RESUMO
An endophytic species of Micrococcus was isolated from Aloe vera leaf (syn. Aloe barbadensis) and screened for protease production with five other species of Micrococcus. Data indicated that endophytic Micrococcus aloeverae AE-6 MCC 2184T and Micrococcus yunnanensis DSM 21948T showed efficient protease production potential and secreted active protease at high salt (10%), temperature (40 °C) and in wide range of pH 8-10. Unlike M. yunnanensis DSM 21948T, protease production by M. aloeverae AE-6 MCC 2184T was stringently controlled by pH. Protease induction study using different group of peptides, peptide carbohydrates and peptide macronutrient combinations showed variable response with both the organisms. Result indicated that the amount of protease was not directly related to cell biomass but it depends on nature of inducible peptides. In this study we also developed a modified agar-well assay for semi-quantitative data from large number of replicates.
RESUMO
A yellow Gram-stain-positive, non-motile, non-endospore -forming, spherical endophytic actinobacterium, designated strain AE-6(T), was isolated from the inner fleshy leaf tissues of Aloe barbadensis (Aloe vera) collected from Pune, Maharashtra, India. Strain AE-6(T) grew at high salt concentrations [10% (w/v) NaCl], temperatures of 15-41 °C and a pH range of 5-12. It showed highest (99.7%) 16S rRNA gene sequence similarity with Micrococcus yunnanensis YIM 65004(T) followed by Micrococcus luteus NCTC 2665(T) (99.6%) and Micrococcus endophyticus YIM 56238(T) (99.0%). Ribosomal protein profiling by MALDI-TOF/MS also showed it was most closely related to M. yunnanensis YIM 65004(T) and M. luteus NCTC 2665(T). Like other members of the genus Micrococcus, strain AE-6(T) had a high content of branched chain fatty acids (iso-C15:0 and anteiso-C15:0). MK-8(H2) and MK-8 were the predominant isoprenoid quinones. Cell wall analysis showed an 'A2 L-Lys-peptide subunit' type of peptidoglycan and ribose to be the major cell wall sugar. The DNA G+C content was 70 mol%. Results of DNA-DNA hybridization of AE-6(T) with its closest relatives from the genus Micrococcus produced a value of less than 70%. Based on the results of this study, strain AE-6(T) could be clearly differentiated from other members of the genus Micrococcus. We propose that it represents a novel species of the genus Micrococcus and suggest the name Micrococcus aloeverae sp. nov., with strain AE-6(T) ( = MCC 2184(T) = DSM 27472(T)) as the type strain of the species.
