Environ Exp Biol (2016) 14: 173–181

Screening cabbage rhizosphere as a habitat for isolation of phosphate-solubilizing bacteria

Abstract

Phosphorus plays a major role in plant growth, but due to insoluble complex formation in soil, it is mainly unavailable for plants. Phosphate solubilizing bacteria dissolve phosphate and hence are regarded as biofertilizer. These bacteria are present in different habitats and screening of such habitats can introduce potent phosphate solubilizing bacteria as biologic fertilizer. The aim was finding such isolates from cabbage rhizosphere. Soil samples were enriched and screened using Pikovskaya’s agar. Isolates were identified by phenotypic and genotypic methods. Their biological activities were also investigated. Four of these isolates had highest phosphate solubilization index (1.3 to 4.7) and phosphate solubilization efficiency (33.3 to 366.6). Inorganic phosphate solubilizing ability of these strains was 6.74 to 89.1 mg L^–1. The predominant organic acid found was oxalic acid for RK33 isolate. All phosphate solubilizing strains were able to fix nitrogen, while only RK24 and RK33 produced phytase. These isolates were Aeromonas sp., Proteus sp., Proteus mirabilis and Raoultella terrigena. Finally, it can be concluded that cabbage rhizosphere is a potent habitat for finding phosphate solublizing bacteria, which can be applied as biofertilizer, thus avoiding undesirable side effects of chemical fertilizers.