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Fluorescent derivatization of the carboxyls in surfactin peptide rings is an effective way to improve the sensitivity of trace detection of surfactin, but very little is known about the reaction selectivity of surfactin containing multiple carboxyls in derivatization. In this paper, the reaction selectivity in fluorescent derivatization of a surfactin containing two carboxyls in its peptide ring with 1-bromoacetylpyrene and the catalysis role in the reactions were investigated using electrospray ionization mass spectrometry and tandem mass spectrometry. It showed that only one carboxyl was labeled with 1-bromoacetylpyrene in derivatization reactions, and the connection of the Asp residue with 1-bromoacetylpyrene was confirmed. It also showed that triethylamine as a catalyst was connected with surfactin to liberate more nucleophilic groups beneficial to promote the derivatization rate. This would contribute to better understanding the mechanism of derivatization of surfactin and its analogues with 1-bromoacetylpyrene, and with other fluorescent labeling reagents.

Propionate is a common metabolic intermediate occurring in environmental samples including petroleum reservoirs. Available microbial genomes were obtained from the NCBI database and analyzed in silico by hmmscan to check three metabolic pathways of propionate production in petroleum reservoir systems. The succinate pathway was the dominant one while the other two (lactate and 1,2-propanediol pathways) contributed less to the formation of propionate according to the Hidden Markov Model calculation. The mmdA gene encoding methylmalonyl-CoA decarboxylase was used as a biomarker gene to detect the diversity of microbes involved in the propionate formation in Jiangsu oil reservoirs. The mmdA gene clone library showed that microbes affiliated within the genus of Archaeoglobus, Thermococcus, Anaerobaculum, as well as more than ten other genera were the potential microorganisms involved in the production of propionate. Meanwhile, as the biomarker genes involved in the other two propionate-producing pathways, the functional genes of lcdA and pduP were tested with PCR amplification, but no positive results were observed in Jiangsu oil reservoirs.

A highly sensitive and selective high-performance liquid chromatographic (HPLC) method has been developed for the determination of microbial lipopeptides of fluorescent derivatization with 1-bromoacetylpyrene to overcome the limitations of trace detection of lipopeptides in aqueous solutions. The derivatization of lipopeptides with 1-bromoacetylpyrene was conducted at 60°C for 20 min under catalysis of triethylamine. The resulting derivative products were separated by HPLC and determined by a fluorescence detector. Each homolog of lipopeptides in samples was identified by HPLC-MS and the detection limit after derivatization in an aqueous solution was 2.5 μg/mL (S/N = 3). The calibration curve for lipopeptides was linear in the concentration range of 0.250 - 4.00 mg/mL. This method has adequate sensitivity and selectivity for microdetection of lipopeptides in aqueous solutions in mild reaction conditions, which allows this method to be used in the determination of trace lipopeptides in environmental samples and complex samples.

This study aims to explore the effects and advantages of coblation combined with microscopy to treat epiglottis cysts. Ninety patients with epiglottis cysts were randomly assigned to three groups: the first group: marsupialisation + electric coagulation group, n = 30; the second group: marsupialisation + coblation, n = 30; and the third group: marsupialisation + coblation + microsurgery, n = 30. To compare the cure rate, intraoperative bleeding volume, postoperative pain, operation time and postoperative complications were investigated among these three groups. The comparison among three procedures showed a significant difference for intraoperative bleeding volume, operation time and postoperative pain (P < 0.05), whereas no significant difference was observed for cure rate (P > 0.05). These three procedures are effective in treating epiglottis cysts. Microscopic surgery with coblation has the advantages of less bleeding, short procedure duration, less pain and few complications. Thus, microscopic surgery is worthy of clinical application.

