[Polysaccharides of diatoms occurring in Lake Baikal].

Polysaccharide composition of neutral, acid- and alkali-soluble fractions of the diatoms Stephanodiscus meyerii Genkal et Popovsk and Aulacoseira baicalensis (K. Meyer) Simonsen of Lake Baikal has been studied. Neutral polysaccharides were represented by chrysolaminarans (1-->3;1-->6-beta-D-glucans). The chrysolaminaran from S. meyerii consists of the high- and low-molecular-weight fractions (40 and 2-5 kDa, respectively) and contains a large number of beta-1-->6-bound glucose residues. The chrysolaminaran from A. baicalensis is a low-molecular-weight 1-->3:1-->6-beta-D-glucan containing a small number of beta-1-->6 bonds, with mannitol being attached to the reducing unit of its chain. Acid- and alkali-soluble polysaccharide fractions are practically absent in S. meyerii. The alkali-soluble fraction from A. baicalensis is a low-molecular-weight (2-kDa) glycoprotein, the carbohydrate moiety of which is represented by a heteropolysaccharide.

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.

[Degradation of fucoidan by the marine proteobacterium Pseudoalteromonas citrea]. / Osobennosti degradatsii fukoidana morskimi proteobakteriiami Pseudoalteromonas citrea.

It was found that Pseudoalteromonas citrea strains KMM 3296 and KMM 3298 isolated from the brown algae Fucus evanescens and Chorda filum, respectively, and strain 3297 isolated from the sea cucumber Apostichopus japonicus are able to degrade fucoidans. The fucoidanases of these strains efficiently degraded the fucoidan of brown algae at pH 6.5-7.0 and remained active at 40-50 degrees C. The endo-type hydrolysis of fucoidan resulted in the formation of sulfated alpha-L-fucooligosaccharides. The other nine strains of P. citrea studied (including the type strain of this species), which were isolated from other habitats, were not able to degrade fucoidan.

[Screening of marine bacteria for fucoidan hydrolases]. / Poisk fukoidan-gidrolaz sredi morskikh mikroorganizmov.

Twenty-five strains of epiphytic marine bacteria isolated from the brown algae Fucus evanescens and Chorda filum and fifty-three bacteria isolated from the sea cucumber Apostichopus japonicus were screened for fucoidanases using fucoidans prepared from the brown algae F. evanescens, Laminaria cichorioides, and L. japonica. Eighteen bacterial epiphytes and thirty-eight bacterial isolates from the sea cucumber were found to contain fucoidanases, which were able to hydrolyze either all of the fucoidans studied or some of them. Bacteria of the genera Cytophaga and Alteromonas/Pseudoalteromonas exhibited the highest fucoidanase activities, which, however, did not exceed the activity of fucoidanases from the already known sources.

[Iodine concentration by the fungus Penicillium chrysogenum inhabiting soils of the nonchernozem zone]. / Kontsentrirovanie ioda gribom Penicillium chrysogenum, obitaiushchim v pochvakh Nechernozemnoi zony.

The iodine accumulation by strains of microscopic fungi Penecillium chrysogenum isolated from soddy-middle podzolic soils of Kirov region has been studied. It has been shown that fungi are able to accumulate from 5,0 X 10(-5) to 10,2% of iodine depending upon the medium iodine content and the degree of the organisms' tolerance to its high concentrations.

[Biochemical pathways of carbon monoxide assimilation in the carboxydobacterium, Pseudomonas gazotropha]. / Biokhimicheskie puti assimiliatsii ugarnogo gaza u karboksidobakterii Pseudomonas gazotrophe.

The incorporation of 14CO into acid-stable assimilation products by Pseudomonas gazotrophia Z-1156 is characterized by a slow rate at the beginning, contrary to the rectilinear kinetics for incorporation of the bicarbonate 14C in the presence of 12CO. The assimilation of 14C-bicarbonate decelerates in the absence of CO. The relative content of 14C is the highest in phosphorylated compounds upon the shortest possible incubation of the cells of P. gazotropha Z-1156 (5 min) in the presence of 14CO and O2, and decreases in the process of incubation. The bulk of radioactivity is found in aspartate and glutamate. The composition of products formed upon the assimilation of 14CO and NaH14CO3 (in the presence of 12CO) during 15 min is similar. The key enzymes of the reductive pentose phosphate cycle have been found in the cell extracts of P. gazotropha A-1156. The specific activity of carboxylating enzymes of the Calvin cycle in the cell extracts increases in the course of proportional growth and sharply decreases when the growth of the culture decelerates. The activity of ribulose diphosphate carboxylase (EC. 4.1.1.39) is always by one-two orders lower than that of ribulose phosphate isomerase (EC. 5.3.1.6) and phosphoribulokinase (EC.2.7.1.19), but is similar to the activity of phosphoenolpyruvate carboxylase (EC. 4.1.1.31). The activity of phosphoenolpyruvate carboxykinase (EC. 4.1.1.32) has not been detected in the cells extracts of P. gazotropha Z-1156.

[Pathways of assimilation of carbon oxides in carboxydobacteria Seliberia carboxydohydrogena and Achromobacter carboxydus]. / Puti assimiliatsii okislov ugleroda u karboksidovakterii Seliberia carboxydohydrogena i Achromobacter carboxydus.

Assimilation products of 14C-bicarbonate and carbon-14C oxide were studied in two carboxydobacteria Seliberia carboxydohydrogena and Achromobacter carboxydus which differed in their ability for chemolithoautrophous growth in the presence of hydrogen. The dynamics and composition of labeled products formed upon assimilation of 14C-bicarbonate in the presence of unlabeled carbon oxide by the two organisms, the composition of products formed upon assimilation of 14CO by suspensions of S. carboxydohydrogena Z-1062 during 5 minutes, and the dynamics and composition of labeled assimilates of A. carboxydus Z-1171 after incubation in the presence of 14CO, were found to be consistent with those expected in the action of the reductive pentose phosphate Calvin cycle. The similarity of products formed upon assimilation of 14CO2 and 14CO suggests that CO is first oxidized to CO2, and only is assimilated.