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Summary: Bioactive peptides generated from food proteins have gained much interest as functional foods. Recently, the application of lactic acid fermentation has developed rapidly thanks to the discovery of probiotic functions in lactic acid bacteria (LAB). Aside from converting a fermentable carbohydrate into lactic acid, many strains of LAB were found to possess proteolytic activity, which is essential for many fermentation processes. The protease enzymes produced from the proteolytic fermentation breakdown proteins in food and generate a variety of high‐value products which are discussed in this review. These substances give rise to the production of functional food that exerts diverse health benefits including antioxidant, antihypertension, antihyperglycaemic, antiinflammation, antimicrobial, and anticancer effects. The effects of proteolytic fermentation on the physicochemical and functional properties, biological activities, and sensory attributes of foods are elaborated in this review article. The application of proteolytic fermentation in various food industries, mainly the dairy industry, meat industry, bakery industry, and brewing industry, improved the technological, nutritional, biological, and sensory characteristics, as well as increased the shelf life of food. Ultimately, this review summarises in‐depth knowledge of proteolytic fermentation by LAB and generates additional interest in the development of novel proteolytically fermented products. [ABSTRACT FROM AUTHOR]

Zearalenone, a secondary metabolite produced by several plant-pathogenic fungi of the genus fusarium, has high estrogenic activity in vertebrates. A Saccharomyces cerevisiae bioassay strain was developed that was used to identify plant genes encoding UDP-glucosyltransferases that can convert zearalenone into zearalenone-4-O-glucoside (Zon-4-O-Glc).

Research has been conducted on Trametes pubescens laccase isoenzyme LAP2. The purification and characterization of this laccase by the fungus T. pubescens has been carried out under the copper growth conditions and its regulation has been investigated and described.

A reporter system based on the Aspergillus niger glucose oxidase was used to examine the regulation of expression of two major chitinase genes from the mycoparasitic biocontrol fungus Trichoderma atroviride. These are ech42, which encodes the CHIT42 endochitinase, and nag1, which encodes the CHIT73 N-acetyl-beta-D-glucosaminidase. Results demonstrate the difference in the mechanism of regulation of nag1 and ech42 expression. While nag1 is induced by low-molecular-weight chitooligosaccharides and its own catabolic products, ech42 seems not to be directly triggered by purified chitin or chitooligosaccharides, but by carbon starvation and some stress conditions.

Addition of different enzymes to fungitoxic compounds, including gliotoxin, flusilazole, miconazole, captan and benomyl, enhances antifungal action on Botrytis cinerea. The Trichoderma harzianum strain P1 endochitinase fungicides. Hydrolytic enzymes may be used to synergistically increase antifungal capability of fungitoxic compounds.

Abstract Background Two sets of overlapping genes, lacLMReu and lacLMAci, encoding heterodimeric β-galactosidases from Lactobacillus reuteri and Lactobacillus acidophilus, respectively, have previously been cloned and expressed using the pSIP vector system and Lactobacillus plantarum WCSF1 as host. Despite the high similarity between these lacLM genes and the use of identical cloning and expression strategies, strains harboring lacLMReu produced about twenty-fold more β-galactosidase than strains containing lacLMAci. Results In this study, the plasmid copy numbers (PCN) of expression vectors pEH9R (lacLMReu) and pEH9A (lacLMAci) as well as the transcription levels of both lacLM genes were compared using quantitative PCR methods. Analyses of parallel fermentations of L. plantarum harboring either pEH9R or pEH9A showed that the expression plasmids were present in similar copy numbers. However, transcript levels of lacLM from L. reuteri (pEH9R) were up to 18 times higher than those of lacLM from L. acidophilus (pEH9A). As a control, it was shown that the expression levels of regulatory genes involved in pheromone-induced promoter activation were similar in both strains. Conclusion The use of identical expression strategies for highly similar genes led to very different mRNA levels. The data indicate that this difference is primarily caused by translational effects that are likely to affect both mRNA synthesis rates and mRNA stability. These translational effects thus seem to be a dominant determinant for the success of gene expression efforts in lactobacilli.

Abstract Background The flavin-dependent enzyme pyranose 2-oxidase (P2Ox) has gained increased attention during the last years because of a number of attractive applications for this enzyme. P2Ox is a unique biocatalyst with high potential for biotransformations of carbohydrates and in synthetic carbohydrate chemistry. Recently, it was shown that P2Ox is useful as bioelement in biofuel cells, replacing glucose oxidase (GOx), which traditionally is used in these applications. P2Ox offers several advantages over GOx for this application, e.g., its much broader substrate specificity. Because of this renewed interest in P2Ox, knowledge on novel pyranose oxidases isolated from organisms other than white-rot fungi, which represent the traditional source of this enzyme, is of importance, as these novel enzymes might differ in their biochemical and physical properties. Results We isolated and over-expressed the p2ox gene encoding P2Ox from the ectomycorrhizal fungus Lyophyllum shimeji. The p2ox cDNA was inserted into the bacterial expression vector pET21a(+) and successfully expressed in E. coli Rosetta 2. We obtained active, flavinylated recombinant P2Ox in yields of approximately 130 mg per L of medium. The enzyme was purified by a two-step procedure based on anion exchange chromatography and preparative native PAGE, yielding an apparently homogenous enzyme preparation with a specific activity of 1.92 U/mg (using glucose and air oxygen as the substrates). Recombinant P2Ox from L. shimeji was characterized in some detail with respect to its physical and catalytic properties, and compared to the well-characterised enzymes from Phanerochaete chrysosporium and Trametes multicolor. Conclusion L. shimeji P2Ox shows properties that are comparable to those of P2Ox from white-rot fungal origin, and is in general characterised by lower Km and kcat values both for electron donor (sugar) as well as electron acceptor (ferrocenium ion, 1,4-benzoquinone, 2,6-dichloroindophenol). While L. shimeji P2Ox is the least thermostable of these three enzymes (melting temperature Tm of 54.9°C; half-life time of activity τ1/2 of 0.12 at 50°C and pH 6.5), P. chrysosporium P2Ox showed remarkable thermostability with Tm of 75.4°C and τ1/2 of 96 h under identical conditions.

Abstract The heterologous production of the industrially relevant fungal enzyme pyranose 2-oxidase in the prokaryotic host E. coli was investigated using 3 different expression systems, i.e. the well-studied T7 RNA polymerase based pET21d+, the L-arabinose inducible pBAD and the pCOLD system. Preliminary experiments were done in shaking flasks at 25°C and optimized induction conditions to compare the productivity levels of the different expression systems. The pET21d+ and the pCOLD system gave 29 U/L·h and 14 U/L·h of active pyranose 2-oxidase, respectively, whereas the pBAD system only produced 6 U/L·h. Process conditions for batch fermentations were optimized for the pET21d+ and the pCOLD systems in order to reduce the formation of inactive inclusion bodies. The highest productivity rate with the pET21d+ expression system in batch fermentations was determined at 25°C with 32 U/L·h. The pCOLD system showed the highest productivity rate (19 U/L·h) at 25°C and induction from the start of the cultivation. Using the pCOLD system in a fed batch fermentation at 25°C with a specific growth rate of μ = 0.15 h-1resulted in the highest productivity rate of active pyranose oxidase with 206 U/L·h.