Isolation and Characterization of Two Halophilic Bacillus (B. licheniformis and Bacillus sp) with Antifungal Activity

Abstract

New bacterial strains of Bacillus licheniformis and sp were isolated from the rhizosphere of potato, in front of the sea (Bejaia, Algeria). Strains were identified by phenotypic analyses: Gram s taining, mobility, catalase, oxidase, form of colony and cell morphology. Metabolic characters such carbon source, sugars, organic acids, aerobic/anaerobic respiratory system are revealed by API system 50CHB/E. The 16SrRNA gene was isolated and sequenced (1500 bp), and the phylogenic tree was established (bootstrap method). The first strain (RBA-E23) showed a very high similarity to Bacillu s licheniformis (DQ082997.1) (98%) and B. licheniformis (AF372616.1), but the second (RBA-E32) is classified as the out-gro up. Strains are halotolerants 300 and 400 mM/l NaCl, respectively. They used glycine betaine and proline as synthetic osmoprotectants, and marine algal extracts of Ulva lactucaas natural osmoprotectant. The two strains produce: high amount of auxine-phytohormone (IAA: 78 and 101 mg/l); different enzymes such as: cellulase, chitinase, protease, lipase, amylase and urease; siderophores and solubilize ino rganic phosphorus. The study of antifungal strains activity toward nine phyto pathogenic fungi Verticillium dahlia, Fusarium oxysporum, Botryotinia fuckiliana, Phytophthor a cinamomi, Phytophthora cactorum, Colletotrichum acutatum, Botrytis cinerea, Aspergillus Niger and Aspergillus flavus, shows an interesting inhibition activity with variable percentage of Growth inhibition (PGI %) against phytopathogens. Both of bacteria displayed more benefic characters, while the enzymes can be involved in the organic matter decomposition; utilization of the phytohormone-IAA as simulator of vegetable growth. Siderophores and phosphate solubilization are interesting in the fe rtilization of soil. Finally, strains could have potential application against phytopathogenic fungi.