Biochemical composition of the marine conditioning film: implications for bacterial adhesion

The conditioning film formed on glass panels was analysed for total carbohydrates (CFCHO), total proteins (CFP) and total uronic acids (CFURA). The influence of these compounds on the adhesion of three marine bacterial cultures, Pseudomonas sp. CE-2, Pseudomonas sp. CE-10 and Bacillus sp. SS-10 was also evaluated. One-way analysis of variance suggested a significant increase in the attachment of all three cultures to conditioned glass panels. Moreover, CE-2 (r = 0.874) and CE-10 (r = 0.879) showed a significant positive correlation with CFCHO. Conversely, SS-10 (r = -0.69) showed a significant negative correlation with CFCHO. Backward multiple linear regression analysis indicated that CFCHO were the most predictive component of the conditioning film in explaining bacterial adhesion to the conditioned glass panels.     

Chemical characterization of exopolysaccharides from the marine fouling diatom amphora coffeaeformis

Amphora coffeaeformis cells were grown in batch cultures under continuous illumination at 18°C for 10 d. Algal cells were removed by centrifugation, lyophilized and used for the extraction of exopolysaccharides using either 0.05 M EDTA, 1 M NaOH or 1.5 M NaCl. The 1.5 M NaCl treatment removed most exopolysaccharides. Glucose (81%) was the most abundant monosaccharide in the exopolysaccharides. The chemical composition data suggest that the exopolymers were acidic sulphated polysaccharides containing high concentrations of pyruvate (22%) and uronic acids (18%). These polysaccharides may play an important role in metal complexation and protection from desiccation in A. coffeaeformis.     

Chemical characterization and quantification of siderophores produced by marine and terrestrial aspergilli

Ten aspergilli (five each from marine and terrestrial habitats) were screened for siderophore production. All test isolates produced siderophores as indicated by a positive reaction in the FeCl(3) test, chrome azurol sulphonate assay, and chrome azurol sulphonate agar plate test. Further, the test isolates were compared for their siderophore production potential and chemical characteristics. Examination of the chemical nature of the siderophores revealed that all test isolates produced hydroxamate siderophores that were trihydroxamate hexadentates. Wide-spread occurrence of siderophores in marine isolates indicate their functional role in maintaining overall productivity of coastal waters. Among all test aspergilli, marine Aspergillus versicolor was found to be the largest siderophore producer (182.5 microg/mL desferrioxamine mesylate equivalent), least siderophore production was recorded in a marine strain of Aspergillus niger (3.5 microg/mL desferrioxamine mesylate equivalent).     

Discovery and characterization of a marine bacterial SAM-dependent chlorinase

Halogen atom incorporation into a scaffold of bioactive compounds often amplifies biological activity, as is the case for the anticancer agent salinosporamide A (1), a chlorinated natural product from the marine bacterium Salinispora tropica. Significant effort in understanding enzymatic chlorination shows that oxidative routes predominate to form reactive electrophilic or radical chlorine species. Here we report the genetic, biochemical and structural characterization of the chlorinase SalL, which halogenates S-adenosyl-L-methionine (2) with chloride to generate 5'-chloro-5'-deoxyadenosine (3) and L-methionine (4) in a rarely observed nucleophilic substitution strategy analogous to that of Streptomyces cattleya fluorinase. Further metabolic tailoring produces a halogenated polyketide synthase substrate specific for salinosporamide A biosynthesis. SalL also accepts bromide and iodide as substrates, but not fluoride. High-resolution crystal structures of SalL and active site mutants complexed with substrates and products support the S(N)2 nucleophilic substitution mechanism and further illuminate halide specificity in this newly discovered halogenase family.     

