Abstract:

In order to explore bioantisepsispreservation agents of fruits, inhibition effect of Bacillus subtilis to rot pathogen of blood orange and bioantisepsispreservation of B. subtilis preparation were investigated. Three effective bacteriostatic compositions were found in B. subtilis through the paper chromatography and the gel filtration chromatography. Two of them were big molecular weight substance with small quantity, while the orther was small molecular weight with a great amount. They had different bacteriostasis to the fungus of blood orange fruit. Alternaria spp. was sensitive to all the three components, while Penicillium spp. was sensitive to component Ⅱ and Ⅲ, which suggested that the antibiotic effect of the broadspectrum antagonistic microorganism had some selectivity. Biopreservation experimentation showed that the higher concentration of B. subtilis powder had better antiseptic effect, and protected fruits from dehydration. When the powder was diluted 20-100 times, the relative control effect decreased from 15.2% to 7.4%. Generally, the effect was better with 1-10 times dilution. Heating treatment could decrease the antiseptic effect of the components by 33.6%, however, the effect would increase 28.2% when aspirin was mixed with B. subtilisagents. Treatment time with the bioagents also had influence on the antiseptic effect. Within eight hours, the longer treatment time the better control effect. Generally treatment for 4-8 hours was the best. If biopowder combined preservation technique the control effect would enhance further. Rate of fruit weight loss would decrease and the edibility would increase, and the control effect would be comparable to 2,4-D, sportak and guoguang.

Key words: blood orange, biocontrol, Bacillus subtilis, plant disease, preservation