Abstract:

A strain BSi20414 with higher β-galactosidase activity was isolated from Arctic sea ice. Based on its Physiological and biochemical characteristics and 16S rDNA sequence, it was identified as Marinomonas sp. BSi20414. A series of the detail experiments on the conditions of β-galactosidase production were conducted and the results showed that the optimal fermentation conditions for enzyme production were: 30℃，1.5% (w/v) lactose, initial pH 7.0，Inoculum amount 3%，80 mL fermentative medium in 500 mL flask, 180 rpm for 96 hrs. Under these conditions, the enzyme activity of 1.01 U / mL in the second screening stage increased to 2.92 U / mL. Preliminary experiments showed that the optimal reaction temperature of the crude enzyme on ONPG substrate was 60 ℃. This Result suggested that this cold adapted strain Marinomonas sp. BSi20414 may be have a characteristic of producing high-temperature enzyme.

Key words: fermentation conditions