Antibiotic resistance has become one of the world’s most severe problems because of the overuse of antibiotics. Antibiotic-resistant bacteria are more difficult to kill and more expensive to treat. Researchers have been studied on antibiotic alternatives such as antimicrobial peptides and lipopeptides. A bacteriostatic functional bacteria MB01 producing lipopeptides was isolated from the Bohai Sea sediments, which had been identified as Bacillus licheniformis by the morphological, physiological and biochemical identification and 16s rDNA sequence. The lipopeptides produced by MB01 were determined to be cyclic surfactin homologs by LC-ESI-MS structural identification after crude extraction and LH-20 chromatography. [M+H]+ m/z 994, 1008, 1022, 1036 were all the characteristic molecular weight of surfactin homologs. CID analysis revealed that the molecular structure of the lipopeptides was Rn-Glu1-Leu/Ile2-Leu3-Val4-Asp5-Leu6-Leu/Ile7. The lipopeptides showed well resistance to UV light and the change of pH and temperature.

A biosurfactant-producing bacterium, designated 3B-2, was isolated from marine sediment and identified as Vibrio sp. by 16S rRNA gene sequencing. The culture medium composition was optimized to increase the capability of 3B-2 for producing biosurfactant. The produced biosurfactant was characterized in terms of protein concentration, surface tension and oil-displacement efficiency. The optimal medium for biosurfactant production contained: 0.5% lactose, 1.1% yeast extract, 2% sodium chloride and 0.1% disodium hydrogen phosphate. Under optimal conditions (28°C), the surface tension of crude biosurfactant could be reduced to 41 from 71.5 mN/m (water), while its protein concentration was increased to up to 6.5 g/L and the oil displacement efficiency was improved dramatically at 6.5 cm. Two glycoprotein fractions with the molecular masses of 22 and 40 kDa were purified from the biosurfactant, which held great potential for applications in microbial enhanced oil recovery and bioremediation.

Crude oil is a complex mixture of hydrocarbons with different structures; its components vary in bioavailability and toxicity. It is important to understand how bacterial communities response to different hydrocarbons and their co-acclimation in the process of degradation. In this study, microcosms with the addition of structurally different hydrocarbons were setup to investigate the successions of bacterial communities and the interactions between different bacterial taxa. Hydrocarbons were effectively degraded in all microcosms after 40 days. High-throughput sequencing offered a great quantity of data for analyzing successions of bacterial communities. The results indicated that the bacterial communities responded dramatically different to various hydrocarbons. KEGG database and PICRUSt were applied to predict functions of individual bacterial taxa and networks were constructed to analyze co-acclimations between functional bacterial groups. Almost all functional genes catalyzing degradation of different hydrocarbons were predicted in bacterial communities. Most of bacterial taxa were believed to conduct biodegradation processes via interactions with each other. This study addressed a few investigated area of bacterial community responses to structurally different organic pollutants and their co-acclimation and interactions in the process of biodegradation. The study could provide useful information to guide the bioremediation of crude oil pollution.