Characterization of the extracellular biodemulsifier of Bacillus mojavensis XH1 and the enhancement of demulsifying efficiency by optimization of the production medium composition

Demulsification techniques of water-in-oil and oil-in-water emulsions in petroleum industry

“…In contrast, reports on production of biodemulsifiers from hydrophilic carbon sources have rarely been presented, except for the production of the extracellular biodemulsifier, acetoin, by Bacillus Subtilis grown on glucose, applied for the separation of a model O/W emulsion system [167]. However, combined hydrophilic and hydrophobic carbon sources have also been introduced, such as utilization of glucose along with liquid paraffin for the synthesis of extracellular biodemulsifier from demulsifying strain Bacillus mojavensis XH1, where glucose took part in the demulsifier biosynthesis, and liquid paraffin enhanced the lipophilicity as well as sprinkle of biosurfactant [168]. Liu et al [165] experimentally concluded the following assertions by comparing several hydrophobic carbon sources with various hydrophilic substrates for the production of a biodemulsifier from Alcaligenes sp.…”

“…Neutral (pH = 7.0) or near-neutral environment has often been reported for the production of various biodemulsifiers [168,169,[171][172][173][174]. Amirabadi et al [173] recognized that maximum production of biodemulsifier from Paenibacillus alvei ARN63 was obtained at medium pH = 7.0, and pH values larger than 7.0 were unable to provide an appropriate condition for biodemulsifier production.…”

“…On the other hand, Li et al [168] viewed that the extracellular biodemulsifier of Bacillus mojavensis XH1 maintained a high demulsifying ratio when exposed to temperatures below 75 °C, but its demulsifying ratio at higher temperatures (from 75 °C to 120 °C) was drastically declined to a value less than half that obtained before further increase of temperature. Moreover, biodemulsifiers usually respond in a different manner from one another when undergo a harsh thermal treatment, depending on their tolerance or stability against variations of temperature.…”

“…Demulsification ability in cellular biodemulsifying agents, such as those produced by Nocardia [144], Corynebacterium [145,182], Micrococcus [152], Rhodococcus [179], Ochrobactrum anthropi [181], Alcaligenes [171], and hybrid bacteria [159,163], resides in the bacterial cell surface, whereas demulsifying capability in extracellular biodemulsifiers, including acetoin [167], fengycin [173], protein and lipopeptide [168], and fatty acids and carbohydrates [178], is present in their culture supernatant. Cellular demulsifiers have been found more promising than extracellular ones for demulsification of emulsions, due to possession of more intricate demulsification mechanism [160].…”

Demulsification capabilities of a Microbacterium species for breaking water-in-crude oil emulsions

“…So far, microbial demulsifiers have been commonly produced by pure cultures such as Alcaligenes sp., Corynebacterium petrophilum, Nocardia amarae, Rhodococcus aurantiacus, Mycobacterium sp., Bacillus subtilis, Torulopsis bombicola, Acinetobacter calcoaceticus, Arthrobacter sp., Micrococcus sp. (Carins et al, 1982;Cooper et al, 1982;Stewart et al, 1983;Das et al, 2001;Huang et al, 2009;Wen et al, 2010;Li et al, 2012, Long et al, 2012, and mixed bacterial culture (Kosaric and Duvanjak, 1987;Nadarajah et al, 2002) Bottom sediment and water.…”