Protective effects of culture extracts (CB08035-SCA and CB08035-SYP) from Marinobacter hydrocarbonoclasticus (strain CB08035) against oxidant-induced stress in human colon carcinoma Caco-2 cells.

The present study investigated the effect of culture extracts (CB08035-SCA and CB08035-SYP) from Marinobacter hydrocarbonoclasticus (strain CB08035) on cell viability and the potential protective effects attributed to molecular mechanisms underlying antioxidant response to survive oxidative stress injuries. Caco-2 cells were submitted to oxidative stress by treatment with tert-butyl hydroperoxide (t-BOOH). Both extracts prevented cell damage and enhanced activity of antioxidant defenses (NQO1 and GST activities and GSH levels) reduced by treatment with t-BOOH. Increased ROS and caspase 3/7 activity induced by t-BOOH were dose-dependently prevented when cells were treated with the extracts. CB08035-SCA caused up-regulation of Nrf2, AKT1 and Bcl-2 gene expressions. Moreover, CB08035-SCA and CB08035-SYP treatments reduced significantly Bax, BNIP3, APAF1, ERK1, JNK1, MAPK1, NFκB1, TNFα, IL-6, IL-1ß and HO-1 gene expressions of apoptosis, proinflammation and oxidative stress induced by t-BOOH. CB08035-SCA and CB08035-SYP CPE extracts confer a significant protection against oxidative insults to cells. Our results show that culture extracts CB08035-SCA and CB08035-SYP from M. hydrocarbonoclasticus (strain CB08035) appeared to have antioxidant potential, based on their ability to protect antioxidant enzymes and mRNA gene expressions linked to apoptosis/oxidative pathways. These results suggest that culture extracts CB08035-SCA and CB08035-SYP can be a potential ingredient in the pharmaceutical and cosmeceutical industries.

An induced corrosion inhibition of X80 steel by using marine bacterium Marinobacter salsuginis.

The corrosion behaviour of X80 pipeline steel was studied in a simulated marine environment inoculated with marine bacterium Marinobacter salsuginis. The electrochemical results showed that the increase in linear polarization resistance, charge transfer resistance, and the decrease in corrosion current density of the X80 pipeline steel immersed in the biotic medium indicated its high corrosion resistance compared to those in the abiotic medium. Surface morphological techniques including scanning electron microscopy, confocal laser scanning microscopy and live/dead cells staining were employed to observe the biofilm morphology and bacterial viability after different immersion times. X-ray photoelectron spectroscopy was used to analyse the oxides film formed on the steel surface. The obtained results indicated that the corrosion inhibition efficiency was obviously higher in the biotic medium compared to that in the abiotic medium. The high corrosion resistance of X80 steel in biotic medium was attributed to the formation of biofilm and the development of extracellular polymeric substances (EPS) layer on its surface.

Distribution of dissolved iron and bacteria producing the photoactive siderophore, vibrioferrin, in waters off Southern California and Northern Baja.

Phytoplankton blooms can cause acute effects on marine ecosystems due either to their production of endogenous toxins or to their enormous biomass leading to major impacts on local economies and public health. Despite years of effort, the causes of these Harmful Algal Blooms are still not fully understood. Our hypothesis is that bacteria that produce photoactive siderophores may provide a bioavailable source of iron for phytoplankton which could in turn stimulate algal growth and support bloom dynamics. Here we correlate iron concentrations, phytoplankton cell counts, bacterial cell abundance, and copy numbers for a photoactive siderophore vibrioferrin biosynthesis gene in water samples taken from 2017 cruises in the Gulf of California, and the Pacific Ocean off the coast of northern Baja California as well as during a multiyear sampling at Scripps Pier in San Diego, CA. We find that bacteria producing the photoactive siderophore vibrioferrin, make up a surprisingly high percentage of total bacteria in Pacific/Gulf of California coastal waters (up to 9%). Vibroferrin's unique properties and the widespread prevalence of its bacterial producers suggest that it may contribute significantly to generating bioavailability of iron via photoredox reactions.

Vibrioferrin, an unusual marine siderophore: iron binding, photochemistry, and biological implications.

Vibrioferrin (VF) is a member of the carboxylate class of siderophores originally isolated from Vibrio parahaemolyticus, an enteropathogenic estuarine bacterium often associated with seafood-borne gastroenteritis. Recently we have also isolated this siderophore from several species of Marinobacter, which are closely associated or "symbiotic" with toxic, bloom-forming dinoflagellates such as Gymnodinium catenatum. We have measured the overall metal-ligand binding constant for iron-vibrioferrin (FeVF) as 10(24.02(5)) making vibrioferrin one of the weakest iron chelators of any known marine siderophore. FeVF is also shown to be considerably more sensitive to photolysis under relatively low illumination conditions than other photoactive siderophores leading primarily to a monodecarboxylated photoproduct that has no significant affinity for Fe(III). The consequences that these features have on bacterial-algal interactions with potential importance to understanding the origin and sustenance of harmful algal blooms are discussed.

Vesicles to concentrate iron in low-iron media: an attempt to mimic marine siderophores.

Amphiphilic catechol-type iron chelators were studied with the aim of mimicking the properties of marine bacterial siderophores. The Fe(III) complexation constants and aqueous solution speciation of L(S10), a sulfonated catechol unit that has a C(10) lipophilic carbon chain connected by an amide linkage, were determined by spectrophotometric titration. The calculated value of pFe3+ is 18.1 at pH 7.4. Cryogenic transmission electron microscopy showed that the tris(catecholate) ferric complex formed at physiological pH initially assembles into micelles, in which the catecholate-iron units stay on the exterior of the micelle. The average diameter of these micelles was estimated to be 4.2 nm. The micelles then slowly rearrange into clusters of different sizes, which leads to the formation of unilamellar and bilamellar vesicles. The reorganization processes are comparable to those observed by Butler et al. for the marinobactin siderophores produced by marine bacteria, but in contrast to the marinobactins, vesicles of the Fe3+-L(S10) complex form without an excess of iron relative to ligand concentration. The time-dependent micelle-to-vesicle transition is discussed herein.