Measurement Of Fungal Viable Biomass And Effect Of Pressure On Cell Viability

A biochemical method, using Absidia coerulea as model strain, has been developed for measuring fungal viable biomass in this paper firstly. In addition, the effect of mild pressure on cell viability, cellular membrane permeability, cell morphology and metabolism of Absidia coerulea and Baker yeast CICC1339 CICC1447 was investigated.1. Establishment of biochemical method for measurement of fungal biomass The procedure of DHA measurement was established using Absidia coeruleaas model strain, as described following: 0.1g fresh fungal was placed in centrifugal tube, added 3mL 0.5% TTC-PBS (pH8.0) solution. This mixture was incubated at 45 ℃ for 60 min. the reaction was stopped by adding 0.5ml formaldehyde. After centrifugation the supernatant was discarded. The fungal, after washed by sterilized water, was gathered to colorimetric tube. 25ml 80% acetone was used to extract red TF from fugal at room temperature for 2h. The absorbance of the extracted solution was read at 485nm and the DHA was then obtain by calculation, the validity of assay is proved by correlation established between OD485 and the wet weight of viable mycelium(r~2=0.98). Moreover, applying this procedure the specific DHA can be used for assessing the viability of fungi accurately.2. Effect of mild pressure on activity and HC conversion viability of Absidia coeruleaThe Absidia coerulea pellet could keep activity (>80%) and cellular DHA maintain high lever, after 0.5MPa pressure treatment using air as pressure-media. The results indicated that mild pressure could improve cell membrane permeabilization. In addition, Electron microscopic images showed that the cell morphology was changed. It also is confirmed that the production of hydrocortisone could increased 22.4 % . by the novel grading-pressure biotransformation technology procedure, compared with atmosphere control sample.3. Effect of mild pressure on activity and metabolism of yeastUsing air as pressure-media, baker yeast CICC1339 and CICC1447 were cultivated under 0.5MPa. The growth curve shows the pressure inhibited the biomass synthesis of baker yeast. It was demonstrated that pressure changed the cell morphology by ESEM images. With increasing of pressure value and prolonging of holding time, the conductance, A280 and A260 of yeast suspending increased accordingly, and all higher than control samples. The results indicated...