Isolation of Rhizobia from Species of Legumes Plants and Utilizing them in Ploy-β-Hydroxybutyrate Production (PHB)

Abstract

Thirty-eight rhizobia isolates were obtained from legume species included: Medicago sativa, M. littoralis, Vicia faba, Lupinus varius, Cicer arietinum, Arachis hypogaea, Vigna unguiculata and Pisum sativum. They were collected from different regions of Libya with arid and semi-arid climate. The All-Rhizobia isolates were able to form effective symbiosis with their hosts. Isolates grown on yeast extract and mannitol medium were primary screened for their ability to produce polyhydroxybutyrate on the basis of staining with Sudan black B. Different sources of carbon and nitrogen were added to the yeast extract and mannitol medium. The growth of isolates varied in using these media where the Yeast extract and mannitol supplemented with 2.5 g of Tryptone and Peptone was the best medium to support the growth of the isolates. Temperature and pH have not had a significant effect on the ability of isolates to produce polyhydroxybutyrate. The moderate and slow growing isolates, especially RVF1b, RC1b, RC3 and RVG5 were superior in the producing of the polyhydroxybutyrate under all conditions compared to the other isolates, while the isolate RP4 was the least productive. The producing polyhydroxybutyrate in this study have not shown any toxic effect on human blood, as no clotting has occurred after one hour of incubation.