To investigate the effect of fungal elicitors on biosynthesis of natamycin in the cultures of Streptomyces natalensis HW-2, the biomass and filtrate of the broth from Aspergillus niger AS 3.6472, Penicillium chrysogenum AS 3.5163, A. oryzae AS 3.2068, and Saccharomyces cerevisiae AS 2.2081 were used to induce natamycin production in S. natalensis HW-2. The results showed that the biomass of P. chrysogenum AS 3.5163 could enhance the yield of natamycin from 0.639 to 0.875 g l(-1). The elicitor from the fermentation broth of P. chrysogenum AS 3.5163 showed the highest inducing efficiency with the yield of natamycin enhanced from 0.632 to 1.84 g l(-1). The elicitor that was cultured for 2 days showed the strongest inducing activity during the fermentation of S. natalensis HW-2 for 24 h, and the yield of natamycin was enhanced from 0.637 to 2.12 g l(-1). The biochemical parameters were examined at the end of fermentation and the results demonstrated that both the growth of cells and the concentration of residual sugar could be influenced. The residual sugar decreased from 5.03 to 4.27 g l(-1), and the biomass decreased from 10.26 to 6.87 g l(-1). Finally, the elicitor was identified as a low molecular weight substance with a similar polarity to that of butyl alcohol by primary qualitative analysis.

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A new strain of Bacillus coagulans CGMCC 9551, which has a broad range of antibacterial activities against six main pathogenic bacteria including Escherichia coli O8, Staphylococcus aureus, Salmonella enterica subsp. enterica serovar enteritidis, Streptococcus suis, Listeria monocytogenes and Pasteurella multocida, was isolated from healthy piglet feces. In adhesion assay, the isolate exhibited a stronger adhesion to pig intestinal mucus than that of B. subtilis JT143 and L. acidophilus LY24 respectively isolated from BioPlus(®)2B and FloraFIT(®) Probiotics (P < 0.05). The adhesion activity reached 44.5 ± 3.2, 48.9 ± 2.6, 42.6 ± 3.3 and 37.6 ± 2.4% to jejunum, ileum, transverse colon and sigmoid colon, separately. The survival rate of B. coagulans CGMCC 9551 was reduced by only 20% at 4 h exposure under 0.9% w/v bile salt. The strain was fully resistant to pH 2 for 2 h with 90.1 ± 3.5% survival and susceptible to 15 antibiotics commonly used in veterinary medicine. Additionally, the bacteria showed amylase, protease and cellulase activities. The safety assessment demonstrated the lack of toxicity potential in B. coagulans CGMCC 9551 by ligated rabbit ileal loop assay, acute and subchronic toxicity test. These results implied that that the new strain of B. coagulans CGMCC 9951 isolated from healthy piglet feces has promising probiotic characteristics and offers desirable opportunities for its successful commercialization as one excellent candidate probiotic.

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This review builds universal design rules for the antibacterial regulation of nanomaterials.

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The effects of fungal elicitor on the physicochemical and microbial responses of Streptomyces natalensis HW-2 were investigated. The results showed that the elicitor could decrease dry cell weight (DCW) by 17.7% and increase the utilization of glucose, while the curve of pH was not obviously altered. The elicitor enhanced the yield of natamycin from 1.33 to 2.49 g/L. The morphology of the colony and the mycelium treated with elicitor showed significant differences from that of control. The level of intracellular reactive oxygen species (ROS) increased to 333.8 ng/L, which was a twofold increase comparing with the control. The concentration of Ca reached 421.1 nmol/L, which increased by 32.8% after the addition of the elicitor. The activities of pyruvic carboxylase and phosphoenol pyruvate carboxylase were enhanced by 27.8 and 11.9%, respectively, while citrate synthase activity decreased by 23.1% in comparison with the control.

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