Anaerobic degradation of alkanes in hydrocarbon-rich environments has been documented
and different degradation strategies proposed, of which the most encountered one is
fumarate addition mechanism, generating alkylsuccinates as specific biomarkers.
However, little is known about the mechanisms of anaerobic degradation of alkanes in
oil reservoirs, due to low concentrations of signature metabolites and lack of mass
spectral characteristics to allow identification. In this work, we used a
multidisciplinary approach combining metabolite profiling and selective gene assays
to establish the biodegradation mechanism of alkanes in oil reservoirs. A total of
twelve production fluids from three different oil reservoirs were collected and
treated with alkali; organic acids were extracted, derivatized with ethanol to form
ethyl esters and determined using GC-MS analysis. Collectively, signature metabolite
alkylsuccinates of parent compounds from C1 to C8 together with their (putative)
downstream metabolites were detected from these samples. Additionally, metabolites
indicative of the anaerobic degradation of mono- and poly-aromatic hydrocarbons
(2-benzylsuccinate, naphthoate, 5,6,7,8-tetrahydro-naphthoate) were also observed.
The detection of alkylsuccinates and genes encoding for alkylsuccinate synthase
shows that anaerobic degradation of alkanes via fumarate addition occurs in oil
reservoirs. This work provides strong evidence on the in situ anaerobic
biodegradation mechanisms of hydrocarbons by fumarate addition.
Developing eco‐friendly, nonirritant, low‐toxic, and high‐efficient surface active ingredients for detergents is an ongoing challenge in the detergent field. Surfactin is one of the representative lipopeptides produced by microorganisms. In this article, we report the surfactin isolated from cell‐free broth of Bacillus subtilis HSO121 and purified by reversed‐phase high‐performance liquid chromatography for detergent formulations. The biodegradability, acute dermal irritation, acute oral toxicity (LD50 and LC50), surface activity, washing efficiency, and compatibility with hard water of the purified biosurfactant surfactin have been studied to explore the feasibility for applications of the surfactin in detergents. Acute oral toxicity tests (LD50 > 5000 mg kg−1, LC50 > 1000 mg kg−1) and skin irritation tests (PII = 0) indicate that the surfactin is a low‐toxic and nonirritant ingredient for detergent formulation. Moreover, the surfactin shows excellent surface and interfacial properties of emulsification and wettability, high compatibility, and stability in a wide range of temperatures, pH, and hard water and acceptable properties in biodegradability and foaming ability, which suggests that the biosurfactant surfactin is a promising ingredient for detergent formations in our daily life and for industrial applications.
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