[Isolation and identification Alicyclobacillus from concentrated apple juice processing].

The forty-five strains of bacteria have been isolated from concentrated apple juice. All of them can grow at K agar (pH 4.0), but can't grow at LB palate (pH 7.0). By using heat resistance test, 38 strains of these bacteria could be classified into 3 groups according to their spore-forming time. 33 strains of them had the same spore-forming time as DSM 3922, which could produce spores within 48 h when cultivated at 45 degrees C; 3 strains of them could grow very fast and produced spores within 17 h; and 3 strains of them produced spores 48h later. Based on the results of 16S rDNA PCR-RFLP analysis, 7 strains of unknown, probably new species and 5 reference strains were selected for 19 phenotypic characteristics test and the result were analyses by UPGMA. The results of phenotypic characteristics test had good agreement with 16S rDNA PCR-RFLP analyses, that the 7 strains were different from all the 5 reference strains, they are new species of Alicyclobacillus.

Isolation and characterization of thermo-acidophilic endospore-forming bacteria from the concentrated apple juice-processing environment.

Forty-five thermo-acidophilic, spore-forming bacteria were isolated from a concentrated apple juice-processing environment. All of them were Gram-positive, rod shaped, and strictly aerobic that most likely belong to the genus of Alicyclobacillus. A fast identification method-16S rDNA PCR-RFLP was used to identify them. The results indicated that at the similarity level of 87%, apple juice isolates strains of 1-4 and 1-2-4 clustered with the reference strain of A. acidoterrstris DSM 3922T, and 4-2-1, S-22 and 5-1 with A. cycloheptanicus DSM 4006T, respectively. The other tested strains were different from all the reference strains in this study and may be new species of Alicyclobacillus genus or the other. In order to confirm this conclusion, we selected 7 16S rDNA PCR-RFLP identified strains and 5 type strains of Alicyclobacillus genus, carried on 51 kinds of phenotypic characteristics and analysis the data by unweighted pair group method with arithmetic mean (UPGMA). The results showed that the similarity degree between every two strains was lower than 80%. It also suggested that they may be different from each other and the unidentified strains may be new species. In addition, spoilage effects of them on 12 Brix apple juice were also studied. The result suggested that all 19 tested bacterial strains caused apple juice to become turbid, form a precipitate and off odor at varying rates when incubated at 37 degrees C up to 12 days. It suggested that these bacteria are associated with the spoilage of apple juice during storage.