Aims:To isolate an antagonist for use in the biological control of phytopathogenic fungi including Colletotrichum gloeosporioides, then to purify and characterize the biocontrol agent produced by the antagonist. Methods and Results: Bacteria that exhibited antifungal activity against the causative agent pepper anthracnose were isolated from soil, with Bacillus thuringiensis CMB26 showing the strongest activity. A lipopeptide produced by B. thuringiensis CMB26 was precipitated by adjusting the pH 2 with 3 N N HCl and extracted using chloroform/ methanol (2 : 1, v/v) and reversed-phase HPLC. The molecular weight was estimated as 1447 Da by MALDI-TOF mass spectrometry. Scanning electron and optical microscopies showed that the lipopeptide has activity against Escherichia coli O157:ac88, larvae of the cabbage white butterfly (Pieris rapae crucivora) and phytopathogenic fungi. The lipopeptide had cyclic structure and the amino acid composition was LL-Pro, and L L-Ile in a molar ratio of 3 : 1 : 2 : 1 : 1 : 2 : 1 : 1. The purified lipopeptide showed the same amino acid composition as fengycin, but differed slightly in fatty acid composition, in which the double bond was at carbons 13-14 (m/z 303, 316) and there was no methyl group. Conclusion: A lipopeptide was purified and characterized from B. thuringiensis CMB26 and found to be similar to the lipopeptide fengycin. This lipopeptide can function as a biocontrol agent, and exhibits fungicidal, bactericidal, and insecticidal activity. Significance and Impact of the Study: Compared with surfactin and iturin, the lipopeptide from B. thuringiensis CMB26 showed stronger antifungal activity against phytopathogenic fungi. This lipopeptide is a candidate for the biocontrol of pathogens in agriculture.

In this study, the effect of mineral fertilizer and organic manure were evaluated on soil microbial biomass, dehydrogenase activity, bacterial and fungal community structure in a long-term (33 years) field experiment. Except for the mineral nitrogen fertilizer (N) treatment, long-term fertilization greatly increased soil microbial biomass carbon (SMBC) and dehydrogenase activity. Organic manure had a significantly greater impact on SMBC and dehydrogenase activity, compared with mineral fertilizers. Bacterial and fungal community structure was analyzed by polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). Long-term fertilization increased bacterial and fungal ribotype diversity. Total soil nitrogen (TN) and phosphorus (TP), soil organic carbon (SOC) and available phosphorus (AP) had a similar level of influence on bacterial ribotypes while TN, SOC and AP had a larger influence than alkali-hydrolyzable nitrogen (AHN) on fungal ribotypes. Our results suggested that long-term P-deficiency fertilization can significantly decrease soil microbial biomass, dehydrogenase activity and bacterial diversity. N-fertilizer and SOC have an important influence on bacterial and fungal communities.Electronic supplementary materialThe online version of this article (doi:10.1007/s13213-014-0889-9) contains supplementary material, which is available to authorized users.

In this study, β-1, 4-endoglucanase from Penicillium simplicissimum H-11 was purified to homogeneity using ammonium sulfate followed by Sephadex G-100 chromatography. The purity of the enzyme was confirmed by HPLC and 12% SDS-PAGE, indicating a single peak with a molecular mass of 33.2 kDa. This protein had mostly α-helix structures, as confirmed by FTIR spectrometry. The optimum pH and temperature were 3.2 and 60 °C with pH stability of 2.8~5.6 and temperature stability of 50 °C for 12 h and 4 h, respectively. A metal profile of the enzyme showed that Mg 2+ and Sn 2+ were strong activators, while Cu 2+ was a strong inhibitor. An interesting feature of this enzyme is that it can effectively hydrolyze microcrystalline cellulose, filter paper, and CMC-Na, thus revealing both endo-and exo-glucanase features of the enzyme. The kinetic constants K m and V max were 14.881 mg/mL and 0.364 mg/mL/min, respectively, against CMC-Na as a substrate.

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