Identification of a Shewanella halifaxensis Strain with Algicidal Effects on Red Tide Dinoflagellate Prorocentrum triestinum in Culture.

The dinoflagellate Prorocentrum triestinum forms high biomass blooms that discolor the water (red tides), which may pose a serious threat to marine fauna and aquaculture exploitations. In this study, the algicidal effect of a bacterial strain (0YLH) belonging to the genus Shewanella was identified and evaluated against P. triestinum. The algicidal effects on the dinoflagellate were observed when P. triestinum was exposed to cell-free supernatant (CFS) from stationary-phase cultures of the 0YLH strain. After 24 h exposure, a remarkable reduction in the photosynthetic efficiency of P. triestinum was achieved (55.9%), suggesting the presence of extracellular bioactive compounds produced by the bacteria with algicidal activity. Furthermore, the CFS exhibited stability and maintained its activity across a wide range of temperatures (20-120 °C) and pH values (3-11). These findings highlight the algicidal potential of the bacterium Shewanella halifaxensis 0YLH as a promising tool for the environmentally friendly biological control of P. triestinum blooms.

A plant from the altiplano of Northern Chile Senecio nutans, inhibits the Vibrio cholerae pathogen.

BACKGROUND: In the altiplano of Northern Chile the plant Senecio nutans is habitually used as an infusion to relieve the effects of altitude sickness (locally known as "puna"). It is also used to alleviate the bronchitis, whooping cough, asthma, stomachache, tiredness and fever. The extreme conditions under which these plant grow and scientific data that shows the inhibiting potential of the essential oils of plants of the genus Senecio represents great potential in the study of their application to control pathogens like Vibrio Cholera. METHODS: The essential oil from aerial parts of S. nutans was isolated by hydrodistillation and the chemical composition characterized by GC-MS analyses. The antibacterial potential and determination of MIC value, was estimated in both micro and macro dilution method. RESULTS: The GC-MS analysis of essential oil of S. nutans showed the presence of methyl cinnamate (44.9 %), p-cymenol (27.2 %), and terpinen-4-ol (6.8 %), α-terpineol (4.1 %), t-cadinol (3.5 %), methyl hydrocinnamate (2.1 %), δ-cadinene (2.0 %), p-cymene (1.9 %), γ-terpinene (1.8 %), α-cadinol (1.6 %), cis-sabinene hydrate (1.1 %), caryophyllene (0.9 %), ß-pinene (0.8 %), and α-terpinene (0.6 %) as major components. Moreover, the oil of S. nutans exhibited an important antibacterial activity with a diameter of inhibition zone growth of 22 mm and the MIC value of 0.4 mg/mL against pathogenic bacteria V. cholerae. CONCLUSIONS: The results show for the first time the antibacterial activity of the essential oils of S. nutans against the V. cholerae pathogen, an activity that can be applied as a preventive treatment against the action of pathogen.

Oleic acid produced by a marine Vibrio spp. acts as an anti-Vibrio parahaemolyticus agent.

It is known that some strains of Vibrio parahaemolyticus are responsible for gastroenteric diseases caused by the ingestion of marine organisms contaminated with these bacterial strains. Organic products that show inhibitory activity on the growth of the pathogenic V. parahaemolyticus were extracted from a Vibrio native in the north of Chile. The inhibitory organic products were isolated by reverse phase chromatography and permeation by Sephadex LH20, and were characterized by spectroscopic and spectrometric techniques. The results showed that the prevailing active product is oleic acid, which was compared with standards by gas chromatography and high-performance liquid chromatography (HPLC). These active products might be useful for controlling the proliferation of pathogenic clones of V. parahaemolyticus.

Marine Bacillus spp. associated with the egg capsule of Concholepas concholepas (common name "loco") have an inhibitory activity toward the pathogen Vibrio parahaemolyticus.

The pandemic bacterium Vibrio parahaemolyticus, isolated from seawater, sediment, and marine organisms, is responsible for gastroenteric illnesses in humans and also cause diseases in aquaculture industry in Chile and other countries around the world. In this study, bacterial flora with inhibitory activity against pathogenic V. parahaemolyticus were collected from egg capsules of Concholepas concholepas and evaluated. The 16S rRNA fragment was sequenced from each isolated strain to determine its identity using the GenBank database. A phylogenetic analysis was made, and tests for the productions of antibacterial substance were performed using the double-layer method. Forty-five morphotypes of bacterial colonies were isolated, 8 of which presented an inhibitory effect on the growth of V. parahaemolyticus. 16S rRNA sequence and phylogenetic analysis show that these strains constitute taxa that are phylogenetically related to the Bacillus genus and are probably sister species or strains of the species Bacillus pumilus, Bacillus licheniform, or Bacillus sp. It is important to determine the nature of the antibacterial substance to evaluate their potential for use against the pathogen species V. parahaemolyticus.