Production of red yeast rice rich in monacolin K by variable temperature solid fermentation of Monascus purpureus.

Hypercholesterolemia represents a serious public health problem as it significantly increases the risk of developing cardiovascular diseases. Monacolin K (MK) in red yeast rice is an active compound that can effectively lower plasma cholesterol. To enhance the yield of MK in solid state fermentation of Monascus purpureus HNU01, the effects of different variables were systematically examined in single-factor experiments. The optimal conditions for the production of red yeast rice rich in MK were as follows: initial pH value 5.5, initial moisture content 40% w/w, glucose 50 g L-1, peptone 20 g L-1, MgSO4 0.5 g L-1, KH2PO4 1 g L-1, variable temperature fermentation (30 °C for the first 3 days and then 24 °C for 15 days), total fermentation time of 18 days, and additional water added at day 4 at 10% w/w. Under the above optimized conditions, the MK content of red yeast rice produced by fermentation was 9.5 mg g-1. No citrinin was detected in any of the batches of fermentation products. The results will be useful for the large-scale production of high-quality red yeast rice with health benefits for consumers.

Genetically Engineering Escherichia coli to Produce Xylitol from Corncob Hydrolysate without Lime Detoxification.

Before fermentation with hemicellulosic hydrolysate as a substrate, it is generally necessary to detoxify the toxic substances that are harmful to microorganism growth. Cyclic AMP receptor protein (CRP) is a global regulator, and mutation of its key sites may have an important impact on E. coli virulence tolerance. Using corncob hydrolysate without ion-exchange or lime detoxification as the substrate, shake flask fermentation experiments showed that CRP mutant IS5-dG (I112L, T127G, A144T) produced 18.4 g/L of xylitol within 34 h, and the OD600 was 9.7 at 24 h; these values were 41.5% and 21.3% higher than those of the starting strain, IS5-d, respectively. This mutant produced 82 g/L of xylitol from corncob hydrolysate without ion-exchange or lime detoxification during fed-batch fermentation in a 15-L bioreactor, with a productivity of 1.04 g/L/h; these values were 173% and 174% higher than the starting strain, respectively. To our knowledge, this is the highest xylitol concentration and productivity produced by microbial fermentation using completely non-detoxified hemicellulosic hydrolysate as the substrate to date. This study also showed that alkali neutralization, high temperature sterilization, and fermentation of the hydrolysate had important effects on the xylose loss rate and xylitol production.

[Decolorization conditions for reactive brilliant blue KN-R by three fungi].

Seventeen strains with wideranging decolorization ability were screened from contaminated soil and were applied on the decoloring of dye wastewater. Three strains were selected due to their high decolorization capacity on azo dyes, anthraquinone dyes and triphenylmethane dyes. The three strains were named as Strain I, Strain II, Strain III. This three superior strains were identified as penicillium link (Strain I & strain II) and Cephalosporium corda (strain III). Using aqueous samples, the influences of several factors on decolorization were reported, such as pH, carbon source, temperature and so on. And then applying of these strains for treatment of actual wastewater have also been done. The results showed that the optimal pH, temperature and carbon source were 5-9, 18-37 degrees C and 0.5% respectively, under those conditions the decolorization removal rate was 70%. And these fungi have a good prospect for the treatment of dye wastewater.