The methanogenic alkanes-degrading enrichment culture which had been incubated for over 1,300 days amended with n-alkanes (C15–C20) was investigated through clone libraries of bacteria, archaea and assA, mcrA functional genes. These enrichment cultures were obtained from oily sludge after an initial incubation of the oily sludge without any carbon source and then an enrichment transfer with n-alkanes (C15–C20) for acclimation. Activation of alkanes, methane precursor generation and methanogenic pathways are considered as three pivotal stages for the continuous methanogenesis from degradation of alkanes. The presence of functional genes encoding the alkylsuccinate synthase α-subunit indicated that fumarate addition is most likely the one of initial activation step for degradation of n-alkanes. Degradation intermediates of n-alkanes were octadecanoate, hexadecanoate, butyrate, isobutyrate, acetate and propionate, which could provide the appropriate substrates for acetate formation. Both methyl coenzyme M reductase gene and 16S rRNA gene analysis showed that microorganisms of Methanoseata were the most dominant methanogens, capable of using acetate as the electron donor to produce methane. Bacterial clone libraries showed organisms of Anaerolineaceae (within the phylum of Chloroflexi) were predominant (45.5%), indicating syntrophically cooperation with Methanosaeta archaea was likely involved in the process of methanogenic degradation of alkanes. Alkanes may initially be activated via fumarate addition and degraded to fatty acids, then converted to acetate, which was further converted to methane and carbon dioxide by methanogens.

Lipopeptides produced by microorganisms are one of the five major classes of biosurfactants known and they have received much attention from scientific and industrial communities due to their powerful interfacial and biological activities as well as environmentally friendly characteristics. Microbially produced lipopeptides are a series of chemical structural analogues of different families and, among them, 26 families covering about 90 lipopeptide compounds have been reported in the last two decades. This paper reviews the chemical structural characteristics and molecular behaviors of surfactin, one of the representative lipopeptides of the 26 families. In particular, two novel surfactin molecules isolated from cell-free cultures of Bacillus subtilis HSO121 are presented. Surfactins exhibit strong self-assembly ability to form sphere-like micelles and larger aggregates at very low concentrations. The amphipathic and surface properties of surfactins are related to the existence of the minor polar and major hydrophobic domains in the three 3-D conformations. In addition, the application potential of surfactin in bioremediation of oil spills and oil contaminants, and microbial enhanced oil recovery are discussed.

The lipopeptide produced by microorganisms is one of the representative biosurfactants and is characterized as a series of structural analogues of different families. Thirty-four families covering about 300 lipopeptide compounds have been reported in the last decades, and most of the reported lipopeptides produced by microorganisms were under aerobic conditions. The lipopeptide-producing strains under anaerobic conditions have attracted much attention from both the academic and industrial communities, due to the needs and the challenge of their applications in anaerobic environments, such as in oil reservoirs and in microbial enhanced oil recovery (MEOR). In this review, the fifty-eight reported bacterial strains, mostly isolated from oil reservoirs and dominated by the species Bacillus subtilis, producing lipopeptide biosurfactants, and the species Pseudomonas aeruginosa, producing glycolipid biosurfactants under anaerobic conditions were summarized. The metabolic pathway and the non-ribosomal peptide synthetases (NRPSs) of the strain Bacillus subtilis under anaerobic conditions were analyzed, which is expected to better understand the key mechanisms of the growth and production of lipopeptide biosurfactants of such kind of bacteria under anaerobic conditions, and to expand the industrial application of anaerobic biosurfactant-producing bacteria.

Lithium-brine is an important potential source of lithium. Much research and investigation has been carried out aimed at lithium recovery from brine. Although the distribution and occurrence status of lithium in brine have important implications for lithium recovery, few reports had correlated to this issue. In this article, a study was carried out to explore the lithium migration behavior during brine evaporation and KCl production process at Qarhan Salt Lake. The occurrence status of lithium both in fresh mined brine and residual brine after evaporation were also speculated by means of lithium concentration evaluation and theoretical calculation based on the Pitzer electrolyte solution theory. Results showed that, for Qarhan brine mined from the Bieletan region, most lithium was enriched in the residual brine during the brine evaporation process. The concentration of lithium in the residual brine could be more than 400 mg/L. More than 99.93% lithium ions in residual brine exist in free ions state and lithium does not precipitate from brine with a density of 1.3649 g/mL. The results also revealed that lithium concentration in wastewater discharged from KCl plants can reach a level of 243.8 mg/L. The investigation results provide a theoretical basis for comprehensive development and utilization of lithium resources in Qarhan Salt Lake.