Antifouling activity of sessile bacilli derived from marine surfaces.

Marine biofilms are a virtually untapped source of bioactive molecules that may find application as novel antifoulants in the marine paint industry. This study aimed at determining the potential of marine biofilm bacteria to produce novel biomolecules with potential application as natural antifoulants. Nine representative strains were isolated from a range of surfaces and were grown in YEB medium and harvested during the late exponential growth phase. Bacterial biomass and spent culture medium were extracted with ethanol and ethyl acetate, respectively. Extracts were assayed for their antifouling activity using two tests: (1) antimicrobial well diffusion test against a common fouling bacterium, Halomonas marina, and (2) anti-crustacean activity test using Artemia salina. Our results showed that none of the ethanolic extracts (bacterial biomass) were active in either test. In contrast, most of the organic extracts had antimicrobial activity (88%) and were toxic towards A. salina (67%). Sequencing of full 16 S ribosomal DNA analysis showed that the isolates were related to Bacillus mojavensis and Bacillus firmus. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF-MS) profiling of ethyl acetate extracts of culture supernatants showed that these species produce the bioactive lipopeptides surfactin A, mycosubtilin and bacillomycin D.

Petrotoga halophila sp. nov., a thermophilic, moderately halophilic, fermentative bacterium isolated from an offshore oil well in Congo.

A novel thermophilic, moderately halophilic, rod-shaped bacterium, strain MET-B(T), with a sheath-like outer structure (toga) was isolated from an offshore oil-producing well in Congo, West Africa. Strain MET-B(T) was a Gram-negative bacterium with the ability to reduce elemental sulfur, but not sulfate, thiosulfate or sulfite into sulfide. The optimum growth conditions were 60 degrees C, pH 6.7-7.2 and 4-6 % NaCl. The DNA G+C content was 34.6 mol%. Strain MET-B(T) was phylogenetically related to members of the genus Petrotoga; Petrotoga miotherma, Petrotoga olearia and Petrotoga mexicana were the closest relatives, with type strains exhibiting more than 99 % identity in an analysis of small-subunit rRNA gene sequences. The values for DNA-DNA relatedness between the type strains of these three species and strain MET-B(T) were less than 42 %. As MET-B(T) was found to be genetically and physiologically different from other species of the genus Petrotoga, this strain is proposed as representing a novel species, for which the name Petrotoga halophila sp. nov. is proposed. The type strain is MET-B(T) (=DSM 16923(T)=CCUG 50214(T)).

Petrotoga mexicana sp. nov., a novel thermophilic, anaerobic and xylanolytic bacterium isolated from an oil-producing well in the Gulf of Mexico.

A novel anaerobic, thermophilic, xylanolytic, motile rod-shaped bacterium with a sheath-like outer structure (toga) was isolated from a Mexican oil well in the Gulf of Mexico. Strain MET12T was a Gram-negative bacterium, reducing elemental sulfur, thiosulfate and sulfite to hydrogen sulfide. Its optimum growth conditions were 55 degrees C, pH 6.6, 3% NaCl and 0.15% MgCl2.6H2O. The DNA G+C content was 36.1 mol%. Phylogenetically, strain MET12T was related to members of genus Petrotoga, with similarities to Petrotoga mobilis, Petrotoga sibirica, Petrotoga miotherma and Petrotoga olearia varying from 97.6 to 98.8%. However DNA-DNA relatedness values between these species and strain MET12T were lower than 70%. As strain MET12T (=DSM 14811T=CIP 107371T) was genomically and phenotypically different from existing Petrotoga species, it is proposed as the type strain of a novel species, Petrotoga mexicana sp. nov.

Garciella nitratireducens gen. nov., sp. nov., an anaerobic, thermophilic, nitrate- and thiosulfate-reducing bacterium isolated from an oilfield separator in the Gulf of Mexico.

A novel Gram-positive, anaerobic and thermophilic bacterium, strain MET79(T), was isolated from an oil well located in the Gulf of Mexico. Cells were straight rods, motile by a subpolar flagellum. Spores were formed in old cultures. Inner gas vacuoles swelled the cells when exposed to air. The optimum growth conditions were 55 degrees C, pH 7.5 and 1 % NaCl. Yeast extract was required for growth. Strain MET79(T) fermented several sugars, some organic acids and Casamino acids. Glucose was fermented into lactate, acetate, butyrate, H(2) and CO(2). Strain MET79(T) reduced thiosulfate to hydrogen sulfide and nitrate to ammonium. The DNA G+C content was 30.9 mol%. The closest phylogenetic relative of strain MET79(T) was Caloranaerobacter azorensis (88.7 % 16S rDNA sequence similarity). As strain MET79(T) (=DSM 15102(T)=CIP 107615(T)) was physiologically and phylogenetically different from its closest relatives, it is assigned as the type strain of a novel species of a new genus, Garciella nitratireducens gen. nov., sp. nov.

Desulfovibrio capillatus sp. nov., a novel sulfate-reducing bacterium isolated from an oil field separator located in the Gulf of Mexico.

A new spirilloid sulfate-reducing bacterium designated strain MET2(T) (T=type strain), was isolated from a Mexican oil field separator. Electron microscopy revealed a Gram-negative cell wall consisting of a 150nm thick undulating outer membrane. Strain MET2(T) appeared singly or in long chains and was actively motile with a corkscrew-like motion. The isolate grew optimally at 40 degrees C, pH 7.4 and 3% NaCl in a medium containing lactate, thiosulfate and yeast extract. Sulfate, sulfite, thiosulfate, and elemental sulfur served as electron acceptors but not nitrate or fumarate. Lactate, pyruvate and H(2) (with acetate as carbon source) were used as electron donors. Pyruvate was fermented. Desulfoviridin and cyt c were present. The G+C content of the DNA was 58.7mol%. Phylogenetic analysis based on 16S rDNA sequencing showed that strain MET2(T) was a member of the genus Desulfovibrio with "D. gracilis" and D. longus being its closest relatives (similarities of 98.3% and 97.1%, respectively). However, DNA-DNA hybridization studies indicated poor homologies (values <70%) with both species. On the basis of genotypic, phenotypic, and phylogenetic characteristics, strain MET2(T) (=DSM14982(T)=CIP107483(T)) is proposed as the type strain of a new species, Desulfovibrio capillatus sp. nov. GenBank accession number for the 16S rDNA sequence for MET2(T) is AY176773.