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Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biosurfactants are a group of amphiphilic compounds biosynthesized by different animals, plants, and microbial-based resources. They possess surface-active properties such as emulsification, molecular self-assembly, and the reduction of surface/interfacial tension. This review aims to summarize green manufacturing of biosurfactants via bio-wastes valorization. Several environmental/nutritional factors influencing the production of biosurfactants (e.g., carbon sources, nitrogen sources, temperature, pH, and salts concentration) have been described. The superior physicochemical properties of biosurfactants make them interesting candidates for broad-scale applications, including bioremediation of hydrocarbons/heavy metals, agricultural formulations, and microbial enhanced oil recovery (MEOR). Over the previous decade, research on biosurfactants has substantially increased due to their environmentally friendly behavior and production capability using low-cost waste biomasses "green technology". However, the industrial-scale synthesis of biosurfactants faces several challenges that need to be addressed before considering commercialization. Herein, existing challenges and possibilities in bioprocessing applications of biosurfactants have been summarized to suggest future research recommendations. Tailored production of biosurfactants can broaden their scope for practical applications to realize the sustainable and circular bioeconomy. [Display omitted] • Green manufacturing of biosurfactants via bio-wastes valorization has become an important R&D frontier. • The superior features of microbial surfactants in different industrial applications have been summarized in detail. • Potential challenges in the circular economy of microbial biosurfactant with possible solutions and research directions. [ABSTRACT FROM AUTHOR]

In order to research oil displacement mechanism by indigenous microbial communities under reservoir conditions, indigenous microbial flooding experiments using the endogenous mixed bacterium from Shengli Oilfield were carried out. Through microscopic simulation visual model, observation and analysis of distribution and flow of the remaining oil in the process of water flooding and microbial oil displacement were conducted under high temperature and high pressure conditions. Research has shown that compared with atmospheric conditions, the growth of the microorganism metabolism and attenuation is slowly under high pressure conditions, and the existence of the porous medium for microbial provides good adhesion, also makes its growth cycle extension. The microbial activities can effectively launch all kinds of residual oil, and can together with metabolites, enter the blind holes off which water flooding, polymer flooding and gas flooding can’t sweep, then swap out remaining oil, increase liquidity of the crude oil and remarkably improve oil displacement effect. [ABSTRACT FROM AUTHOR]

Microbial enhancing coal-bed methane generation (MECMG) is a feasible and environment-friendly approach for improving coal-bed methane production. In order to understand the potential of biogenic methane generation and factors controlling the process, the biogenic methane yield, coal intrinsic characteristics and incubation conditions are assembled from the published data. Results show that sub-bituminous and high volatile C-B bituminous coal have higher biogenic methane generation yield than that in peat and anthracite. Contents of H, N, and volatile matter in the coal contribute positively to the biogenic methane generation yield. The optimized conditions for ex-situ biogenic methane generation are headspace gas type, culture temperature, particle size, solid-liquid ratio and pH of N 2 :CO 2 (4:1 v/v), 28–30 °C, 60 μm, 1:10, and 7.0–7.5, respectively. The organic composition and molecular structure collected from coal-bed produced water, culture solution, and biodegraded residuals would provide effective evidences for revealing biogenic methane generation mechanisms. [ABSTRACT FROM AUTHOR]

In this study, the bacterium Bacillus licheniformis DSM = 13 strain ATCC 14580 and the yeast Candida albicans IMRU 3669 were used for biosurfactant production. Surface properties of the produced biosurfactants were confirmed by determining the emulsification power as well as surface tension. The crude biosurfactants have been extracted from supernatant culture growth. FTIR analysis confirmed the chemical structure of the produced biosurfactants. The yields of crude biosurfactants were about 1 and 12 g/l for B. licheniformis and C. albicans respectively. Also, the results revealed that the emulsification power has been increased up to 96% and 65% with kerosene for bacterial and yeast strain respectively. Surface tension decreased from 72 to 36 mN/m after 72 h of incubation with B. licheniformis and 45 mN/m after 4 days of incubation with C. albicans . The potential application of this bacterial species in microbial enhanced oil recovery (MEOR) was investigated. The percent of oil recovery were 16.6 and 8.6 wt% for the bacterial and yeast strains respectively, upon application in sand pack column designed to stimulate an oil recovery. [ABSTRACT FROM AUTHOR]

