A previously reported bacterial bioemulsifier, here termed microbactan, was further analyzed to characterize its lipid component, molecular weight, ionic character and toxicity, along with its bioemulsifying potential for hydrophobic substrates at a range of temperatures, salinities and pH values. Analyses showed that microbactan is a high molecular weight (700 kDa), non-ionic molecule. Gas chromatography of the lipid fraction revealed the presence of palmitic, stearic, and oleic acids; thus microbactan may be considered a glycolipoprotein. Microbactan emulsified aromatic hydrocarbons and oils to various extents; the highest emulsification index was recorded against motor oil (96%). The stability of the microbactan-motor oil emulsion model reached its highest level (94%) at 50 °C, pH 10 and 3.5% NaCl content. It was not toxic to Artemia salina nauplii. OPEN ACCESS Int. J. Mol. Sci. 2013, 14 18960Microbactan is, therefore, a non-toxic and non-ionic bioemulsifier of high molecular weight with affinity for a range of oily substrates. Comparative phylogenetic assessment of the 16S rDNA gene of Microbacterium sp. MC3B-10 with genes derived from other marine Microbacterium species suggested that this genus is well represented in coastal zones. The chemical nature and stability of the bioemulsifier suggest its potential application in bioremediation of marine environments and in cosmetics.

The excessive use of fertilizers in agriculture is mainly due to the recognized plant requirements for soluble phosphorus. This problem has limited the implementation of sustainable agriculture. A viable alternative is to use phosphate solubilizing soil microorganisms. This work aimed to isolate inorganic phosphorus-solubilizing bacteria from the soils of agroecosystems, to select and identify, based on sequencing and phylogenetic analysis of the 16S rRNA gene, the bacterium with the highest capacity for in vitro solubilization of inorganic phosphate. Additionally, we aimed to determine its primary phosphate solubilizing mechanisms and to evaluate its effect on Habanero pepper seedlings growth. A total of 21 bacterial strains were isolated by their activity on Pikovskaya agar. Of these, strain ITCB-09 exhibited the highest ability to solubilize inorganic phosphate (865.98 µg/mL) through the production of organic acids. This strain produced extracellular polymeric substances and siderophores that have ecological implications for phosphate solubilization. 16S rRNA gene sequence analysis revealed that strain ITCB-09 belongs to the genus Enterobacter. Enterobacter sp. ITCB-09, especially when immobilized in beads, had a positive effect on Capsicum chinense Jacq. seedling growth, indicating its potential as a biofertilizer.

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Nanoparticles (NPs) of metal oxides, sometimes referred to as engineered nanoparticles have been used to protect building surfaces against biofilm formation for many years, but their history in the Cultural Heritage world is rather short. Their first reported use was in 2010. Thereafter, a wealth of reports can be found in the literature, with Ti, Ag and Zn oxides being the major protagonists. As with all surface treatments, NPs can be leached into the surrounding environment, leading to potential ecotoxicity in soil and water and associated biota. Dissolution into metal ions is usually stated to be the main mode of toxic action and the toxic effects, when determined in the marine environment, decrease in the order Au > Zn > Ag > Cu > Ti > C 60 , but direct action of NPs cannot be ruled out. Although ecotoxicity has been assessed by a variety of techniques, it is important that a suitable standard test be developed and the European Unions's Biocidal Product Registration group is working on this, as well as a standard test for antimicrobial efficacy to determine their impact on ecological processes of surrounding non-target organisms and their transformation products under realistic scenarios.