Emulsifying Activity and Stability of a Non-Toxic Bioemulsifier Synthesized by Microbacterium sp. MC3B-10

Abstract

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.

<b>Biosurfactants produced by <i>Microbacterium</i> sp., isolated from aquatic macrophytes in hydrocarbon-contaminated area in the Rio Negro, Manaus, Amazonas

“…Camacho-Chab et al (2013) studying the genus Microbacterium isolated from marine environment reported the production of glycoproteins able to emulsify aromatic hydrocarbons and oils. The emulsifier isolated from the marine environment differs from the biosurfactant isolated in this work as showed by the absorption bands obtained by FTIR, probably due to the environment differences.…”

“…Hassanshahian, Giti, and Simone (2011), Kumar, Mamidyala, Sujitha, Muluka, and Akkenapally (2012) and Wongwongsee, Chareanpat, and Pinyakong (2013) reported the formation of emulsifiers for this genus, though they did not appraise the quantity or the type produced. Also Camacho-Chab et al (2013) have isolated bacteria of the genus Microbacterium from marine environments and identified a compound classified as microbatan. However, there are no reports on biosurfactant production by bacteria of this gender in Amazonian freshwater environment, which are contaminated by hydrocarbons.…”

Implications of Extracellular Polymeric Substance Matrices of Microbial Habitats Associated with Coastal Aquaculture Systems

“…MC3B-10 was characterized previously to have surfactant activity against aliphatic hydrocarbons and hinted at a potential metal-binding activity [154]. This EPS was termed microbactan and was extensively characterized [155]. Bioassay-based toxicity testing showed that microbactan is not toxic.…”

Partial Purification and Chemical Characterization of a Bioemulsifier and Its Application in MEOR

“…Although extensive researches have been conducted on variety of aspects of different bioemulsifiers including production, emulsification activity and cell surface hydrophobic activities, however, few analysis of the field application of bioemulsifiers based on the emulsification activity and production were carried out further. The most likely application of bioemulsifier was in MEOR [2,3], which of low requirements toward the emulsifier concentration and purity. Bioemulsifiers played a significant role in extracting the remaining oil from oil reservoirs, which was cost-effective, environmental-friendly, and efficient particularly in the exploitation of oil remained trapped in capillary pores of the formation rock or in areas not swept by the classical or modernenhanced oil recovery (EOR) methods [3].…”

“…The ability to form stabilized o/w or w/o emulsion and keep the condition was the typical feature of these substances, which ensured its potential application in microbial-enhanced oil recovery (MEOR) [2,3]. Plentiful studies about bioemulsifiers nowadays were done which mainly focused on isolation, screening of active strains, and the characteristics of their products [4][5][6][7][8].…”