The Screening Of SACs-Producers And Investigation On BS Produced By Bacillus Sp. SACs11

Surface active compounds (SACs), including biosurfactants (BS) and bioemulsifier (BE), are natural surfactants produced by animals, plants and microbes. Besides possessing the same excellent properties, such as surface activities, thermal and chemical stability, as synthesized surfactants, SACs have superior properties, such as specific physiological functions, and good environmental compatibility. Additionally, some SACs also have antibacterial, antiviral, antitumor effect, as well as immune function. SACs have been widely used in industry, agriculture, environmental protection, medicine and healthcare, and biological treatment and bio-catalysis. Although have received increasing attention, investigation of SACs have been limited in a few common SACs to date.In our research, we aimed to isolate SACs-producing bacteria from contaminated and uncontaminated environments to study the distribution of SACs-producers in these niches, and to disclose the biological functions of SACs in nature. We also aimed to isolate several hypeproducing strains, by a large scale screening, to study the structures and properties of produced SACs, and to exploit novel surfactants with promising potential in applications, to pave the way for industrial production and application of SACs eventually.In this research, we have constructed an effective screening strategy, with which we have isolated 18 SACs-producers from 10 uncontaminated or contaminated sample sites. We grouped these 18 strains into 5 groups, one was Pseudomonas, and the other 4 were Bacillus. Compared with other screened strains, the BS secreted by strain SACs8, SACs11, and SACs 18 showed higher activities, and all the three BS were anionic lipopeptide surfactants.The yield of BS11 produced by strain Bacillus sp. SACs11 could reach 1.133 g/L with CMC value of 10 mg/L. The surface activities of BS11 were decreased slightly after treated by 115℃, while no impact has been found after being treated by high salinity. We have tried to purify crude BS11 with several purification strategies, including silica gel column chromatography. We also evaluated the effectivity of these strategies, which may pave a way for subsequential investigations, such as purification, structural analysis, and biological function studies.