Abstract To improve the production effect of oil-water transitional zone in thin-shallow extra heavy oil reservoirs of Chunfeng Oilfield in western marginal area of the Junggar Basin, microbial enhanced oil recovery was studied taking the P6-P48 well of the oil-water transitional zone as an example. In the early stage of steam stimulation, the P6-P48 well was shut-in due to high water cut caused by edge water incursion, and analysis showed that its reservoir conditions are suitable for microbial cold production technology. According to the P6-P48 well oil sample composition, the study screened indigenous microbe strain of bacillus XJ2-1, aeruginosa XJ3-1, Dietz's bacteria Z4M8-2, inoculating microbes strain of bacillus SLG5B10-17, nutrient solution, and activator; and designed microbial injection scheme according to near borehole zones treatment radius. In September 2014, 865 m3 of microbial bacterial liquid, nutrient solution and activator was injected and the well was shut in for 166 d of reaction time. The well-hole was opened to produce in March 15, 2015, and has produced 405 d until April 30, 2016, producing oil 3 464 t. The 50 °C degassing crude oil viscosity was decreased by 58% after microbial enhanced oil recovery, and the injected live bacteria was found in produced fluid, with more quantity, indicating that the injected bacteria are adaptive and has reproduced in formation condition. Compared with 16 adjacent wells of steam soaking, microbial enhanced oil recovery has long valid period and better economic benefit. Microbial enhanced oil recovery also got good results in the P6-P49 and P6-P47 wells. [ABSTRACT FROM AUTHOR]

Biosurfactant-facilitated oil recovery is one of the most important aspects of microbial enhanced oil recovery (MEOR). However, the biosurfactant production by biosurfactant-producing microorganisms, most of which are aerobes, is severely suppressed due to the insitu anoxic conditions within oil reservoirs. In this research, we successfully engineered a strain JD-3, which could grow rapidly and produce lipopeptide under anoxic conditions, by protoplast confusion using a Bacillus amyloliquefaciens strain BQ-2 which produces biosurfactant aerobically, and a facultative anaerobic Pseudomonas stutzeri strain DQ-1 as parent strains. The alignment of 16S rDNA sequence (99% similarity) and comparisons of cell colony morphology showed that fusant JD-3 was closer to the parental strain B. amyloliquefaciens BQ-2. The surface tension of culture broth of fusant JD-3, after 36-hour cultivation under anaerobic conditions, decreased from initially 63.0 to 32.5 mN·m-1. The results of thin layer chromatography and infrared spectrum analysis demonstrated that the biosurfactant produced by JD-3 was lipopeptide. The surface-active lipopeptide had a low critical micelle concentration (CMC) of 90 mg·L-1 and presented a good ability to emulsify various hydrocarbons such as crude oil, liquid paraffin, and kerosene. Strain JD-3 could utilize peptone as nitrogen source and sucrose, glucose, glycerin or other common organics as carbon sources for anaerobic lipopeptide synthesis. The subculture of fusant JD-3 showed a stable lipopeptide-producing ability even after ten serial passages. All these results indicated that fusant JD-3 holds a great potential to microbially enhance oil recovery under anoxic conditions. [ABSTRACT FROM AUTHOR]

In this study, the bacterium Bacillus licheniformis has been isolated from oil reservoir; the ability of this bacterium to produce a biosurfactant was detected. Surface properties of the produced biosurfactant were confirmed by determining the emulsification power as well as surface and interfacial tension. The crude biosurfactant has been extracted from supernatant culture growth, and the yield of crude biosurfactant was about 1 g/l. Also, chemical structure of the produced biosurfactant was confirmed using FTIR analysis. Results revealed that, the emulsification power has been increased up to 96% and the surface tension decreased from 72 of distilled water to 36 mN/m after 72 h of incubation. The potential application of this bacterial species in microbial-enhanced oil recovery (MEOR) was investigated. The percent of oil recovery was 16.6% upon application in a sand pack column designed to stimulate an oil recovery. It also showed antimicrobial activity against the growth of different strains of SRB (sulfate reducing bacteria). Results revealed that a complete inhibition of SRB growth using 1.0% crude biosurfactant is achieved after 3 h. [ABSTRACT FROM AUTHOR]

