Microbial community of a saline mud volcano at San Biagio‐Belpasso, Mt. Etna (Italy)

Abstract

In San Biagio of Belpasso, approximately 20 km south of Mt. Etna, in the area of contact between volcanic and sedimentary formations, a number of small (3- 60 cm in diameter) active mud eruptions discharge CO2-rich gases, mud and NaCl brines. They can be described as mini-volcanoes owing to their typical conic shapes and continuously bubbling peak craters. Samples were collected from the active peak craters at a depth of 20 cm and DNA was immediately extracted and amplified with universal 16S rRNA gene-specific primers, followed by cloning procedure. A total of 140 bacterial clones obtained were screened and clustered by restriction fragment length polymorphism (RFLP) analysis. The pool of 16S rRNA sequences representing each RFLP cluster was subjected to phylogenetic analysis. All of the 33 sequences analysed were affiliated with the kingdom of Eubacteria; 28 sequences (77% of all clones) affiliated with the Proteobacteria, two sequences (19% of all clones) were affiliated with Actinobacteria and three sequences (4% of all clones) were affiliated with the Flexibacter-Cytophaga-Bacteroides division. The data obtained suggest that the microorganisms phylogenetically affiliated to autotrophic methane oxidizers and heterotrophic hydrocarbon degraders belonging to the gamma-subclass of Proteobacteria are major constituents of the microbial communities of the saline volcanic muds. Overall, the composition of the microbial community of the San Biagio mud volcano resembles the compositions of marine microbial communities, which might indicate that wind-blown seawater vapour acted as an inoculum for microbial community described in present work.

Obligate oil-degrading marine bacteria

“…Nr. DQ337077; [28]), hydrocarbon-polluted saline soil ( [29]) and various geothermal areas in Italy and USA (Yellowstone) [30,31] (Figure 2). This ubiquity of A. borkumensis is presumably due to its capacity to grow on many saturated petroleum fraction constituents and on biogenic hydrocarbons: straight-chain and branched alkanes, isoprenoids, and long-side-chain alkyl compounds, including alkylmonocycloalkanes, alkylbenzenes, and organic alkyl-sulfuric compounds [32,33].…”

Characteristic features of Bacillus cereus cell surfaces with biosorption of Pb(II) ions by AFM and FT-IR

“…Bacteria are ubiquitous in a wide range of geologic environments, from surface waters, groundwater aquifers and soil systems, to mid-ocean hydrothermal vents, deep sedimentary basins and geothermal hot springs [1][2][3][4][5][6]. In the water-rock systems, bacteria can conduct adsorption reaction due to their extremely high surface area to volume rate and the presence of specific cell wall functional groups [4][5][6][7][8].…”

Directed evolution can rapidly improve the activity of chimeric assembly-line enzymes

“…The modular organization of protein domains in NRPSs has stimulated efforts to swap genes encoding heterologous domains into NRPSs with the goal of producing nonnatural variants of the original small-molecule product (3,4). Although limited success has been achieved with the production of nonribosomal peptide (NRP) variants (5)(6)(7)(8)(9)(10)(11)(12)(13)(14), the resultant chimeric NRPSs are usually nonfunctional or heavily impaired, often yielding too little of the new product to make production feasible. It is not yet known why chimeric NRPSs suffer large reductions in activity, although it is likely that domain swapping disrupts quaternary interactions between protein domains in the assembly line (15).…”