Escherichia coli remains the best established production organisms in industrial biotechnology. However, during aerobic fermentation runs at high growth rates, considerable amounts of acetate are accumulated as by-product. This by-product has negative effects on growth and protein production. Over the last 20 years, substantial research efforts have been spent to reduce acetate accumulation during aerobic growth of E. coli on glucose. From the onset it was clear that this quest should not be a simple nor uncomplicated one. Simple deletion of the acetate pathway, reduced the acetate accumulation, but instead other by-products were formed. This minireview gives a clear outline of these research efforts and the outcome of them, including bioprocess level approaches and genetic approaches. Recently, the latter seems to have some promising results

The aim of this study was to assess the potential of lactic acid bacteria to inhibit the outgrowth of some common food-spoiling fungi. Culture supernatants of 17 Lactic acid bacterial strains as well as of three commercial probiotic cultures were evaluated for antifungal activity using an agar-diffusion method. The method parameters were chosen in order to reveal compounds for potential use in food (bio)preservation. Thirteen strains showed antifungal activity of which five strains were very promising: Lactobacillus acidophilus LMG 9433, L. amylovorus DSM 20532, L. brevis LMG 6906, L. coryniformis subsp. coryniformis LMG 9196 and L. plantarum LMG 6907. Four of these five strains were further examined; it was found that the produced antifungal metabolites were pH-dependent. The exact chemical nature of these substances has not been revealed yet.

1,3-Propanediol (PDO) is the starting point of a new-generation polymer with superior properties which is used in the textile and carpet industry. This product is mainly produced chemically, but high pressure, high temperature and expensive catalysts are required and toxic intermediates are released. Therefore, the biological production route has been studied intensively. DuPont and Genencor International, Inc. have modified Escherichia coli genetically so that this organism could produce PDO from glucose. However, due to the tremendous growth of the biofuel industry, a glycerol surplus has been created, so more and more researchers started to investigate the natural producing strains for the production of PDO from glycerol. Several metabolic engineering techniques have been used to enhance the production of PDO. This contribution gives an overview of the different strategies to increase the final titer, yield, and productivity of 1,3-propanediol in non-natural and natural producing strains.

Recent developments in cellular and molecular biology require the accurate quantification of DNA and RNA in large numbers of samples at a sensitivity that enables determination on small quantities. Five current methods for nucleic acid quantification have been compared: 1) UV absorbance spectroscopy at 260nm, 2) Colorimetric reaction with the orcinol reagent, 3)Colorimetric reaction based on diphenylamine, 4) Fluorescence detection with reagent Hoechst 33258 and 5) Fluorescence detection with thiazole orange reagent. Genomic DNA of three different microbial species (with widely different G+C content) was used as well as two different types of yeast RNA and a mixture of equal quantities of DNA and RNA.We can conclude that for nucleic acid quantification a standard curve with DNA of the microbial strain under study is the best reference. Fluorescence detection with reagent Hoechst 33258 ® is a sensitive and precise method for DNA quantification if the G+C content is lower than 50%. In addition this method allows quantification of very low levels of DNA (ng-scale). Moreover, the samples can be crude cell extracts. Also UV absorbance at 260nm and fluorescence detection with thiazole orange reagent are sensitive methods for nucleic acid detection, but only if purified nucleic acids have to be measured.

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