Surfactants microbial

The B. licheniformis JF-2 strain produces a very effective surfactant under conditions typical of oil reservoirs. The partially purified biosurfactant from JF-2 was shown to be the most active microbial surfactant found, and it gave an interfacial tension against decane of 0.016 mN/m. An optimal production of the surfactant was obtained in cultures grown in the presence of 5% NaCl at a temperature of 45° C and pH of 7. TTie major endproducts of fermentation were lactic acid and acetic acid, with smaller amounts of formic acid and acetoin. The growth and biosurfactant formation were also observed in anaerobic cultures supplemented with a suitable electron acceptor, such as NaNO3[1106]. 

Rosenberg, E. and Ron, E. Z. (1999). High- and low-molecular-mass microbial surfactants, Appl. Microbiol. Biotechnol., 52, 154-162. 

Surfactants are used widely in industry, agriculture and medicine. The materials currently in use are produced primarily by chemical synthesis, or as by-products of industrial processes. For a microbial surfactant to penetrate the market, it must provide a clear advantage over the existing competing materials. The major considerations are (1) safety, i.e., low toxicity and biodegradability (2) cost (3) selectivity and (4) specific surface modifications. Biosurfactants exhibit low toxicity and good biodegradability, properties that are essential if the surfactant is to be released into the environment. 

Rosenberg, E. (1986). Microbial surfactants. CRC Critical Reviews in Biotechnology, 3,109-32. 

Oberbremer, A., Muller-Hurtig, R. Wagner, F. (1990). Effect of the addi tion of microbial surfactants on hydrocarbon degradation in a soil population in a stirred reactor. Applied Microbiology and Biotechnology, 32, 485-9-... 

Among the microbial surfactant producers, Bacillus subtilis strains generate a lipopeptide called surfactin, one of the most effective biosurfactants known. This biomolecule is usually a cyclic compound consisting of seven amino acids bonded to a lipid moiety. Surfactin is effective in lowering the surface tension of water to <30 dyn/cm (17), which is comparable with the values obtained by conventional synthetic surfactants. Additionally, surfactin preparations have other interesting characteristics, including antibiotic and antiviral properties (18). In fact, surfactin is one of the few biosurfactants that has found commercial use (19). 

The question what is the natural role of microbial surfactants would appear to be of fundamental significance in microbial physiology and of practical value in designing selection methods for improved molecules. However, the question has a basic flaw. There is no reason to suspect that surfactants have one natural role. As described in this chapter, microbial surfactants have very different structures, are produced by a wide variety of microorganisms, and have very different surface properties. Thus, it will be necessary to analyze each surfactant, or group of surfactants, separately. Only then may it be possible to draw any generalizations. 

Inoue S, Itoh S (1982) Sophorolipids from Torulopsis bombicola as microbial surfactants in alkane fermentation. Biotechnol Lett 4 308-312 Isoda H, Shinmoto H, Kitamoto D, Matsumura M, Nakahara T (1997) Differentiation of human promyelocytic leukemia cell line HL60 by microbial extracellular glycolipids. Lipids 32 263-271... 

Itoh S, Inoue S (1982) Sophorolipids from Torulopsis bombicola as microbial surfactants in alkane fermentations. Appl Environ Microbiol... 

Banat, I. M., Makkar, R., Cameo tra, S. Potential commercial applications of microbial surfactants. 4/7p/M crof)ro/Biofec/rwoZ. 2000, 53,495-508. 

Bordoloi, N. K., Konwar, B. K. Microbial surfactant-enhanced mineral oil recovery imder laboratory conditions. Colloids SurfB Biointeifaces 2008,63,73-82. 

Pomsunthomtawee, O., Arttaweepom, N., Paisanjit, S., Somboonthanate, P, Abe, M., Rujira-vanit, R., Chavadej, S. Isolation and comparison of biosuifactants produced by Bacillus subtilis PT2 and Pseudomonas aeruginosa SP4 for microbial surfactant enhanced oil recovery. Biochem EngJ. 2008,42,172-179. 

Singh, P, Cameotra, S. Potential applications of microbial surfactants in biomedical sciences. Trends Biotechnol. 2004,22,142-146. 

Table 11 Important Microbial Surfactants and Their Main Products... 

The enzymatic synthesis of surfactants, on the other hand, is in essence a chemical reaction in which an enzyme (in a form isolated from its source or even as whole cells) replaces a conventional chemical catalyst. In contrast to the microbial surfactants mentioned above, the surfactants obtained by the use of single enzymes are simpler in structure but can be designed to have the desired physicochemical features. The scope of this chapter is limited to production of surfactants using enzymes and will not include microbial surfactants. 

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