Free-radical depolymerization with metallic catalysts of an exopolysaccharide produced by a bacterium isolated from a deep-sea hydrothermal vent polychaete annelid

Free-radical depolymerization with metallic catalysts has been investigated to depolymerize an exopolysaccharide (EPS), with a high molecular weight (>10⁶ g/mol), produced by the bacterium Alteromonas macleodii subsp. fijiensis biovar deepsane. Three metals (copper, zinc and manganese) were used either alone or mixed. These metals led to the depolymerization of the high molecular weight bacterial polysaccharide with different efficiency. This study specifies some conditions required to produce, with good reproducibility and yield, EPS derivatives of reduced molecular weight ranging from 100,000 to 20,000 g/mol. The more influential parameters are specified. This is a first study to find suitable industrial conditions in the presence of these metallic catalysts.     

Isolation and structure elucidation of a new antifungal and antibacterial antibiotic produced by Streptomyces sp. 201

An antibacterial and antifungal antibiotic was isolated from the culture filtrate of Streptomyces sp. 201, and its structure was determined as 2-methyl-heptyl isonicotinate by extensive use of NMR spectroscopy. The compound exhibited marked antimicrobial activity against Bacillus subtilis, Shigella sp., Klebsiella sp., E. coli, Proteus mirabilis, and the pathogenic fungi, Fusarium moniliforme, F. semitectum, F. oxysporum, F. solani and Rhizoctonia solani.     

A novel polymer produced by a bacterium isolated from a deep-sea hydrothermal vent polychaete annelid

AIMS: The objective of the present work was to describe an aerobic, mesophilic and heterotrophic marine bacterium, designated HYD657, able to produce an exopolysaccharide (EPS). It was isolated from a East Pacific Rise deep-sea hydrothermal vent polychaete annelid. METHODS AND RESULTS: This micro-organism, on the basis of the phenotypical features and genotypic investigations, can be clearly assigned to the Alteromonas macleodii species and the name A. macleodii subsp. fijiensis biovar deepsane is proposed. Optimal growth occurs between 30 and 35 degrees C, at pH between 6.5 and 7.5 and at ionic strengths between 20 and 40 g x l(-1) NaCl. The G + C content of DNA was 46.5%. This bacterium excreted, under laboratory conditions, an EPS consisting of glucose, galactose, rhamnose, fucose and mannose as neutral sugars along with glucuronic and galacturonic acids and a diacidic hexose identified as a 3-0-(1 carboxyethyl)-D-glucuronic acid. Its average molecular mass was 1.6 x 10(6) Da. CONCLUSIONS: The bacterium HYD657, for which the name A. macleodii subsp. fijiensis biovar deepsane is proposed, produces an unusual EPS in specific medium. SIGNIFICANCE AND IMPACT OF THE STUDY: Due to its interesting biological activities, applications have been found in cosmetics. Its probable contribution to the filamentous microbial mat in the Alvinella pompejana microenvironment can be also mentioned.     

Purification and properties of an anti-B hemagglutinin produced by Streptomyces sp.

An anti-B hemagglutinin was purified to homogeneity from the culture filtrate of a strain of Streptomyces sp. by affinity chromatography. The Streptomyces hemagglutinin was adsorbed to insolubilized gum arabic and eluted with 1 M NaCl containing 1 M D-galactose. The purified hemagglutinin is thought to be homogeneous judging from sodium dodecyl sulfate-polyacrylamide gel electrophoresis at pH 7.2, disc gel electrophoresis at pH 4.3, isoelectric focusing, and ultracentrifugation. The molecular weight was estimated to be 11,000 from results of gel filtration in 6 M guanidine hydrochloride (Gdn-HCl), sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and sedimentation equilibrium analysis. The amino acid analyses revealed that the hemagglutinin contained large amounts of alanine, glycine, and valine, 47% of the total amino acid residues, and no phenylalanine. Carbohydrate analysis demonstrated that the hemagglutinin might not be a glycoprotein. The circular dichroic (CD) spectrum of the protein is quite different from those of usual proteins in having a large positive peak at 226 nm (theta = 10,000) and a negative band at 212 nm (theta =-2600). The hemagglutinin showed a typical precipitation curve with gum arabic, and agglutinated human blood group B erythrocytes 256 times as strongly as A or O erythrocytes. These activities were not affected by pH (from 4 to 12). The anti-B activity was further confirmed by serological tests. The hemagglutination-inhibition studies indicated that D-galactose was inhibitory, but alpha-D-galactosides were not necessarily better inhibitors than beta-D-galactosides. L-Rhamnose was the best inhibitor among the monosaccharides tested, and L-arabinose and D-fucose were also inhibitory.     

