene sequence identification (sequence similarity with the nearest cultured bacteria ? 97 %). In this study, we were able to culture sixteen novel obligate anaerobic ”uncultured bacteria” isolates and they were partly characterized using culture-based techniques. Eleven isolates belonging to the Phylum Firmicutes, three to the Phylum Actinobacteria and two to the Phylum Bacteroidetes. We explore e.g. their growth requirements, cell- and colony morphology, production of enzymes, acid and bile tolerance and antibiotic susceptibility. In this study, we gain some information on phenotypic properties of the isolates. For taxonomic purposes and for naming new isolates, they should be characterized as comprehensively as possible. Therefore, more study is needed. Some of the culture-based methods did not work, and we did not obtain accurate results. This is partly due to used culture mediums that did not enable good growth for all isolates. The best bacterial growth was observed by using Reinforced Clostridial Medium (RCM). For this reason, the use of this medium for different biochemical test should be investigated. Only one of the isolates did not grow on RCM medium. Also, RCM medium was not suitable for determination the optimum pH for growth of bacteria. In this study, the best culture mediums for isolation of novel ”uncultured bacteria” isolates were PYG+VFA (peptone-yeast extract-glucose with volatile fatty acids) and YCFTA (yeast extract-casitone-fatty acids) mediums.