Abstract: Microbial enhanced oil recovery (MEOR) is one of the potential methods for extending the life of declining reservoir. Microbial consortia from Al-Wusta region, Sultanate of Oman were studied using culture dependant and independent methods. Microbial consortia from formation water samples were isolated using enrichment culture and identified using denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene sequencing. Different microbial consortia were detected from oil wells and water collection and redistribution station. A total of 33 genera and 58 species were identified and all the identified microbes were first report in Omani oil fields. Most of those identified microorganisms were found to be anaerobic, thermophilic and halophilic, which have been reported as favourable candidates for in-situ MEOR applications. [Copyright &y& Elsevier]

The article presents a study regarding the optimization and partial characterization of biosurfactants produced by Bacillus species. The study examines the potential of microbial enhanced oil recovery (MEOR) as an effective alternative in Omani oil fields. It revealed that the bacteria has high potential when used during ex-situ MEOR applications, wherein 23 percent of residual oil was produced.

Abstract: The effectiveness of CO2 geological storage depends on a combination of physical and geochemical trapping mechanisms. Over time, the physical process of residual CO2 trapping and geochemical processes of solubility trapping and mineral trapping increase. According to the IPCC special report, mineral trapping is believed to be comparatively slow, potentially taking a thousand years or longer. This paper proposes a concept of enhanced mineral trapping system of CO2 geological storage by means of microbially mediated processes and describes some results of related preliminary microbial experiments. Environmental microorganisms have influences on groundwater chemistry and mineral precipitation and dissolution, and even accelerate mineral precipitation processes. The research objective is to accelerate mineral trapping by microbial activities. Especially, biomineralization of carbonate minerals acts an important role for the enhanced mineral trapping system. It is expected to reduce the time scale of mineral trapping from several thousand years to several decades (human life time). It is also expected to play a role for sealing capability. The goal of the research project is to extract optimum bacteria to form carbonate-forming habitats and to evaluate the possibility of bacteria-enhanced CO2 geological storage using numerical model. To develop the system, we plan to carry out the following four procedures; (1) looking for various kinds of carbonate-forming bacteria from natural samples, (2) extraction of bacteria for the condition of the system and further extraction of the bacteria with optimum performance of carbonate precipitation by laboratory experiments, (3) measurement the microbial kinetic parameters, such as specific growth rate of the bacteria by some laboratory experiments (4) performance assessment by hydro-bio-geochemical modeling using experimental data including microbial kinetic parameters. According to the research plan, we carried out literature investigation to make an inventory and preliminary laboratory experiments as the first step of looking for the optimum bacteria. Our target is biomineralization by moderately halophilic carbonate-forming bacteria, which few researchers have studied yet. Screenings of bacteria consists mainly of three steps as follows: 1) purchase of moderately halophilic bacteria, some of which are known carbonate-forming species, 2) selection of carbonate-formers from the isolated halophiles, and 3) selection of practically applicable carbonate-formers with higher performances. Preliminary batch culture experiments were performed with purchased different 6 species of moderately halophilic bacteria; Chromohalobacter marismortui, Halobacillus trueperi, Halomonas halophila, Marinobacter hydrocarbonoclasticus, Marinococcus halophilus, and Virgibacillus salexigens. Initial concentration of Ca2+ was set between 2.60 g/l and 2.75 g/l in the liquid cultures. Gradual decrease in Ca2+ concentration was observed for all microbial samples. After 98 days, Ca2+ concentration in the liquid culture of Mb. hydrocarbonoclasticus was 0.440 g/l. Ca2+ concentration of C. marismortui was 0.448 g/l after 189 days. Decrease in Ca2+ concentration was also observed for other 4 microbial species, although its degree and decreasing rate varied among species. Meanwhile, decrease in Ca2+ concentration was not observed in abiotic liquid culture. Chemical analysis by EPMA was also carried out for some microbes after the incubation, and higher peak of calcium, oxygen, carbon and minor magnesium were detected. These results indicate that the decrease in Ca2+ concentration was caused by microbial carbonate precipitation. [Copyright &y& Elsevier]

