TWO NOVEL CLUSTERS OF NOCARDIOPSIS RECOVERED FROM HALOALKALINE ENVIRONMENT: POTENTIAL RESOURCE OF MULTI-ADVANTAGEOUS LIPASES

Abstract

Wadi El Natrun district in the northwest of Cairo, Egypt, represents a highly stable unique ecology containing dual stress of salinity and alkalinity. Bioprospecting lipase producers in such an environment helps in finding enzymes of novel properties. Seven Nocardiopsis strains were recovered from Wadi El Natrun region, and their distribution within the phylogeny of the genus showed a particular pattern of two clusters descending from two evolutionary lineages. All strains produced highly alkaline lipase (optimum pH: 9- 11) in different amounts. The principal features of lipases from all strains, not only from the most potent one, were realized in a comparative profile to prospect more of their possible advantages in industrial biocatalysis. Most of the lipases were thermophilic; the optimum temperature was 50-55°C in lipases from five isolates. Activation energy of all lipases varied considerably between 5.52 and 13.58 Kcal/mole. WN4L lipase exhibited the highest thermal stability (half-life time=99 min at 70°C). Interestingly, different lipases exhibited good stabilities in water-immiscible organic solvents which highlighted their suitability in the two-partitioning system applications. A general prospect about characteristic features of Wadi El Natrun lipases was realized; they share the multi-advantages of high alkalophilicity, tendency to be thermophilic, and readiness to work in acetone and water-immiscible solvents. Considering the extensive variation, each lipase appeared of a unique profile that enables to choose the most compatible one according to the specific circumstances of the interested industrial process. Moreover, a cocktail enzyme preparation of such lipases could be used as a multi-task lipase formula.