Effect of some plant extracts on growth and enzyme activities of soft rot bacteria

ABSTRACT

The water - soluble extracts prepared from com foliage, soybean seeds, cotton foliage and anise seeds inhibited growth of soft rot bacteria. At higher concentrations, 78 mg, 32mg, 80mg and 67 mg dry weight / ml of corn, soybean, cotton and anise extracts respectively the bacterial cells were killed. Moreover, isolated varied greatly in their sensitivity to the substances present in soybean and anise extracts. When the crude extract of soybean seeds was added to the growth medium of E. carotovora subsp. carotovora its population was substantially checked and consequently its total pectolytic and cellulolytic enzyme activities decreased, but not as sharp as its growth. Thus, when the activity was calculated on basis of a constant number of bacterial cells [108 / ml], it appeared that the extract enhanced these enzyme activities. In addition polyphenoloxidase activity of E. carotovora subsp. carotovora was affected by the soybean seed extract almost similarly as in case of pectolytic and cellulolytic enzymes. Contrary to the results obtained with the above enzymes, soybean seed extract supplemented to the growth medium of E.C. subsp. carotovora isolates either strongly or completly inhibited their peroxidase activity