Short- and long-term conditioning of a temperate marine diatom community to acidification and warming

Ocean acidification and greenhouse warming will interactively influence competitive success of key phytoplankton groups such as diatoms, but how long-term responses to global change will affect community structure is unknown. We incubated a mixed natural diatom community from coastal New Zealand waters in a short-term (two-week) incubation experiment using a factorial matrix of warming and/or elevated pCO₂ and measured effects on community structure. We then isolated the dominant diatoms in clonal cultures and conditioned them for 1 year under the same temperature and pCO₂ conditions from which they were isolated, in order to allow for extended selection or acclimation by these abiotic environmental change factors in the absence of interspecific interactions. These conditioned isolates were then recombined into ‘artificial’ communities modelled after the original natural assemblage and allowed to compete under conditions identical to those in the short-term natural community experiment. In general, the resulting structure of both the unconditioned natural community and conditioned ‘artificial’ community experiments was similar, despite differences such as the loss of two species in the latter. pCO₂ and temperature had both individual and interactive effects on community structure, but temperature was more influential, as warming significantly reduced species richness. In this case, our short-term manipulative experiment with a mixed natural assemblage spanning weeks served as a reasonable proxy to predict the effects of global change forcing on diatom community structure after the component species were conditioned in isolation over an extended timescale. Future studies will be required to assess whether or not this is also the case for other types of algal communities from other marine regimes.     

Extraction and characterization of an exopolysaccharide from a marine bacterium

International Microbiology - The marine bacterial exopolysaccharides (EPS) have transfigured the biotech sector with their myriad applications and prospects. This work was carried out to...     

Purification and characterization of a new kappa-carrageenase from a marine Cytophaga-like bacterium

A bacterial strain able to degrade various sulfated galactans (carrageenans and agar) was isolated from the marine red alga Delesseria sanguinea. From the cell-free supernatant of cultures grown on crude lambda-carrageenan, a kappa-carrageenase was purified by ammonium sulfate fractionation, gel filtration on Sephacryl S 200 HR and ion-exchange chromatography on DEAE--Sepharose-CL6B. The purified kappa-carrageenase was detected as a single protein upon SDS/PAGE. Its molecular mass was estimated at 40 kDa. Activity was observed against kappa-carrageenan over the pH range 5.0-8.5 and was optimal at pH 7.2 in Tris buffer or 7.0 in Mops buffer. The enzyme activity remained stable at 30 degrees C, but only for up to 1 h at 40 degrees C. Analysis of the degradation products of the kappa-carrageenase by gel filtration and 13C-NMR spectroscopy indicated that the enzyme degrades kappa-carrageenan down to the level of the kappa-neocarratetraose sulfate. The properties of this new enzyme are compared with those of previously characterized carrageenases.     

Isolation and characterization of marine methanotrophs

Four new methane-oxidizing bacteria have been isolated from marine samples taken at the Hyperion sewage outfall, near Los Angeles, CA. These bacteria require NaCl for growth. All exhibit characteristics typical of Type I methanotrophs, except they contain enzyme activities of both the ribulose monophosphate pathway and the serine cycle. All four strains are characterized by rapid growth in liquid culture and on agar plates, and all have temperature optima above 35° C. One strain, chosen for further study, has been shown to maintain broadhost range cloning vectors and is currently being used for genetic studies.     

Flow cytometric characterization of marine microbes

The analysis of marine phytoplankton using flow cytometry has enabled the discovery of new taxa and has contributed new understanding to the dynamics and ecological contributions of phytoplankton to the global carbon cycle. Marine phytoplankton are uniquely suited to analysis by flow cytometry because of their size, pigment content, and ability to remain in suspension. Cytometric analysis of marine populations is not without challenges. Phytoplankton communities span a broad range of sizes. The smallest microbes are a few tenths of a micron, while the largest are a few tenths of a millimeter. The improvement of cytometric measurements of scattered laser light allows one to investigate marine microbes whose sizes span several orders of magnitude. To effectively leverage the advantages that marine microbes possess, cytometers have to be carefully engineered for marine use.     

Chemical and cryo-fixation for cadmium retention in a marine snail.

In the hepatopancreas of the marine snail Littorina littorea, tissue structure and elemental analysis are both adversely affected by dosage with cadmium (Cd) and preservation with an aqueous fixative saturated with hydrogen sulphide (H₂S). The fixative, with and without H₂S, leaches the intracellular phosphate and carbonate granules but the latter are more severely leached when H₂S is added. When intracellular accumulations of cadmium are examined by X-ray microanalysis (XRMA) cadmium retention is not enhanced by H₂S. To obtain a balanced XRMA of cadmium with other labile elements like Mg and K, it is necessary to use cryo-fixation.     