Thermosipho japonicus sp. nov., an extremely thermophilic bacterium isolated from a deep-sea hydrothermal vent in Japan

A novel barophilic, extremely thermophilic bacterium was isolated from a deep-sea hydrothermal vent chimney at the Iheya Basin, in the Okinawa area, Japan. The cells were found to be rod shaped and surrounded by a sheath-like outer structure; the organism did not possess flagella and was not motile. Growth was observed between 45° and 80°C (optimum, 72°C, 45 min doubling time), pH 5.3 and 9.3 (optimum, pH 7.2–7.6), 6.6 and 79 g/l sea salts (optimum, 40 g/l), and 0.1 and 60 MPa (optimum, 20 MPa). Strain IHB1 was found to be a strictly anaerobic chemoorganotroph capable of utilizing yeast extract and proteinaceous substrates such as peptone and tryptone. Elemental sulfur or thiosulfate acted as electron acceptors improving growth. The isolate was able to utilize casein as a sole carbon and energy source in the presence of thiosulfate. The G + C content of the genomic DNA was 31.4 mol%. Phylogenetic analysis based on 16S rDNA sequences and DNA–DNA hybridization analysis indicated that the isolate is closely related to Thermosipho africanus; however, it represents a species distinct from the previously described members of the genus Thermosipho. On the basis of the physiological and molecular properties, we propose that the new isolate represents a new species, which we name Thermosipho japonicus sp. nov. (type strain: IHB1; JCM10495). Received: May 26, 1999 / Accepted: August 7, 1999     

Alteromonas infernus sp. nov., a new polysaccharide-producing bacterium isolated from a deep-sea hydrothermal vent

A deep-sea, aerobic, mesophilic and heterotrophic new bacterium was isolated from a sample of fluid collected among a dense population of Riftia pachyptila , in the vicinity of an active hydrothermal vent of the Southern depression of the Guaymas basin (Gulf of California). On the basis of phenotypic and phylogenetic analyses and DNA/DNA relatedness, the strain GY785 was recognized as a new species of the genus Alteromonas and the name of Alteromonas infernus is proposed. During the stationary phase in batch cultures in the presence of glucose, this bacterium secreted two unusual polysaccharides. The water-soluble exopolysaccharide-1 produced xrcontained glucose, galactose, galacturonic and glucuronic acids as monosaccharides. The gel-forming exopolysaccharide-2 was separated from the bacterial cells by dialysis against distilled water and partially characterized.     

一株深海热液口嗜热芽孢杆菌SY27F代谢产物活性的研究

【目的】对一株来源于深海热液口嗜热芽孢杆菌的次生代谢产物进行抑菌活性和抗肿瘤活性的初步研究。【方法】采用纸片法和微量肉汤稀释法检测嗜热芽孢杆菌SY27F次生代谢产物的抑菌活性,采用CCK-8法测定其次生代谢产物的抗肿瘤活性。【结果】抑菌实验表明,嗜热芽孢杆菌代谢产物对大肠杆菌、金黄色葡萄球菌均有抑菌作用,其最低抑菌浓度分别为1.56 mg/mL和3.13 mg/mL;细胞实验表明,其代谢产物对肿瘤细胞A549、HepG2、HeLa、MCF-7均有一定的抑制作用,其半致死浓度分别为0.390、0.451、0.704、1.105 mg/mL;与人肝肿瘤细胞(HepG2)相比,其对人正常肝细胞(L02)表现出良好的生物相容性。【结论】嗜热芽孢杆菌SY27F次生代谢产物具有一定的抑菌和抗肿瘤活性,可为寻找新型抑菌抗肿瘤活性物质提供优质资源。     

