Purification and characterization of indochrome type blue pigment produced by Pseudarthrobacter sp. 34LCH1 isolated from Atacama desert.

The interest in and demand for natural dyes has increased significantly in recent years; however, very few natural blue dyes are commercially available, because blue colored compounds in nature are relatively rare. In this study, a blue pigment-producing bacteria from Lake Chungará (Atacama Desert, Chile) was isolated, and its blue pigment was purified and chemically characterized. The pigment-producing strain was identified as Pseudarthrobacter sp. by 16S rRNA gene sequencing. The pigment was separated from the filtered culture medium by column chromatography/solid-phase extraction using different resins (ionic exchange, C-18, size exclusion). The strain produced up to 2.5 g L-1 of blue pigment, which was very soluble in water, partially soluble in methanol and insoluble in other organic solvents. The pigment was analyzed and characterized by analytical HPLC, UV-Vis, FT-IR, and H-NMR, and purified by semi-preparative HPLC. The pigment was non-toxic to brine shrimp (LD50 > 2.3 g L-1) and was stable at pH 6-10 at temperatures below 60 °C. HPLC analysis shows that the pigment is composed of four major blue fractions. The physicochemical properties and structural analysis demonstrate that this pigment belongs to the indochrome isomers, whose properties have yet to have been characterized. The high solubility in water, good stability in neutral and basic pH, and negligible toxicity of the blue pigment make it a good candidate suitable for several industrial and possibly some food applications.

Distribution and growth of Vibrio parahaemolyticus in southern Chilean clams (Venus antiqua) and blue mussels (Mytilus chilensis).

We evaluated the distribution and growth of Vibrio parahaemolyticus in the inland sea of southern Chile, where the world's largest foodborne gastroenteritis outbreak by the pandemic strain O3:K6 occurred in 2005. Intertidal samples of Mytilus chilensis and Venus antiqua were collected around port towns between 41°28'S and 43°07'S, during April to May 2011 and January to March 2012. We used most probable number real-time polymerase chain reaction (MPN-PCR) for enumeration of the tlh, tdh, and trh genes in freshly harvested bivalves and after a controlled postharvest temperature abuse. Pathogenic markers (tdh+ or trh+) were not detected. Total V. parahaemolyticus (tlh+) in freshly harvested samples reached up to 0.38 and 3.66 log MPN/g in 2011 and 2012, respectively, with values close to or above 3 log MPN/g only near Puerto Montt (41°28'S, 72°55'W). Enrichments by temperature abuse (>2 log MPN/g) occurred mainly in the same zone, regardless of the year, suggesting that both natural or anthropogenic exposure to high temperatures were more critical. Lower salinity and higher sea surface temperature in Reloncaví Sound and Reloncaví Estuary were consistent with our observations and allowed confirmation of the existence of a high-risk zone near Puerto Montt. Based on the results, a strategy focused on risk management inside this defined hazard zone is recommended.

Bacteriostatic anti-Vibrio parahaemolyticus activity of Pseudoalteromonas sp. strains DIT09, DIT44 and DIT46 isolated from Southern Chilean intertidal Perumytilus purpuratus.

We characterised the anti-Vibrio parahaemolyticus (anti-V. parahaemolyticus) marine bacteria DIT09, DIT44 and DIT46 isolated from the intertidal mussel Perumytilus purpuratus. The 16S rRNA gene sequences identify a Pseudoalteromonas sp. that form a clade with P. prydzensis and P. mariniglutinosa. The strains produced bacteriostatic anti-V. parahaemolyticus agents during the exponential growth phase, which were also active against V. cholerae and V. anguillarum, but not on other Gram positive and Gram negative bacteria. Bacteriostatic agents could be permeated by analytic ultra-filtration with 3.5 kDa cut-off, partially precipitated with 70 and 90 % ammonium sulphate, but not extracted with ethyl acetate. Reverse-phase HPLC revealed the production of a set of 5-6 active compounds by each strain (elution from 20 to 40 % acetonitrile), with similar but non identical HPLC patterns. Additionally, V. parahaemolyticus was able to progressively overcome the inhibition of antibiotics in trypticase soy agar with Fe(III) 0.5 up to 2 mM, suggesting the involvement of a set of novel siderophore or active molecules targeted at different Fe-siderophore uptake systems. The overall findings suggest that Pseudoalteromonas sp. DIT strains produce a putatively novel class of bacteriostatic and probably amphiphilic anti-Vibrio agents, indicating the need for further studies with chemical purification followed by their structural and functional characterization. Finally, the crude cell-free extracts, as well as the strains incubated at 10(3) and 10(5) c.f.u./mL, did not cause mortality in Artemia franciscana nauplii, suggesting that these bacteria are serious candidates for further probiotic evaluations with shellfish and fish cultures.

Sulphur-cycling bacteria and ciliated protozoans in a Beggiatoaceae mat covering organically enriched sediments beneath a salmon farm in a southern Chilean fjord.

The colourless mat covering organically enriched sediments underlying an intensive salmon farm in Estero Pichicolo, southern Chile, was surveyed by combined 454 PyroTag and conventional Sanger sequencing of 16S/18S ribosomal RNA genes for Bacteria and Eukarya. The mat was dominated by the sulphide-oxidizing bacteria (SOB) Candidatus Isobeggiatoa, Candidatus Parabeggiatoa and Arcobacter. By order of their abundances, sulphate-reducing bacteria (SRB) were represented by diverse deltaproteobacterial Desulfobacteraceae, but also within Desulfobulbaceae, Desulfuromonadaceae and Desulfovibrionaceae. The eukaryotic PyroTags were dominated by polychaetes, copepods and nematodes, however, ciliated protozoans were highly abundant in microscopy observations, and were represented by the genera Condylostoma, Loxophyllum and Peritromus. Finally, the abundant Sulfurimonas/Sulfurovum also suggest the occurrence of zero-valence sulphur oxidation, probably derived from Beggiatoaceae as a result of bacteriovorus infaunal activity or generated as free S(0) by the Arcobacter bacteria. The survey suggests an intense and complex sulphur cycle within the surface of salmon-farm impacted sediments.