Chemical signaling processes in the marine environment

Understanding the mechanisms by which environmental chemical signals, chemical defenses, and other chemical agents mediate various life-history processes can lead to important insights about the forces driving the ecology and evolution of marine systems. For chemical signals released into the environment, establishing the principles that mediate chemical production and transport is critical for interpreting biological responses to these stimuli within appropriate natural, historical contexts. Recent technological advancements provide outstanding opportunities for new discoveries, thus allowing quantification of interactions between hydrodynamic, chemical, and biological factors at numerous spatial and temporal scales. Past work on chemically mediated processes involving organisms and their environment have emphasized habitat colonization by larvae and trophic relationships. Future research priorities should include these topics as well as courtship and mating, fertilization, competition, symbiosis, and microbial chemical ecology. There are now vast new opportunities for determining how organisms respond to chemical signals and employ chemical defenses under environmentally realistic conditions. Integrating these findings within a larger ecological and evolutionary framework should lead to improved understanding of natural physicochemical phenomena that constrain biological responses at the individual, population, and community levels of organization.     

Isolation and characterization of surfactant degrading bacteria in a marine environment

Abstract Sea water and sediment samples taken near the coasts of Hyeres bay (France) were used for anionic surfactant titrations with surface and bottom waters and the finest part of sediments. The capacity for surfactant degradation by the 'in situ' microflora was evaluated. By using a selective plating technique 26 strains able to utilize anionic surfactant were isolated from the selected bacterial communities. Their ability to degrade anionic surfactant was verified according to the biodegradation standard method. Isolated strains were characterized by morphological and physiological properties using API 20 NE micro-method. All tested strains were Gram negative, strictly aerobic, rod or helical shaped. Their weak utilization of phenolic substrates suggests that they degrade preferentially the alkyl chain of the surfactant molecule. Biodegradation was more efficient with bacterial communities rather than with any isolated strains. Such observations indicate that complete mineralization involves several other so far non-isolated strains which complete the degradation initiated by the isolated strains.     

Chemical screening of Brazilian marine algae producing carrageenans

The yield, IR spectra, 3,6-anhydro-d-galactose and sulfate content are given for several species of putative carrageenophytes from different sites on the Brazilian coast. Kappa carrageenan was found in Hypnea musciformis and Gigartina spp. ; all the other species tested yield an iota type. The lowest carrageenan yield was found in Cryptonemia crenulata (5%), and the highest in Gigartina sp. (72%); 3,6-anhydrogalactose content was highest in Hypnea musciformis and Gigartina spp., whereas sulfate was lowest in H. musciformis. Slight variations in the yield of carrageenans were found during the period of observation (March 1988 to May 1989), but no clear pattern could be recognized. No significant variation was observed in plants from different collection sites.     

Chemical characterization of fungal siderophores

Siderophores of twenty fungi belonging to Zygomycotina (5 Mucorales), Ascomycotina (7 aspergilli, 6 penicillia, Neurospora crassa) and Deuteromycotina (Fusarium dimerum) were examined for their chemical nature. Siderophores produced by fungi other than Mucorales were all hydroxamates. Mucorales produced carboxylate siderophores. Catecholate type of siderophores were not detectable. Hydroxamate siderophores were mostly (9 out of 15) trihydroxamates, while six were dihydroxamates. Monohydroxamate nature was not shown by any of the 15 test fungal siderophores. In ligand properties, 12 out of 15 hydroxamate siderophores formed hexadentate ligands, while two formed tetradentates and one bidentate. There was good correlation between number of hydroxamate groups and ligand property.     

