Biochemical tests as an aid to the identification of Monascus species

Ensiled Mixed Vegetables Enriched Carbohydrate Metabolism in Heterofermentative Lactic Acid Bacteria

This study evaluated the fermentation quality, nutritive profile, in vitro fermentation, and microbial communities colonising sorghum ensiled with an unsalable vegetable mixture (chopped beans, carrot, and onion (1:1:1) ) including: (1)−100% sorghum; (2)−80% sorghum + 20% vegetable mix or (3)−60% sorghum + 40% vegetable mix, on a dry matter (DM) basis, with or without a probiotic inoculant. Samples were obtained across 0, 1, 3, 5,7, and 101 days ensiling and after 14 d aerobic exposure. The V4 region of the 16S rRNA gene and the ITS1 region were sequenced to profile bacterial, archaeal, and fungal communities. Compared to the 0% DM, ethanol increased (p < 0.01) from 8.42 to 20.4 ± 1.32 mM with 40% DM vegetable mix inclusion, while lactate decreased from 5.93 to 2.24 ± 0.26 mM. Linear discriminant analysis revealed that relative abundances of 12 bacterial taxa were influenced by silage treatments (log LDA score ≥ 4.02; p ≤ 0.03), while predicted functional pathways of alternative carbohydrate metabolism (hexitol, sulfoquinovose and glycerol degradation; N-acetyl glucosamine biosynthesis; log LDA score ≥ 2.04; p ≤ 0.02) were similarly enriched. This study indicated that carbohydrate metabolism by heterofermentative lactic acid bacteria can increase the feed value of sorghum when ensiled with an unsalable vegetable mixture at 40%DM, without requiring a high quantity of lactate.

Agro-industrial residues for the production of red biopigment by Monascus ruber: rice flour and sugarcane molasses

Three culture media were studied for red pigment production by Monascus ruber in submerged cultivation: rice flour (20 g L^-1), sugarcane molasses (30 g L^-1), and, finally, molasses + rice flour (10 g L^-1+10 g L^-1); all culture media were added of 5 g L^-1 glycine as nitrogen source. Rice flour showed pigment production of 7.05 UA_510nm and molasses 5.08 UA_510nm, and the mixture of rice flour and molasses showed the best result of 16.38 UA_510nm. Molasses culture presented good results for cell biomass production of 11.09 g L^-1. With these results, it was observed that one substrate presented good pigment production (rice flour) and another attained better results for cell biomass growth (molasses), and a third medium containing 10 g L^-1 of rice flour + 10 g L^-1 of molasses was formulated. The results for this mixture showed satisfactory results, with global pigment productivity of 0.097 UA_510nm h^-1 and maximum productivity rate of 0.17 UA_510nm h^-1. The high production and productivity obtained for the mixture of rice flour and molasses indicated that the production of red pigment by submerged fermentation, using the mixture of these low-cost culture media, may be promising in terms of commercial production.

Monascus secondary metabolites: production and biological activity

The genus Monascus, comprising nine species, can reproduce either vegetatively with filaments and conidia or sexually by the formation of ascospores. The most well-known species of genus Monascus, namely, M. purpureus, M. ruber and M. pilosus, are often used for rice fermentation to produce red yeast rice, a special product used either for food coloring or as a food supplement with positive effects on human health. The colored appearance (red, orange or yellow) of Monascus-fermented substrates is produced by a mixture of oligoketide pigments that are synthesized by a combination of polyketide and fatty acid synthases. The major pigments consist of pairs of yellow (ankaflavin and monascin), orange (rubropunctatin and monascorubrin) and red (rubropunctamine and monascorubramine) compounds; however, more than 20 other colored products have recently been isolated from fermented rice or culture media. In addition to pigments, a group of monacolin substances and the mycotoxin citrinin can be produced by Monascus. Various non-specific biological activities (antimicrobial, antitumor, immunomodulative and others) of these pigmented compounds are, at least partly, ascribed to their reaction with amino group-containing compounds, i.e. amino acids, proteins or nucleic acids. Monacolins, in the form of β-hydroxy acids, inhibit hydroxymethylglutaryl-coenzyme A reductase, a key enzyme in cholesterol biosynthesis in animals and humans.

Based on biochemical and physiological behavior, where is Aspergillus egyptiacus better placed?

Physiological and biochemical properties were tested in 45 isolates of Aspergillus egyptiacus (16 isolates), Emericella nidulans (16) and Aspergillus versicolor (13). The three fungal species exhibited common and similar features. The big similarity between A. egyptiacus and E. nidulans was greater than between A. egyptiacus and A. versicolor. It included the inability to produce base either from sodium citrate or lactic acid media, growth at 45 degrees C (thermophilicity), and production of very similar pigmentations on Aspergillus flavus and parasiticus agar. A. egyptiacus is therefore better placed in the Aspergillus nidulans-Emericella assemblage.

Enzymatic activity profiling as a potential biotyping method for Ajellomyces dermatitidis

Enzyme profiling was investigated as a means of recognizing biotypes and individual strains of Ajellomyces dermatitidis (anamorph, Blastomyces dermatitidis). Eighteen North American and 2 African representatives were tested with the Yeast-IDENT enzymatic activity profiling system (Analytab Products, Plainview, N.Y.). Significant variation was found between isolates, particularly in beta-galactosaminidase activity.