Characterization of a thermotolerant laccase produced by Streptomyces sp. SB086

Laccases have become desirable enzymes for application in many industrial processes. Nowadays, most of these enzymes are obtained from fungi. Among prospective studies for bacterial laccase genes, some have included actinomycetes, but only a few studies have characterized the enzyme produced. Thus, we have isolated a laccase-producing actinomycete from forest soil under restoration process and further aimed to characterize its produced enzyme. The isolate SB086 was assigned to the Streptomyces genus by a combination of phenotypical, chemical and phylogenetic properties. Our data indicate that the bacterium produces a thermotolerant laccase. The maximum activity was obtained in the pH range 4.0–5.0 and at 50 °C in reaction mixture containing 5 mM CuSO₄; thermal stability was noted at 60 °C and 70 °C—a well-desired characteristic for industry. The active enzyme presented a high molecular mass (over 100 kDa) and was less sensitive to inhibition by metal ions than generally described for bacterial laccases. Our findings support in silico data of bacterial laccase secretion, and reinforce the view that actinomycetes may be a rich source of laccase for industrial application.     

Eptatretus strickrotti n. sp. (Myxinidae): first hagfish captured from a hydrothermal vent

A single hagfish (Myxinidae, Eptatretus) specimen was recently captured at a hydrothermal vent site on the East Pacific Rise (38 degrees S). This is the first capture of a member of the jawless fishes (agnathans) from a hydrothermal vent site. The specimen differs from all congeners by the very slender body (depth 2.9% of total length), the paired and median ventral nasal sinus papillae, and the presence of 10 afferent branchial arteries on the medial ventral aorta. It is further unique because of a combination of the following features: slime pore counts; paired dorsal nasal sinus papillae; 12 gill pouches and gill apertures; posterior left side of body widely separated from pharyngocutaneous duct; 3/2 multicusp configuration; ventral aorta bifurcated anteriorly between 2nd and 3rd gill pouches (counted from the snout toward the heart); and pink coloration. The specimen is here described as a new species named Eptatretus strickrotti. Molecular 16S rRNA data places this new species as the basal-most species of Eptatretus, providing important new insight to the evolution of hagfishes as a whole.     

Halomonas profundus sp. nov., a new PHA-producing bacterium isolated from a deep-sea hydrothermal vent shrimp

Aims:  The objective of the present work was to describe a new deep-sea, aerobic, mesophilic and heterotrophic bacterium, referenced as strain AT1214, able to produce polyhydroxyalkanoates (PHAs) under laboratory conditions. This bacterium was isolated from a shrimp collected nearby a hydrothermal vent located on the Mid-Atlantic Ridge. Methods and Results:  This micro-organism, on the basis of the phenotypical features and genotypic investigations, can be clearly assigned to the Halomonas genus and the name of Halomonas profundus is proposed. Optimal growth occurred between 32 and 37°C at a pH between 8 and 9 and at ionic strength between 20 and 30 g l⁻¹ of sea salts. The G + C content of DNA was 58·6%. This bacterium produced PHAs of poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from different carbon sources. Conclusions:  The bacterium H. profundus produces PHA of 3HB and 3HV monomers from different carbon sources. Significance and Impact of the Study:  PHAs share physical and material properties that suggest them for application in various areas, and are considered as an alternative to nonbiodegradable plastics produced from fossil oils. In this study, we describe a new bacteria isolated from a deep-sea hydrothermal vent with the capability to produce polyesters of biotechnological interest.     

Antifungal activity of valinomycin, a peptide antibiotic produced by Streptomyces sp. Strain M10 antagonistic to Botrytis cinerea

A strain of Streptomyces sp. (M10) antagonistic to Botrytis cinerea was isolated from orchard soil obtained from Jeju Island, Korea. An antifungal substance (CN1) was purified from the culture extracts of the strain, and then identified as valinomycin through extensive spectroscopic analyses. Valinomycin showed potent in vitro antifungal activity against Botrytis cinerea and also in vivo control efficacy against Botrytis blight development in cucumber plants. Overall, the disease control efficacy of valinomycin was similar to that of vinclozolin, a commercial fungicide. This study provides the first report on the disease control efficacy of valinomycin against Botrytis blight.