A novel bacterial strain designated 9PNM-6(T) was isolated from an abandoned lead-zinc ore mine site in Meizhou, Guangdong Province, China. The isolate was found to be Gram-negative, rod-shaped, orange-pigmented, strictly aerobic, oxidase- and catalase-positive. Growth occurred at 0-4 % NaCl (w/v, optimum, 0 %), at pH 6.0-8.0 (optimum, pH 7.0) and at 15-32 °C (optimum, 28-30 °C). Phylogenetic analysis based on 16S rRNA gene sequence similarities showed that strain 9PNM-6(T) belongs to the genus Sphingomonas, with the highest sequence similarities with Sphingomonas jejuensis NBRC 107775(T) (99.7 %), Sphingomonas koreensis KCTC 2882(T) (95.1 %) and Sphingomonas dokdonesis KCTC 12541(T) (95.1 %). The chemotaxonomic characteristics of strain 9PNM-6(T) were consistent with those of the genus Sphingomonas. The predominant respiratory quinone was identified as ubiquinone Q-10, the major polyamine as sym-homospermidine, and the major cellular fatty acids as C18:1 ω7c, C16:0, C16:1 ω7c and/or C16:1 ω6c and C14:0 2-OH. The major polar lipids are sphingoglycolipid, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatideylcholine, an unidentified phospholipid and four unidentified aminolipids. The genomic DNA G+C content of strain 9PNM-6(T) was determined to be 69.2 ± 0.6 mol%. Based on comparative analyses of morphological, physiological and chemotaxonomic data, and levels of DNA-DNA relatedness values, strain 9PNM-6(T) is considered to represent a novel species of the genus Sphingomonas, for which the name Sphingomonas gimensis sp. nov. (Type strain 9PNM-6(T) = GIMCC 1.655(T) = CGMCC 1.12671(T) = DSM 27569(T)) is proposed.

Biosurfactant-producing microorganisms inhabiting oil reservoirs are of great potential in industrial applications. Yet, till now, the knowledge about the structure and physicochemical property of their metabolites are still limited. The aim of this study was to purify and structurally characterize the biosurfactant from Pseudomonas aeruginosa strain FIN2, a newly isolated strain from an oil reservoir. The purification was conducted by silica gel column chromatography followed by pre-RP HPLC and the structural characterization was carried out by GC-MS combined with MS/MS. The results show that the biosurfactant produced by FIN2 is rhamnolipid in nature and its four main fractions were identified to be Rha-C10-C10(46.1 %), Rha-Rha-C10-C10(20.1 %), Rha-C8-C10 (7.5 %) and Rha-C10-C12:1(5.5 %), respectively. Meanwhile, the rarely reported rhamnolipid congeners containing β-hydroxy fatty acids of C6, C9, C10:1 and C11 were also proved to be present in the rhamnolipid mixture produced. The rhamnolipid mixture exhibited a strong surface activity by lowering the surface tension of distilled water to 28.6 mN/m with a CMC value of 195 mg/l.

Lipopeptide is one of the most important biosurfactants. The content of each isoform of a lipopeptide is crucial to the study of the properties of metabolites as well as the biological and biochemical characters of microbes. However, this information has not been accurately provided by the current analysis method. A new method for the quantitative determination of each isoform in the surfactin family has been established. The surfactin was firstly hydrolyzed in an acid solution at 90°C for 20 h, dried and then treated with bis(trimethylsilyl)trifluoroacetamide at 60°C for 20 min. The derived hydrolysates were then analyzed by GC-MS for a quantitative determination via comparison with working curves made with amino acids. GC-MS analyses show that the nine isoforms with an amount of 4.80 × 10(-7) mol (493 µg) in a 500 µg surfactin sample were detected, in which the mole fractions of surfactin isoforms with different fatty acid chains were 0.32% (n C(12)), 4.89% (iso C(13)), 6.27% (anteiso C(13)), 23.05% (iso C(14)), 8.95% (n C(14)), 17.69% (iso C(15)), 38.69% (anteiso C(15)), 0.07% (iso C(16)), and 0.07% (n C(16)), respectively. This approach can be applied to quantitative analyses for other families of lipopeptides as long as the sequence of amino acid residues in the peptide is determined.