Abstract: Geologic sequestration of CO2 involves injection into underground formations including oil beds, deep un-minable coal seams, and deep saline aquifers with temperature and pressure conditions such that CO2 will likely be in the supercritical state. It is important that the receiving aquifer have sufficient porosity and permeability and be overlain by a suitable low-permeability cap rock formation. Supercritical CO2 injected into the receiving formation is only slightly soluble in water (approximately 4%) and therefore two fluid phases develop. Also, supercritical CO2 is less dense and much less viscous than the initially resident brine resulting in the potential for upward leakage of CO2 through fractures, disturbed rock, or cement lining near injection wells. This paper summarizes recent research on microbially-based strategies for controlling leakage of CO2 during geologic sequestration. We examine the concept of using engineered microbial biofilms which are capable of precipitating crystalline calcium carbonate using the process of ureolysis. The resulting combination of biofilm plus mineral deposits, if targeted near points of CO2 injection, may result in the long-term sealing of preferential leakage pathways. Successful development of these biologically-based concepts could result in a CO2 leakage mitigation technology which can be applied either before CO2 injection or as a remedial measure. [Copyright &y& Elsevier]

Examines the microbiological and chemical characteristics of the production fluids of the high-temperature Liaohe oil field in China to investigate the potential for microbially enhanced oil recovery. Characterization of the sampling area; Enumeration of bacteria; Chemical and microbiological characteristics of the formation waters; Rates of microbiological processes in formation waters.

Abstract Microbial enhanced oil recovery (MEOR) process utilizes reservoir microorganisms (in situ) or specially selected bacteria to use their metabolic products (ex-situ) for extra oil recovery from depleted oil reservoirs. Biodegradation of crude oil and simultaneous production of bioemulsifiers by a mixed culture consisting of Ochrobactrum pseudintermedium C1 and Bacillus cereus K1 have been investigated in this study along with the potential ex-situ application of bioemulsifier in MEOR process. The culture parameters namely pH, temperature, aeration rate and agitation rate have been optimized in a lab scale bioreactor using Taguchi's L9 orthogonal array approach to increase the rate of biodegradation of crude oil. At optimized culture condition (pH 8.0, temperature 35 °C, aeration rate 1.5Nl/min and agitation rate 150 rpm), the bacterial consortium degrade up to 70.54% of total petroleum hydrocarbons (TPH) after 72 h incubation using crude oil (4% v/v) as the sole source of carbon and produced two different exopolysaccharides (EPS), which showed very good emulsification activity (EI) towards crude oil up to 80.5% and also reduced the interfacial tension of crude-oil water system from 46 mN/m to 14.5 mN/m. FT-IR, NMR and chemical analyses revealed that EPS formed by C1 contained 61.5% (w/w) carbohydrates, 29.2% protein and 9.3% lipid whereas, the EPS formed by K1 comprises of 43.6% (w/w) carbohydrates, 51.7% lipids and 6.3% protein. The crude bioemulsifier mixture was found to be pseudoplastic, Non-Newtonian in nature and was stable at a wide range of pH (2−10), temperature (40–121 °C) and salinity (0–15% w/v), hence signifies its applicability in MEOR process. The results of the sand pack column flooding tests at simulated reservoir conditions demonstrated that the additional oil recovery efficiency due to the ex-situ injection of the cell-free bioemulsifier solution was 40.93% and 46.85% at 40 °C and 70 °C temperatures respectively. The mixed culture presented a great potential application in bioremediation of oil polluted sites owing to its degradation ability to crude oil and also in enhanced oil recovery process using the crude bioemulsifier having combined surface and emulsification activity. Graphical abstract Image 1 Highlights • Dual role of a microbial consortium for crude oil spill bioremediation and microbial enhanced oil recovery. • Biodegradation of crude oil with simultaneous production of bioemulsifier. • Bioemulsifier possesses both emulsification and surface activity. • Suitability of the bioemulsifier as an MEOR agent under extreme environmental conditions. • Ex-situ application of the bioemulsifier enhanced oil recovery significantly after primary water flooding. [ABSTRACT FROM AUTHOR]