Degradation of Fucoidan by the Marine Proteobacterium 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°C. The endo-type hydrolysis of fucoidan resulted in the formation of sulfated -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.     

Distribution of intracellular fucoidan hydrolases among marine bacteria of the family Flavobacteriaceae

A search for fucoidan-degrading enzymes and other O-glycosylhydrolases has been performed among 51 strains of marine bacteria of the family Flavobacteriaceae isolated from red, green, and brown algae, as well as from the sea urchin Strongylocentrotus intermedius and the holothurian Apostichopus japonicus. Over 40% of the studied strains synthesized fucoidanases. The marine bacteria Mesonia algae KMM 3909^T (an isolate from green alga Acrosiphonia sonderi), as well as Maribacter sp. KMM 6211 and Gramella sp. KMM 6054 (associants of the sea urchin S. intermedius), were the best producers of fucoidanases. Xylose effectively induced the biosynthesis of fucoidanases in these strains. None of the 15 strains of marine bacteria belonging to the genus Arenibacter produced polysaccharide hydrolases.     

Flavobacterium ahnfeltiae sp. nov., a new marine polysaccharide-degrading bacterium isolated from a Pacific red alga

A Gram-negative, aerobic, rod-shaped, motile by gliding and yellow-pigmented bacterium, designated strain 10Alg 130^T, that displayed the ability to destroy polysaccharides of red and brown algae, was isolated from the red alga Ahnfeltia tobuchiensis. The phylogenetic analysis based on 16S rRNA gene sequence placed the novel strain within the genus Flavobacterium, the type genus of the family Flavobacteriaceae, the phylum Bacteroidetes, with sequence similarities of 96.2 and 95.7 % to Flavobacterium jumunjiense KCTC 23618^T and Flavobacterium ponti CCUG 58402^T, and 95.3–92.5 % to other recognized Flavobacterium species. The prevalent fatty acids of strain 10Alg 130^T were iso-C_15:0, iso-C_15:0 3-OH, iso-C_17:0 3-OH, C_15:0 and iso-C_17:1ω9c. The polar lipid profile consisted of phosphatidylethanolamine, two unknown aminolipids and three unknown lipids. The DNA G+C content of the type strain was 34.3 mol%. The new isolate and the type strains of recognized species of the genus Flavobacterium could strongly be distinguished by a number of phenotypic characteristics. A combination of the genotypic and phenotypic data showed that the algal isolate represents a novel species of the genus Flavobacterium, for which the name Flavobacterium ahnfeltiae sp. nov. is proposed. The type strain is 10Alg 130^T (=KCTC 32467^T = KMM 6686^T).     

Occurrence and diversity of mesophilic Shewanella strains isolated from the North-West Pacific Ocean

Although bacteria of the genus Shewanella belong to one of the readily cultivable groups of "Gammaproteobacteria", little is known about the occurrence and abundance of these microorganisms in the marine ecosystem. Studies revealed that of 654 isolates obtained from marine invertebrates (ophiuroid Amphiopholis kochii, sipuncula Phascolosoma japonicum, and holothurian Apostichopus japonicus, Cucumaria japonica), seawater and sediments of the North-West Pacific Ocean (i.e. the Sea of Japan and Iturup Is, Kurile Islands), 10.7% belonged to the genus Shewanella. The proportion of viable Shewanella species varied from 4% to 20% depending on the source of isolation. From the isolation study, representative strains of different phenotypes (from seventy presumptive Shewanella strains) were selected for detailed characterization using phenotypic, chemotaxonomic, and phylogenetic testing. 16S rDNA sequence-based phylogenetic analysis confirmed the results of tentative identification and placed the majority of these strains within only a few species of the genus Shewanella with 98-99% of 16S rDNA sequences identity mainly with S. japonica and S. colwelliana, suggesting that the strains studied might belong to these species. Numerically dominant strains of S. japonica were metabolically active and produced proteinases (gelatinases, caseinases), lipases, amylases, agarases, and alginases. Shewanella strains studied demonstrated weak antimicrobial and antifungal activities that might be an indication of their passive role in the colonization on living and non-living surfaces.     

