Antarctic marine bacterium Pseudoalteromonas sp. KNOUC808 as a source of cold-adapted lactose hydrolyzing enzyme

Abstract

SPsychrophilic bacteria, which grow on lactose as a carbon source, were isolated from Antarctic polar sea water. Among the psychrophilic bacteria isolated, strain KNOUC808 was able to grow on lactose at below 5ºC, and showed 0.867 unit of o-nitrophenyl -D-galactopyranoside(ONPG) hydrolyzing activity at 4ºC.The isolate was gram-negative, rod, aerobic, catalase positive and oxidase positive. Optimum growth was done at 20ºC, pH 6.8-7.2. The composition of major fatty acids in cell of KNOUC801 was C 12:0 (5.48%), C 12:0 3OH (9.21%), C 16:0 (41.83%), C 17:0 8 (7.24%) and C 18:1 7 (7.04%). All these results together suggest that it is affiliated with Pseudoalteromonas genus. The 16S rDNA sequence corroborate the phenotypic tests and the novel strain was designated as Pseudoalteromonas sp. KNOUC808. The optimum temperature and pH for lactose hydrolyzing enzyme was 20ºC and 7.8, respectively. The enzyme was stable at 4ºC for 7 days, but its activity decreased to about 50% of initial activity at 37ºC in 7 days.

Phylogenetic analysis and biological characteristic tests of marine bacteria isolated from Southern Ocean (Indian sector) water

“…The gram negative bacteria Pseudoalteromonas sp. was previously isolated from Antarctic water and its best growth was observed at 20°C (Nam and Ahn, 2011). Current data supports earlier reports (Neufeld et al, 2004;Steven et al, 2007;Shivaji et al, 2013) that phylum proteobacter are common in cold habitats.…”

Psychrophiles: Ecological significance and potential industrial application

“…It can be used to produce lactosefree milk-derived foods for lactose-intolerant people, who represent approximately 30% of the world population. 83 Furthermore, it can be used to convert lactose in whey to D-tagatose -a natural high-addedvalue sweetener with low caloric and glycemic index. 63 Hoyoux et al 84 patented a cold-active β-galactosidase from an Antarctic psychrophile, Pseudoalteromonas haloplanktis, for its capacity to hydrolyse lactose during milk storage at low temperatures.…”