Strain improvement in lignocellulolytic mutants of P. ostreatus by protoplast fusion

Vijaya, M.A. Singaracharya, M. Vijaya Lakshmi and R. Mallikarjuna Reddy

Adv Bio Tech, vol.10, no.07, 07-11, January 2011

ABSTRACT

Protoplast fusion technology, a viable option for strain improvement in higher basidiomycetes was applied for further and stable improvement in the lignolytic activities of a white-rot fungus Pleurotus ostreatus. The two mono-caryotic parent strains of P. ostreatus – POM1 (U.V.irriadiated mutant) and POM2 – (X-ray irradiated mutant) were isolated and used for protoplast isolation and fusion. The amounts of protoplasts obtained in POM1 and POM2 were 4.59 x 106 and 4.65 x 106 protoplasts/ml respectively. Among the 357 colonies isolated after protoplast fusion only 3 possessed clamp connections and chosen as fusants (POFU1, POFU2 and POFU3). Of the three fusants POFU2 showed maximum growth rate on malt extract agar plates incubated at room temperature. In malt extract broth after 14 days of incubation the maximum enzyme activity was recorded (116 U/ml) in the culture filtrate of POFU2. More than two fold increase in laccase activity was recorded in two fusants- POFU2 and POFU3 as compared to the parent strains. In laccase isozyme analysis, fusants showed bands common to either of the parental strains or to both. Further non- parental new bands were observed in the laccase isozyme patterns of POFU2 and this fact indicates that the isolates were fusants between POM1 and POM2.
---------------------------------------------------------------------------------------------------------

Author Affiliations

Ch. Vijaya1, M.A. Singaracharya2, M. Vijaya Lakshmi3, R. Mallikarjuna Reddy4

Corresponding Author: vijayalch@gmail.com

---------------------------------------------------------------------------------------------------------