Mikrobiol. Z. 2017; 79(6):13-27. Ukrainian.
Microbial Glycopolymers: Structure, Functional and Biological Activity
Zabolotny Institute of Microbiology and Virology, NAS of Ukraine
154 Akad. Zabolotny Str., Kyiv, 03143, Ukraine
In the department of biochemistry of microorganisms, the research is developing in two directions: 1) lipoposaccharides of the representatives of Enterobacteriaceae: Rahnella aquatilis, Pragia fontium, Budvivia aquatica, Pantoea agglomerans, Escherichia coli, their chemical identifcation, structural studies, functional and biological activity, 2) enzymes of glycolytic (α-L-rhamnosidase, α-galactosidase, α-amylase) and proteolytic (peptidase) action in Cryptococcus albidus, Eupenicillium erubescens, Aspergillus niger, Penicillium canescens, Cladosporium cladosporioides, Aspergillus oryzae, Yarowia lipolytica, representatives of the genus Bacillus. The structures of the O-specific polysaccharides (OPS) of R. acquatilis, P. fontium and B. aquatica are described for the frst time. They are constructed from chains represented by linear or branched tri-, tetra-, penta- and hexasaccharides. OPS of a number of strains are heterogeneous and contain two types of oligosaccharides, which difer in structure. Most OPS of the strains studied are heteropolysaccharides, while one strain of R. aquatilis 3-95 is represented by homopolysaccharides of mannose or glucose. Serological methods show the immunochemical heterogeneity of P. fontium, R. aquatilis and B. aquatica species. Studies of the E. coli L-19 O-antigen showed that it is characterized by a unique OPS structure that is not related to any of the E. coli clones described today and is the representative of a new serogroup not yet described in the literature. Using inhibitor analysis of the catalytic reaction by group chemical reagents and metal ions, certain functional groups have been established that take part in catalysis. Thus, it has been established that B. thuringiensis strain IMB B-7324 synthesizes peptidase with elastolytic and fbrinolytic activity, which is a serine alkaline peptidase. Analysis of the kinetic curves of the dependence of the rate of α-galactosidase and α-L-rhamnosidase activity on the pH allowed us to fnd the values of ionization constants of the groups that are involved in enzymatic catalysis and show that in the active center of A. niger, P. canescens, C. Cladosporioides α-galactosidases, and C. albidus and E. erubescens α-L-rhamnosidases, there are two groups that are ionized and that correspond to the carboxyl group of the C-terminal acid and the imidazole group of histidine. The presence of an imidazole group was also confrmed by a specifc reaction - photooxidation in the presence of methylene blue. The calculated value of the ionization heat corresponded to the heat of the ionization of the imidazole group. The important role of the carbohydrate part of the glycosidases studied in the formation of the oligomeric structure, in secretion, resistance to high temperatures and other factors of the aggressive environment, as well as to proteolysis is shown. Studies of substrate specifc enzymes make it possible to predict their practical use in the future.
Key words: lipopolysaccharide, proteases, α-galactosidase, α-amylase, α-L-rhamnosidase, microbial producers.
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