title: Characterization of an extremely salt-tolerant and thermostable phytase from Bacillus amyloliquefaciens US573.
abstract: The extracellular phytase produced by the Bacillus amyloliquefaciens US573 strain, isolated from geothermal soil located in Southern Tunisia was purified and characterized. This calcium-dependent and bile-stable enzyme (PHY US573) was optimally active at pH 7.5 and 70 °C. It showed a good stability at pH ranging from 4 to 10, and especially, an exceptional thermostability as it recovered 50 and 62% of activity after heating for 10 min at 100 and 90 °C, respectively. In addition, PHY US573 was found to be extremely salt-tolerant since it preserved 80 and 95% of activity in the presence of 20 g/l of NaCl and LiCl, respectively. The gene corresponding to PHY US573 was cloned. It encodes a 383 amino acids polypeptide exhibiting 99% identity with the highly thermostable phytases from Bacillus sp. MD2 and B. amyloliquefaciens DS11 (3 and 5 residues difference, respectively), suggesting the existence of common molecular determinants responsible for their remarkable heat stability. Overall, our findings illustrated that in addition to its high potential for application in feed industry, the salt tolerance of the PHY US573 phytase, may represent an exciting new avenue for improvement of phosphorus-use efficiency of salt-tolerant plants in soils with high salt and phytate content.
authors.affiliation: Laboratoire de Microorganismes et de Biomolécules (LMB), Centre de Biotechnologie de Sfax, Université de Sfax, Route de Sidi Mansour Km 6, BP "1177" 3018 Sfax, Tunisia.
authors.forename: Ines
authors.initials: I
authors.lastname: Boukhris
authors.affiliation: Laboratoire de Microorganismes et de Biomolécules (LMB), Centre de Biotechnologie de Sfax, Université de Sfax, Route de Sidi Mansour Km 6, BP "1177" 3018 Sfax, Tunisia.
authors.forename: Ameny
authors.initials: A
authors.lastname: Farhat-Khemakhem
authors.affiliation: Laboratoire de Microorganismes et de Biomolécules (LMB), Centre de Biotechnologie de Sfax, Université de Sfax, Route de Sidi Mansour Km 6, BP "1177" 3018 Sfax, Tunisia.
authors.forename: Monia
authors.initials: M
authors.lastname: Blibech
authors.affiliation: Laboratoire de Microorganismes et de Biomolécules (LMB), Centre de Biotechnologie de Sfax, Université de Sfax, Route de Sidi Mansour Km 6, BP "1177" 3018 Sfax, Tunisia.
authors.forename: Kameleddine
authors.initials: K
authors.lastname: Bouchaala
authors.affiliation: Laboratoire de Microorganismes et de Biomolécules (LMB), Centre de Biotechnologie de Sfax, Université de Sfax, Route de Sidi Mansour Km 6, BP "1177" 3018 Sfax, Tunisia. Electronic address: hichem.chouayekh@cbs.rnrt.tn.
authors.forename: Hichem
authors.initials: H
authors.lastname: Chouayekh
mesh_terms: D010832:6-Phytase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology* / Q000235:genetics; D002118:Calcium / Q000737:chemistry; D003001:Cloning, Molecular; D004789:Enzyme Activation; D004795:Enzyme Stability; D005110:Extracellular Space / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D055049:Salt Tolerance / Q000235:genetics; D016415:Sequence Alignment; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D010832:6-Phytase; D002118:Calcium
keywords: Animal feed; Bacillus amyloliquefaciens US573; Extreme salt tolerance; High thermostability; Phosphorus nutrition; Phytase