โ Scribed by Detlef Siegmund; Hans Diekmann
No coin nor oath required. For personal study only.
An indirect method for biomass determination was developed for aerobic cultivation in media containing solid substrates. This method involved off-line estimation of oxygen uptake with an oxygen electrode using a calibration factor and was applied to penicillin fermentation with Penicillium chrysogenum. The volumetric oxygen uptake rate was independent of the amount of sample sealed in the measuring cell. Storage of the sample for a period up to 2.5 h also had no influence on the rate of 02 uptake. The specific 02 uptake rate at 70 to 75 h fermentation time was used as the "calibration factor" to calculate the respiration-active part of the biomass. Specific penicillin V formation rates related to net dry weight, respiration-active biomass (XA) and RNA content were compared. Only the penicillin V production rate related to XA showed a similar behaviour as the penicillin V production rate related to R N A content. For this reason, it is assumed that XA, like R N A content, is more closely related to the metabolic state of the cells than the net dry weight. This method, therefore, provides a more suitable reference parameter for fermentation control than the generally used net dry weight.
๐ SIMILAR VOLUMES