Purpose Monascus pigment was widely applied in food processing industry as functional additive, so more attention was paid to the fermentation optimization of pigment production. Therefore, this paper aims to evaluate the best possible fermentative conditions for maximum production of biopigment using submerged fermentation (SFM) and solid state fermentation (SSF) by Monascus purpureus HBSD 08. Design/methodology/approach The biopigment was produced by using an SMF and an SSF with optimized substrate to achieve higher yield. The antioxidant activity was evaluated by DPPH radical scavenging ability, superoxide anion radical scavenging ability and hydroxyl radical scavenging ability. The pigment composition was analyzed by thin layer chromatography. Findings Maximum Monascus pigment production (79.6 U/ml and 1,102 U/g) were obtained under an SFM and an SFF. The antioxidant activity of the pigment in an SFM was significantly higher than that in an SFM. The composition of pigment was not different in an SFM and an SFF. Originality/value The study developed new conditions, and Monascus strain was a candidate for producing pigment in an SFM and an SFF. To the authors’ best knowledge, this is a first attempt toward comparative evaluation on antioxidant capacity and composition between pigment in an SSF and an SFM. This result will serve for Monascus pigment production.

Bacteriocins have attracted increasing interest because of their potential as natural preservatives. Recent studies showed that the Bacillus cereus group is a prominent producer of bacteriocins. Using a laboratory-based screening strategy, we identified a strain in the B. cereus group, B. toyonensis XIN-YC13, with antimicrobial activity against B. cereus. A novel, 70-amino acid-long leaderless bacteriocin, toyoncin, was purified from the culture supernatant of strain XIN-YC13 and its molecular mass was found to be 7817.1012 Da. Toyoncin shares no similarity with any other known bacteriocins, and its N-terminal amino acid is formylmethionine rather than methionine. Toyoncin shows good pH and heat stability and exhibits specific antimicrobial activity against two important food-borne pathogens, B. cereus and Listeria monocytogenes. Additionally, toyoncin exerts bactericidal activity and induces cell membrane damage. Toyoncin can also inhibit the outgrowth of B. cereus spores. The preservation assays showed that toyoncin effectively suppressed or eradicated B. cereus and L. monocytogenes in pasteurized skim milk. These results suggest that toyoncin can be used as a new bio-preservative against B. cereus and L. monocytogenes in the food industry. Importance: We identified a novel leaderless bacteriocin, toyoncin, produced by B. toyonensis XIN-YC13. Toyoncin shows good pH and heat stability; has specific antimicrobial activity against, B. cereus and L. monocytogenes (two important food-borne pathogens), and destroys their cell membrane integrity. Toyoncin inhibited the outgrowth of B. cereus spores and effectively inhibited or eliminated B. cereus and L. monocytogenes in a milk model system. These results indicate the potential of toyoncin as a food preservative.

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Maximum catalase production by mesophilic bacterium Serratia marcescens SYBC-01 was obtained by an optimization of culture medium and conditions. A novel cold-adapted catalase from the strain was purified and characterized. The Cat-2 without peroxidase activity was a homodimer with a molecular mass of 154 kDa, consisting of two identical subunits of about 70 kDa. Its apparent K m and V max value were 29.7 mM and 80,925 U/ mg of protein, respectively. The Cat-2 exhibited maximal activity at pH 7.0, being relatively stable in alkaline conditions. The enzyme was most active at approximately 20°C and had 73.8% activity at 0°C. After incubation at 60°C for 60 min, the enzyme still maintained 75% of its initial activity. The Cat-2 displayed relatively higher thermostability compared to that of other cold-adapted and some mesophilic catalases.