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Surface-active compounds (SACs) are widely used in different industries as well as in many daily consumption products. However, with the increasing concern for their environmental acceptability, attention has turned towards biological SACs which are biodegradable, less toxic and more environmentally friendly. In this work, 176 marine hydrocarbon-degrading bacterial isolates from petroleum-contaminated sites along the Norwegian coastline were isolated and screened for their capacity to produce biological SACs. Among them, 18 isolates were capable of reducing the surface tension of the culture medium by at least 20 mN m−1and/or capable of maintaining more than 40% of the emulsion volume after 24 h when growing on glucose or kerosene as carbon and energy source. These isolates were members of the generaPseudomonas,Pseudoalteromonas,Rhodococcus,Catenovulum, Cobetia,Glaciecola,Serratia,MarinomonasandPsychromonas. Two isolates,Rhodococcussp. LF-13 andRhodococcussp. LF-22, reduced surface tension of culture medium by more than 40 mN m−1when growing on kerosene,n-hexadecane or rapeseed oil. The biosurfactants were produced by resting cells of the twoRhodococcusstrains suggesting the biosynthesis of the biosurfactants was not necessarily associated with their growth on hydrocarbons. [ABSTRACT FROM PUBLISHER]

Spatial variations in composition of marine microbial communities and its causes have largely been disclosed in studies comprising rather large environmental and spatial differences. In the present study, we explored if a moderate but temporally permanent climatic division within a contiguous arctic shelf seafloor was traceable in the diversity patterns of its bacterial and archaeal communities. Soft bottom sediment samples were collected at 10 geographical locations, spanning spatial distances of up to 640 km, transecting the oceanic polar front in the Barents Sea. The northern sampling sites were generally colder, less saline, shallower, and showed higher concentrations of freshly sedimented phytopigments compared to the southern study locations. Sampling sites depicted low variation in relative abundances of taxa at class level, with persistent numerical dominance by lineages of Gamma- and Deltaproteobacteria (57-66% of bacterial sequence reads). The Archaea, which constituted 0.7-1.8% of 16S rRNA gene copy numbers in the sediment, were overwhelmingly (85.8%) affiliated with the Thaumarchaeota. Beta-diversity analyses showed the environmental variations throughout the sampling range to have a stronger impact on the structuring of both the bacterial and archaeal communities than spatial effects. While bacterial communities were significantly influenced by the combined effect of several weakly selective environmental differences, including temperature, archaeal communities appeared to be more uniquely structured by the level of freshly sedimented phytopigments. [ABSTRACT FROM AUTHOR]