The genus Clostridium is a Gram-positive, spore-forming bacterium. Most species of Clostridium spp. usually are found in soil, water, dead plants, animal carcasses, and play an important role in the decomposition of substances in nature. Raw meat and fresh vegetable are more likely to be contaminated with spores or vegetative cells of the genus Clostridium. The study results showed that the percentage of samples contaminated with raw meat and leafy vegetables collected at markets in Dong Da, Ha Dong and Hoang Mai districts infected with C. perfringens was 26.67% (n = 150) and 26.82% (n = 220). The percentage of raw meat and leafy vegetable samples contaminated with C. difficile was very low with 6.00% (n = 150) and 0.9% (n = 220), respectively. Gene amplification reactions revealed the presence of cpa toxin gene in all C. perfringens strains and detected 02 C. difficile strains carrying the tcdA gene.

Strawberries are economically important owing to their unique flavour, health benefits, and nutritional aspects. Decay after harvest is a major issue in the development of strawberry industry. Currently, the most effective method for controlling decay after harvest is storage of strawberries at low temperature combined with usage of chemical fungicides. However, long-term usage of chemical fungicides not only causes pathogen resistance but also is harmful for human health and environment. Biocontrol method for the management of disease after strawberry harvest has great practical significance. In this study, totally 200 bacterial strains isolated from the surface of healthy strawberry fruit were tested for antagonistic activity against five fungal pathogens. Among them, VK199 strain was potent against all five postharvest spoilage fungi on strawberry fruit and then utilized for further study. This strain was identified as Bacillus siamensis based on sequence analysis of 16S rDNA. The extracellular lytic enzymes, including cellulase, amylase, protease and chitinase released by B. siamensis VK199 were detected. Furthemore, in vivo, the results of biological control efficacy test showed that B. siamensis VK199 suppressed the occurrence of diseases caused by Botrytis cinerea, Colletotrichum gloeosporioides, Mucor nidicola and Rhizopus delemar of strawberry during storage.