Growth Response and Protein Profile of Region Specific Rhizobium Strains Isolated from Vigna mungo from Different Localities of Odisha State, India at Different Temperature, pH, Salinity and Iron

Abstract

Six strains of Rhizobium were isolated from Vigna mungo and their growth response to various environmental variables like different temperatures, pH, salinity (NaCl) and iron (Fe-citrate) was studied. Rhizobium sp.UU-25 was the most tolerant species to high (45o C) and low temperature (4o C), high salinity concentration (0.5M) but was sensitive to lower pH (pH 5). Rhizobium sp. UU-24 also grew at a wider temperature range (45o C to 4o C) alkaline pH (pH 10) and at higher concentration of iron (250 μg/ml) but was the very sensitive to a little increase in salinity. UU-27 grew at lower pH (pH 4), non-saline conditions and low iron concentration of 10 μg/ml in the media. UU-28 grew well only in the presence low iron (10 μg/ ml) and was sensitive to lower temperature (4o C) and acidic pH (pH 5) of the media. Rhizobium strain UU-23 was most sensitive to higher temperature (35o C), alkaline pH (pH 10), but was tolerant to higher level of salinity (1M). Based on their growth response to these stresses the Rhizobium strains UU-23, UU-25 and UU27 were selected to study the modification of their protein pattern upon exposure to all these stresses for 72h. Absence of NaCl in the medium lead to over production of a 130 KDa protein in all the three Rhizobium strains and also of one chaperonin (67 kDa protein) in the strain UU-25 and UU-27 was detected. In addition, one 45 kDa protein was repressed and one 62 kDa protein was over produced in these three organisms when exposed to 100 μg/ml or above concentration of Fe-citrate.