Enhanced phytase production through interspecific protoplast fusion of Aspergillus niger CFR 335 and Aspergillus ficuum SGA 01 auxotrophic mutants

Interspecific protoplast fusion between Aspergillus niger CFR 335 and Aspergillus ficuum SGA 01 auxotrophic mutant strains was carried out in the presence of PEG-3500 in order to enhance the phytase production. The protoplasting frequency found was 2.64 × 10−3 and 3.72 × 10−3 while the regeneration frequency was 32 × 10−2 and 47 × 10−2 in A. niger CFR 335 and A. ficuum SGA 01 respectively. Fusion frequency of 90 × 10−2 was obtained when equal numbers of two protoplasts were induced to fuse. Sixteen stable hybrids were characterized for phytase production, their biomass and DNA contents. The hybrid biomasses were subjected to proximate analysis such as estimation of total sugars, proteins, total lipids and ash. H1 was found promising with high stability and delayed sporulation with the onset after 10 days of incubation while the maximum enzyme production of 126.2 U/gds was attained by 6–7 days, in solid-state fermentation medium. As there are no such studies reported till date, the present work opens a new area in phytase research in developing stable hybrids with desirable characteristics to meet present market demand for the enzyme.