Isolation and characterization of filterable marine bacteria

Anderson, J. I. W. (Northeast Shellfish Sanitation Research Center, Narragansett, R.I.), and W. P. Heffernan. Isolation and characterization of filterable marine bacteria. J. Bacteriol 90:1713-1718. 1965.-By a process of double filtration of seawater, first through a membrane filter with a pore diameter of 0.45 mu and then through a membrane filter with a pore diameter of 0.22 mu, it was possible to isolate on the surface of the latter membrane a group of marine organisms not usually encountered by conventional techniques of pour plates or one-stage filtration. Many of the isolates could not be identified, but the largest single group belonged to the genus Spirillum; other isolates were placed in the genera Leucothrix, Flavobacterium, Cytophaga, and Vibrio. A group of four organisms which was not identified was characterized by the formation of large, club-shaped cells, 20 to 30 mu long. Of the 25 strains studied in detail, 22 required seawater for growth and 8 retained their filterable property after cultivation. No filterable bacteria were isolated from terrestrial samples.     

Discovery and structural characterization of a novel glycosidase family of marine origin

The genomic data on heterotrophic marine bacteria suggest the crucial role that microbes play in the global carbon cycle. However, the massive presence of hypothetical proteins hampers our understanding of the mechanisms by which this carbon cycle is carried out. Moreover, genomic data from marine microorganisms are essentially annotated in the light of the biochemical knowledge accumulated on bacteria and fungi which decompose terrestrial plants. However marine algal polysaccharides clearly differ from their terrestrial counterparts, and their associated enzymes usually constitute novel protein families. In this study, we have applied a combination of bioinformatics, targeted activity screening and structural biology to characterize a hypothetical protein from the marine bacterium Zobellia galactanivorans, which is distantly related to GH43 family. This protein is in fact a 1,3-α-3,6-anhydro-l-galactosidase (AhgA) which catalyses the last step in the degradation pathway of agars, a family of polysaccharides unique to red macroalgae. AhgA adopts a β-propeller fold and displays a zinc-dependent catalytic machinery. This enzyme is the first representative of a new family of glycoside hydrolases, especially abundant in coastal waters. Such genes of marine origin have been transferred to symbiotic microbes associated with marine fishes, but also with some specific human populations.     

Isolation and characterization of a marine bacterium capable of utilizing 2-methylphenanthrene

A marine bacterium isolated from a coastal hydrocarbon-polluted sediment has been described and attributed on the basis of its phenotypic and genotypic characteristics to the genus Sphingomonas sp. This strain was capable of using an alkylated phenanthrene 2-methylphenanthrene, as sole source of carbon and energy. In experiments, 2-methylphenanthrene (0.2 g/l) was added as crystals to the culture medium. After 5 days of aerobic growth at 30 °C, 70% was degraded and the complete dissipation occurred after 20 days. Furthermore, the strain could degrade various kinds of polyaromatic compounds, but failed to grow on aliphatic hydrocarbons. Received: 27 December 1996 / Received last revision: 10 June 1997 / Accepted: 14 June 1997     

Isolation and characterization of marine oligotrophic bacteria

A significant part of the world ocean is characterized by low absolute nutrients and chlorophyll concentrations. In these oligotrophic environments, bacteria are very abundant and play a vital role in the remineralization of the dissolved organic matter. Bacteria adapted to oligotrophic waters differ from those adapted to richer environments by some genetic and metabolic characteristics. Culture techniques in bacteriology are based on rich media and do not allow the growth of most marine bacteria. New techniques have been developed for the culture of oligotrophic bacteria, which allow to isolate unknown bacteria. Pelagibacter ubique and Sphingopyxis alaskensis belong to these bacteria recently isolated from the marine environment and their study yielded better understanding of how marine bacteria adapt to oligotrophic conditions.     

Isolation and characterization of chitinase from a marine bacterium Vibrio sp.

A chitinase was separated from the culture broth of Vibrio sp. 11211 isolated from sediment from the South China Sea. The chitinase was purified 18.3-fold with 33% recovery by ammonium sulphate precipitation and chromatography. The subunit molecular weight of the enzyme was estimated by SDS-PAGE to be about 30kDa. The enzyme showed optimum pH at 6.5 and optimum temperature at 50^°C, and was stable in the pH range of 4 to 9 and at the temperature below 40^°C.