Optimization of cold-adapted alpha-galactosidase expression in Escherichia coli.

α-Galactosidase (α-PsGal) of the cold-adapted marine bacterium Pseudoalteromonas sp. KMM 701 was cloned into the pET-40b(+) vector to study its properties and to develop an effective method for modifying human B-erythrocytes into O-blood group. The use of heat-shock as a pre-induction treatment, IPTG concentration of 0.2 mM and post-induction cultivation at 18 °C for 20 h in the developed MX-medium allowed increasing the recombinant Escherichia coli Rosetta (DE3)/40Gal strain productivity up to 30 times and the total soluble α-PsGal yield up to 40 times.

Intracellular alginolytic enzymes of the marine bacterium Pseudoalteromonas citrea KMM 3297.

The marine bacterium Pseudoalteromonas citrea KMM 3297 is an associate of the holothurian Apostichopus japonicus. When grown in a medium containing glucose, the strain produces two intracellular alginolytic enzymes, AlI and AlII. Fucoidan from the brown alga Fucus evanescens induces synthesis of one more alginolytic enzyme, AlIII. These enzymes were separated using anion-exchange chromatography. The alginate lyase AlI completely retains its activity at 35 degrees C, AlII and AlIII being stable at 45 degrees C. The alginate lyases exhibit maximal activities in the range of pH 7-8. The molecular weights of AlI, AlII, and AlIII determined by gel filtration are 25, 79, and 61 kD, respectively. All the investigated enzymes are endo-type alginate lyases. They catalyze degradation of polyguluronate (poly-G) and polymannuronate (poly-M) yielding oligosaccharides of the polymerization degree of 5 > or = n > or = 3 with the unsaturated bond between the C4 and C5 atoms of the non-reducing terminus. A mixture of these three enzymes exhibits synergism while acting on the polymeric substrate. The Km values of the alginate lyase AlI for poly-G and poly-M are 24 and 34 micro g/ml, respectively. Alginate lyase AlIII exhibits less affinity to poly-M (Km = 130.0 microg/ml) than to poly-G (Km = 40.0 microg/ml). NaCl (0.2 M), MgCl2 and MgSO4 (0.01 M) activate all three enzymes more than twofold. The presence of several alginolytic enzymes of different specificity provides efficient destruction of alginic acids of brown algae by the strain P. citrea KMM 3297.

Ecophysiological variabilities in ectohydrolytic enzyme activities of some Pseudoalteromonas species, P. citrea, P. issachenkonii, and P. nigrifaciens.

The ecophysiological variabilities in the ectohydrolytic enzyme profiles of the three species of Pseudoalteromonas, P. citrea, P. issachenkonii, and P. nigrifaciens, have been investigated. Forty-one bacteria isolated from several invertebrates, macroalgae, sea grass, and the surrounding water exhibited different patterns of hydrolytic enzyme activities measured as the hydrolysis of either native biopolymers or fluorogenic substrates. The activities of the following enzymes were assayed: proteinase, tyrosinase, lipase, amylase, chitinase, agarase, fucoidan hydrolase, laminaranase, alginase, pustulanase, cellulase, beta-glucosidase, alpha- and beta-galactosidases, beta-N-acetylglucosaminidase, beta-glucosaminidase, beta-xylosidase, and alpha-mannosidase. The occurrence and cell-specific activities of all enzymes varied over a broad range (from 0 to 44 micromol EU per hour) and depended not only on taxonomic affiliation of the strain, but also on the source/place of its isolation. This suggests 'specialization' of different species for different types of polymeric substrates as, for example, all strains of P. citrea and P. issachenkonii hydrolyzed alginate and laminaran, while strains of P. nigrifaciens were lacking the ability to hydrolyze most of the algal polysaccharides. The incidence of certain enzymes such as fucoidan hydrolases, alginate lyases, agarases, and alpha-galactosidases might be strain specific and reflect its particular ecological habitat.

Alpha-N-acetylgalactosaminidase from marine bacterium Arenibacter latericius KMM 426T removing blood type specificity of A-erythrocytes.

An alpha-N-acetylgalactosaminidase IV able to remove blood type specificity of human A(II)-erythrocytes and not effecting B(III)-erythrocytes was isolated from the marine bacterium Arenibacter latericius KMM 426T. The alpha-N-acetylgalactosaminidase IV preparation exhibits high activity during inhibition of hemagglutination with blood group substance A containing determinants analogous to A-erythrocytes. The enzyme has a pH optimum from 7.0 to 8.0 and completely retains its activity during 30-min heating at 50 degrees C and for a week at 20 degrees C. The enzyme can be stored under the sterile conditions for any length of time at 4 degrees C, but it does not withstand freezing. The alpha-N-acetylgalactosaminidase is resistant to NaCl; for p-nitrophenyl-alpha-N-acetyl-D-galactosaminide, the Km is 0.38 mM. The molecular mass of the enzyme determined by gel filtration is 84 kD.

Two species of culturable bacteria associated with degradation of brown algae Fucus evanescens.

The heterotrophic microbial enrichment community established during degradation of brown algae Fucus evanescens was characterized. A two-species bacterial community of marine culturable gamma-proteobacteria consisted of Pseudoalteromonas and Halomonas. The first member of the community, Pseudoalteromonas sp., was highly metabolically active, had bacteriolytic and hemolytic activities, produced proteinases (gelatinase and caseinase), lipases, DNases, and fucoidanhydrolases, laminaranases, alginases, pustulanases, beta-glucosidases, beta-galactosidases, beta-N-acetylglucosaminidases, and beta-xylosidases. The second member of the community, Halomonas marina, produced only caseinase and DNase, and it did not hydrolyze algal polysaccharides. Both members of the studied bacterial community utilized a range of easily assimilable monosaccharides and other low molecular weight organic substances. The results provide an evidence of the complex metabolic interrelations between two members of this culturable community. One of them Pseudoalteromonas sp., most likely plays the major role in the initial stages of algal degradation; the other one, H. marina, resistant to the bacteriolytic activity of the former, is able to utilize the products of degradation of polysaccharides.