Isolation and identification of molds in Hubei cigar tobacco and screening of antagonistic strains of Bacillus spp.

In order to screen Bacillus spp. that can efficiently antagonize molds in Hubei cigar tobacco, using a combination of morphological and molecular biological strain identification methods, five molds were isolated and purified from cigar tobacco in Shiyan and Yichang, Hubei Province. They were identified as Aspergillus sydowii, Penicillium chrysogenum, Talaromyces funiculosus, Trichoderma Yunnanense, and Aspergillus niger. The five molds were used to back-infect the cigar tobacco, and it was found that the cigar tobacco before fermentation in Yichang was more susceptible to infection by the spore suspension mixed with the five kinds of molds, and Talaromyces funiculosus and Aspergillus niger had strong mildew-causing properties to the cigar tobacco. The Oxford cup inhibition method was used to analyze the antagonistic ability of different antagonistic strains of Bacillus spp. against the molds, among which Bacillus amyloliquefaciens DY-9 was the strongest antagonist against each of the molds. At a concentration of 10⁹ CFU/mL, strain DY-9 suspension had the best anti-mold effect on the cigar tobacco.