Novel sialidase from non-pathogenic bacterium Oerskovia paurometabola strain O129.

Bacterial sialidases are enzymes that are involved in a number of vital processes in microorganisms and in their interaction with the host or the environment. Their wide application for scientific and applied purposes requires the search for highly effective and non-pathogenic producers. Here, we report the first description of sialidase from Oerskovia paurometabola. The extracellular enzyme preparation was partially purified. The presence of sialidase was confirmed in native PAGE treated with the fluorogenic substrate 4MU-Neu5Ac. Maximum enzyme activity was registered at 37 °C and in the pH range of 4.0-5.5. The influence of metal ions and EDTA was examined. It was demonstrated that EDTA, Mn2+ and Ba2+ ions inhibit the sialidase activity to different extent, while Cd2+, Fe2+ and Fe3+ have stimulating effect on it. These features are studied for the first time concerning sialidase of Oerskovia representative. Cell bound sialidase and sialate aldolase were also established.

Rapid screening of plasmid-encoded small hsp-genes in Streptococcus thermophilus.

A new rapid procedure for detection of small heat shock protein genes (shsp) was developed. Using PCR-based molecular approach, single colonies of 49 Streptococcus thermophilus industrial and artisanal starters were examined. Five strains contained plasmid-encoded shsp. The nucleotide sequence analysis revealed that the genes are very conservative, as only a few nucleotide substitutions were noticed. It was shown that all new isolated plasmids belong to the pC194 family of rolling circle replicating (RCR) plasmids. We concluded that shsp genes are always inherited together with pC194-type replicative region. The viability of plasmid-bearing and plasmid-free derivatives of S. thermophilus strain ST2980 under heat shock condition was studied.