Mode of Long-chain Alkane Uptake by a Pseudomonas aeruginosa / 微生物学通报

The mode of long-chain alkane uptake by Pseudomonas aeruginosa (CGMCC 1.1785) was studied. P. aeruginosa 1.1785 is capable of using solid long-chain alkane as sole carbon source and producing surface active compound as metabolite. The mass transfer limitation in uptake of alkane was confirmed from the observation that interfacial area of eicosane with water dominates the growth rate of this strain. The enhancement of eicosane uptake by rhamnolipid was mainly caused by increase of interfacial area, since the pseudosolubilized alkane can not support the growth of P. aeruginosa 1.1785. Cell surface hydrophobicity was increased dramatically at the initial phase of growth and followed by a gradual decrease, which indicates that different modes are employed by P. aeruginosa 1.1785 at different growth phase. Therefore, the surfactant mediated mode can be negligible in the uptake process, while the directly attachment mode may not work throughout the growth of P. aeruginosa 1.1785. We proposed a novel uptake mode, in which the chemotaxis of this strain plays an important role.

Advance in Mechanism of Alkane Uptake by Microorganism / 微生物学通报

Recent advance in researches of alkane uptake by microorganisms was reviewed. To improve efficiency of bioremediation, knowledge of mechanism of water-insoluble substrate, especially alkanes, uptake by microorganism is badly needed. Powered by novel ideas and advanced techniques, more findings and conclusions were reported. Effects of surfactants on uptake of alkane, adjustment on cell surface properties and transport of alkane into the cells were discussed in this review, at the same time, evidences from analyses of cell ultra-structure and researches on cell chemotaxis were cited. There are still some questions in this area should be taken into consideration.

Isolation and Identification of a Lipopeptide / 微生物学通报

A lipopeptide compound was isolated from the culture of Bacillus subtilis HSO121 by methods of acidic precipitation, solvent extract, fractional precipitation, adsorption and prepared thin-layer chromatography; and its molecular structure was determined by by ninhydrin assay and IR methods following the Amino analysis, MS-MS and ESI-MS. It shows that the isolated lipopeptide consists of two homologues with molecular mass 1,022D and 1,036D and bearing a cyclic structure with the amino acid sequence Leu-Leu-Asp-Val-Leu-Leu-Glu in the peptide chain, which indicates that the isolated lipopeptide falls into the analogs of surfactin.