Volume 48, Issue No 2

Surfactin – A Review on Biosynthesis, Fermentation, Purification and Applications

Nikhil S. Shaligram and Rekha S. Singhal*

Food Engineering and Technology Department, Institute of Chemical Technology, Matunga, Mumbai, IN-400 019 India

Article history:
Received January 28, 2009
Accepted January 11, 2010

Key words:
biosurfactant, surfactin, Bacillus subtilis, biosynthesis, fermentation, purification

Summary:
Surfactin, a bacterial cyclic lipopeptide, is produced by various strains of Bacillus subtilis and is primarily recognized as one of the most effective biosurfactants. It has the ability to reduce surface tension of water from 72 to 27 mN/m at a concentration as low as 0.005 %. The structure of surfactin consists of seven amino acids bonded to the carboxyl and hydroxyl groups of a 14-carbon fatty acid. Surfactin possesses a number of biological activities such as the ability to lyse erythrocytes, inhibit clot formation, lyse bacterial spheroplasts and protoplasts, and inhibit cyclic 3',5-monophosphate diesterase. The high cost of production and low yields have limited its use in various commercial applications. Both submerged and solid-state fermentation have been investigated with the mutational approach to improve the productivity. In this review, current state of knowledge on biosynthesis of surfactin, its fermentative production, purification, analytical methods and biomedical applications is presented.

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From DNA Sequences to Chemical Structures – Methods for Mining Microbial Genomic and Metagenomic Data Sets for New Natural Products 

Jurica Zucko^1,3, Antonio Starcevic^1,3, Janko Diminic¹, Mouhsine Elbekali³, Mohamed Lisfi³, Paul F. Long², John Cullum³ and Daslav Hranueli¹*

¹Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10000 Zagreb, Croatia
²School of Pharmacy, University of London, 29/39 Brunswick Square, London WC1N 1AX, United Kingdom
³Department of Genetics, University of Kaiserslautern, Postfach 3049, DE-67653 Kaiserslautern, Germany

Article history:
Received March 19, 2009
Accepted January 26, 2010

Key words:
polyketides, non-ribosomal peptides, Actinobacteria, homologous recombination

Summary:
Rapid mining of large genomic and metagenomic data sets for modular polyketide synthases, non-ribosomal peptide synthetases and hybrid polyketide synthase/non-ribosomal peptide synthetase biosynthetic gene clusters has been achieved using the generic computer program packages ClustScan and CompGen. These program packages perform the annotation with the hierarchical structuring into polypeptides, modules and domains, as well as storage and graphical presentations of the data. This aims to achieve the most accurate predictions of the activities and specificities of catalytically active domains that can be made with present knowledge, leading to a prediction of the most likely chemical structures produced by these enzymes. The program packages also allow generation of novel clusters by homologous recombination of the annotated genes in silico. ClustScan and CompGen were used to construct a custom database of known compounds (CSDB) and of predicted entirely novel recombinant products (r-CSDB) that can be used for in silico screening with computer aided drug design technology. The use of these programs has been exemplified by analysing genomic sequences from terrestrial prokaryotes and eukaryotic microorganisms, a marine metagenomic data set and a newly discovered example of a 'shared metabolic pathway' in marine-microbial endosymbiosis.

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Trans Fatty Acids in Food and Their Influence on Human Health

Sebastjan Filip¹, Rok Fink², Janez Hribar¹ and Rajko Vidrih¹*

¹Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia
²Department of Sanitary Engineering, Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, SI-1000 Ljubljana, Slovenia

Article history:
Received February 25, 2009
Accepted December 10, 2009

Key words:
trans fatty acids, human nutrition, human health, hydrogenated fats

Summary:
Hydrogenated oils tend to have a higher trans fatty acid (TFA) content than oils that do not contain hydrogenated fats. Prospective epidemiological and case-control studies support a major role of TFAs in the risk of cardiovascular disease. In the partially hydrogenated soybean oil, which is the major source of TFAs worldwide, the main isomer is trans-10 C18:1. In the European countries with the highest TFA intake (the Netherlands and Norway), consumption of partially hydrogenated fish oils was common until the mid-1990s, after which they were omitted from the dietary fat intake. These partially hydrogenated fish oils included a variety of very long-chain TFAs. Recent findings from Asian countries (India and Iran) have indicated a very high intake of TFAs from partially hydrogenated soybean oil (4 % of energy). Thus TFAs appear to be a particular problem in developing countries, where soybean oil is used. In 2003, the United States Food and Drug Administration issued a final ruling that required food manufacturers to list the TFAs in their foods on the nutritional facts label. One way to produce 'zero' levels of TFAs is the trans-esterification reaction between vegetable oils and solid fatty acids, like C8:0, C12:0, C14:0 and C16:0.

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