Biosurfactants are surface-active compounds synthesized by microbes. They have the ability to reduce the surface tension of a liquid and interfacial tension (IFT) between two different phases. Thus, they can be applied in water-oil emulsification. The development of enhanced oil recovery (EOR) technology has led to increased interest in biosurfactants. The purpose of this review was to compile information on important components of biosurfactant production. Understanding the characteristics of biosurfactants, especially IFT derivation and effects of alterations in the wettability of reservoir rocks can aid the applications in EOR. Both the microbe type and growth substrate influence the yield and type of biosurfactant produced. The type of fermenter also affects the efficiency of surfactant production. The use of batch type fermentors and the use of Pseudomonas and Bacillus bacteria in the previous research was superior whereas the sugar group and plant base oil as substrates. The measurement methods of biosurfactants in microbial culture are of considerable importance to be done prior to characterization of biosurfactant products. Furthermore, some reservoir components discussed in this review are the keys to the success of biosurfactant flooding in the field.

Biosurfactants are one of the microbial bioproducts that are in most demand from microbial-enhanced oil recovery (MEOR). The production of biosurfactant is still a relatively high cost. Therefore, this study aims to reduce production costs by utilizing palm oil mill effluent (POME) as the main carbon source. This work examines the optimal conditions of biosurfactant production by Halomonas meridiana BK-AB4 isolated from the Bledug Kuwu mud volcano in Central Java Indonesia and studies it for EOR applications. The biosurfactant production stage was optimized by varying POME concentration, incubation time, NaCl concentration, and pH to obtain the maximum oil displacement area (ODA) values. A response surface methodology (RSM) and a central composite design (CCD) were used to identify the influence of each variable and to trace the relationship between variables. Optimum biosurfactant production was found at a POME concentration (v/v) of 16%, incubation (h) of 112, NaCl concentration (w/v) of 4.7%, pH of 6.5, with an oil displacement area of 3.642 cm. The LC-MS and FTIR analysis revealed the functional groups of carboxylic acid or esters, which indicated that the biosurfactant produced belonged to the fatty acid class. The lowest IFT value was obtained at the second and seventh-day observations at a concentration of 500 mg/L, i.e., 0.03 mN/m and 0.06 mN/m. The critical micelle concentration (CMC) of biosurfactant was about 350 mg/L with a surface tension value of about 54.16 mN/m. The highest emulsification activity (E24 = 76%) in light crude oil (naphthenic–naphthenic) and could reduce the interfacial tension between oil and water up to 0.18 mN/m. The imbibition experiment with biosurfactant results in 23.89% additional oil recovery for 60 h of observation, with the highest increase in oil recovery occurring at the 18th hour, which is 2.72%. Therefore, this bacterium and its biosurfactant show potential, and the bacterium are suitable for use in MEOR applications.

This study aims to find growth medium commercial yeast (S.cerevisiae) and determine the optimum composition of bioethanol fermentation. This research was conducted at the Laboratory of Bioprocess PPPTMGB "LEMIGAS" along May to September 2015. The method used is experiment using a completely randomized design consisting of two treatment. The first treatment is an alternative growth media utilization, namely, tofu liquid waste, coconut water and a mixture of both. The second treatment is the composition of the fermentation with sugar content of 100 ml, 150 ml and 200 ml with the addition of 10 ml starter in each experiment. Data of commercial yeast cell growth (S.cerevisiae) on alternative growth media were analyzed by Anova one way. The results showed that there was an interaction of commercial yeast cell growth (S.cerevisiae) on alternative growth media. Post-hoc test showed the alternative media that consists of a mixture of tofu liquid waste and coconut water produce the highest commercial yeast cell growth at 25,8 x107 with a 7.62 log value (cells/ml). The most optimum of bioethanol produced in the fermentation process is on sugar 100 ml by the addition of 10 ml starter acquire as much as 45 ml of ethanol content.

Biosurfactant is produced by a certain microorganism to reduce surface tension. Microbial enhanced oil recovery (MEOR) is one of the many applications of biosurfactant. However, the biosurfactant for MEOR needs to be able to withstand the extreme environment of oil reservoirs with high temperature and high salinity. Halomonas meridiana BK-AB4 is a halophilic bacterium obtained from the Bledug Kuwu crater in Central Java, Indonesia. The similarity of both environment condition indicates the potential to produce suitable biosurfactant. This study evaluates the potential of Halomonas meridiana BK-AB4 in producing biosurfactant compared to several bacteria isolated from the crater. The blood agar test of Halomonas meridiana BK-AB4 exhibited greenish discoloration around the colony, indicating the ability of type α-hemolysis. The interfacial tension was measured using the Du Nouy ring method to represent the biosurfactant activity, with the results of 0.014 dyne/cm. These results showed that Halomonas meridiana BK-AB4 has a very good potential for producing biosurfactant for MEOR. The optimum time of the culture starter for production is 6 hours, as determined from the bacterial growth curve.

Biobutanol is one of the promising biofuel for substituting gasoline. Biobutanol produced from biomass fermentation using solventogenic clostridia which are able to convert a wide range of carbon sources to fuels such as butanol. Therefore, lignocellosic biomass has great potential as fermentation substrate for biobutanol production. Lignocellosic biomass should be hydrolized before fermentation by a pretreatment process and enzymatic hydrolysis. The various lignocellulosic biomass pretreatment will infl uence in butanol production depending on fermentable sugars content. The objective of this research is to get potential lignocellulosic biomass using dilute acid pretreatment and enzymatic hydrolysis process for biobutanol production. Eight types of biomass from sugarcane bagasse, rice straw, rice husk, empty fruit bunch (EFB) of palm oil, corn cob, pulp waste, traditional market organic waste, and microalgae were used in this experiment. After hydrolysis, the high result of total fermentable sugars in corn cobs, bagasse, rice straw, and rice husk, shows good opportunity of these biomass to be used as fermentation feedstocks for biobutanol production. In addition, pulp waste, organic waste, and microalgae are prospective as raw material but require more appropriate treatment either for to break down the cellulose/hemicellulose or to enhance reducing sugar content. Fine milling and delignifi cation have no signifi cant effect on cellulosic biomass conversion into fermentable sugars. Therefore, the production cost can be reduced. In order to enhance the sugar content and reduce the formation of inhibitor product, it is necessary to examine dilute acid pretreatment variations and appropriate operating conditions of enzymatic hydrolysis process