Production of hybrid strains among Pleutorus and Lentinula and evaluation of their mycelial growth kinetics on malt extract agar and wheat grain using the Gompertz and Hill models
Three inter-generic hybrid strains were obtained by pairing compatible neohaplonts recovered by dedikaryotization of four parental strains, i.e. Pleurotus ostreatus (CC060), Pleurotus djamor (CC051) and Lentinula edodes (CC003 and CC004). Fifteen neohaplonts were recovered employing homogenization time periods for Pleurotus spp. since 60 to 90 s, and for Lentinula edodes strains time periods ranged from 5 to 20 s, and incubation at 28 °C in a peptone-glucose solution (PGS). The mycelial growth of the parental and hybrid strains was determined on malt extract agar (MEA) and wheat grain by calculating the parameters A, B and C of nonlinear regression models. For the parameter A, the mycelial growth on MEA showed values ranged from 1.08 to 1.28, and for the parameter B since 5.65 to 20.85. On the other hand, the A values by mycelium growth on wheat grain ranged from 1.57 to 16.13, for B since 28.36 to 86.53 and for C were in an interval from 11.89 to 44.24. Parental and hybrid strains presented instantaneous velocity values on MEA since 2.88 to 7.26 cm2•day-1, whereas on wheat grain were in an interval from 5.45 to 10.05 cm3•day-1. Furthemore, the µmax values on MEA and wheat grain were calculated by using the Gompertz model and the λ values on both medium were estimated by using the Hill model, the µmax values on MEA ranged from 0.26 to 1.69 day-1 and λ values in an interval from 0.41 to 2.74, whereas the µmax values on wheat grain ranged from 0.05 to 0.43 day-1 and λ since 1.82 to 28 h. Moreover, the estimated equations based on nonlinear models were used to calculate the µmax values on MEA and wheat grain of the strains and the λ values were obtained by using the µmax values of the proposed equations on the Hill model, the µmax values on MEA ranged from 0.44 to 1.27 day-1 and the λ values between 0.57 to 1.72 h, while the µmax values on wheat grain ranged from 0.04 to 0.64 day-1 and λ values in an interval from 1.26 to 20.11 h. The results evidenced that the hybrid strains of PleurotusxLentinula presented highest rate of growth in comparison with the parental, encouraging the production of hybrid strain and their use in the industrial field.