title: Growth and pectinase production by Aspergillus Mexican strain protoplast regenerated under acidic stress.
abstract: Protoplasts from Aspergillus sp. FP-180 and Aspergillus awamori NRRL- 3112 were released and regenerated at extreme acidic conditions. The best conditions for protoplast release were 0.8 M KCI, pH 5.8, and 3 h of digestion using mycelia from 12- to 16-h cultures from either Aspergillus sp. FP-180 or A. awamori NRRL-3112. The addition of fresh mycelia to an ongoing digestion after 1 h increased protoplast 4.5-5 times. A regeneration efficiency of 90% was attained at pH 6.0, and it was possible to regenerate protoplasts at pH 1.7 with a regeneration efficiency of 0.5% for Aspergillus sp. FP-180. The LpH-10 strain, derived from protoplast from Aspergillus sp FP-180, was able to regenerate at pH 1.7 and grow at pH values as low as 1.5, values at which the original strain is unable to grow. Regeneration at extreme pH improved the performance of LpH-10 strain. It showed a twofold increase in cell growth at pH 2.0 in liquid culture and a higher pectinolytic activity in relation to that produced by the original strain.
authors.affiliation: Laboratory of Fungal Physiology, Department of Food Science and Biotechnology, Faculty of Chemistry, Química E, National University of Mexico, UNAM, CP 04510, México DF, México.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Peraza
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Ortiz
authors.forename: John F
authors.initials: JF
authors.lastname: Peberdy
authors.forename: Guillermo
authors.initials: G
authors.lastname: Aguilar
mesh_terms: D000143:Acids; D000681:Amylases / Q000032:analysis / Q000096:biosynthesis; D001230:Aspergillus / Q000201:enzymology* / Q000254:growth & development / Q000648:ultrastructure; D003470:Culture Media; D006863:Hydrogen-Ion Concentration; D008800:Mexico; D025282:Mycelium; D011096:Polygalacturonase / Q000032:analysis / Q000096:biosynthesis*; D011523:Protoplasts / Q000502:physiology* / Q000648:ultrastructure; D012038:Regeneration; D013696:Temperature; D013997:Time Factors; D014995:Xylosidases / Q000032:analysis / Q000096:biosynthesis
chemical_list: D000143:Acids; D003470:Culture Media; D000681:Amylases; D014995:Xylosidases; D011096:Polygalacturonase