An unusual lipid a from a marine bacterium Chryseobacterium scophtalmum CIP 104199T

The hydrolysis of defatted cells of the marine bacterium Chryseobacterium scophtalmum CIP 104199^T with 10% acetic acid (3 h, 100°C) led to an unusual lipid A (LA) (yield 0.6%), obtained for the first time. Using chemical analysis, FAB MS, and NMR spectroscopy, it was shown to be D-glucosamine 1-phosphate acylated with (R)-3-hydroxy-15-methylhexadecanoic and (R)-3-hydroxy-13-methyltetroadecanoic acids at the C2 and C3 atoms, respectively. It is similar to the monosaccharide biosynthetic precursor of lipopolysaccharide (LPS), so-called lipid X (LX). Unlike LX, LA can be isolated by the treatment of bacteria with organic solvents only after the preliminary acidic hydrolysis of the cells, which suggests that LA might be strongly, probably chemically, linked to other components of the outer membrane. However, LPS cannot be such a component, because extraction with phenol-water or phenol-chloroform-petroleum ether mixtures in high yields (5.34% and 0.5%, respectively) leads to preparations that do not contain 3-deoxy-D-manno-oct-2-ulopyranosonic acid, 3-hydroxyalkanoic acids, or LA.     

Molecular Characterization and Therapeutic Potential of a Marine Bacterium Pseudoalteromonas sp. KMM 701 α-Galactosidase

An α-galactosidase capable of converting B red blood cells into the universal blood type cells at the neutral pH was produced by a novel obligate marine bacterium strain KMM 701 (VKM B-2135 D). The organism is heterotrophic, aerobic, and halophilic and requires Na⁺ ions and temperature up to 34°C for its growth. The strain has a unique combination of polysaccharide-degrading enzymes. Its single intracellular α-galactosidase exceeded other glycoside hydrolases in the level of expression up to 20-fold. The α-galactosidase was purified to determine the N-terminal amino acid sequences and new activities. It was found to inhibit Corynebacterium diphtheria adhesion to host buccal epithelium cell surfaces with high effectiveness. The nucleotide sequence of the homodimeric α-galactosidase indicates that its subunit is composed of 710 amino acid residues with a calculated Mr of 80,055. This α-galactosidase shares structural property with 36 family glycoside hydrolases. The properties of the enzyme are likely to be highly beneficial for medicinal purposes.     

Polaribacter reichenbachii sp. nov.: A New Marine Bacterium Associated with the Green Alga Ulva fenestrata

A Gram-negative, aerobic, rod-shaped, motile by gliding and yellow-pigmented bacterium, designated strain 6Alg 8^T, was isolated from the common Pacific green alga Ulva fenestrata. The phylogenetic analysis based on 16S rRNA gene sequence placed the novel strain within the genus Polaribacter, a member of the family Flavobacteriaceae, the phylum Bacteroidetes, with sequence similarities of 97.6 % to Polaribacter dokdonensis DSW-5^T and 92.8–96.1 % to other recognized Polaribacter species. The prevalent fatty acids of strain 6Alg 8^T were iso-C_15:0, iso-C_15:1, iso-C_15:0 2-OH, C_15:0 and C_15:1ω6. The polar lipid profile consisted of the major lipids phosphatidylethanolamine, two unknown aminolipids and one unknown lipid. The DNA G+C content of the type strain is 31.6 mol%. The new isolate and the type strains of recognized species of the genus Polaribacter were readily distinguished based on a number of phenotypic characteristics. A combination of the genotypic and phenotypic data showed that the algal isolate represents a novel species of the genus Polaribacter, for which the name Polaribacter reichenbachii sp. nov. is proposed. The type strain is 6Alg 8^T (= KCTC 23969^T = KMM 6386^T = LMG 26443^T).