getpdf

Effects of Water Activity on Kinetics of Simple and Complex Microbial Bioconversions

Krešo Mihaljević, Marijan Bošnjak


PLIVA d.d.,Research Institute, HR-10000 Zagreb, Croatia

Article history:

Received April 21, 1997
Accepted June 13, 1997

Key words:

water activity, D-sorbitol bioconversion, kinetics

Summary:

The effects of water activity on the kinetics of "simple" (biooxidation of D-sorbitol into L-sorbose by means of Gluconobacter suboxydans S-22) and "complex" (biosynthetic conversion of D-sorbitol into Oxytetracycline by means of Streptomyces rimosus R6) microbial processes were studied. Water activity was defined as a function of oxygen solubility. Experiments with shake flask cultures were used to study the kinetics of both processes. Growth of microorganisms, consumption of D-sorbitol and formation of products (L-sorbose and Oxytetracycline) were monitored. Effects of water activity were more expressed in the process of Oxytetracycline biosynthesis than in that of L-sorbose formation. Growth kinetics was affected more than product formation kinetics in both processes. The estimated critical values of water activity were 0.35 (G. suboxydans S-22 growth), 0.40 (S. rimosus R6 growth), 0.21 (L-sorbose formation) and 0.40 (Oxytetracycline biosynthesis) respectively. With decreasing water activity the mass transfer phenomena were observed to become more and more important, especially when considering the liquid-microbial biomass interface as in the case of applying media with D-sorbitol concentration above 500 g/L.


Search FTB


Follow us


 facebook 1 twitter bird_icon

 

QR Code


qrcode

We use cookies to improve our website and your experience when using it. Cookies used for the essential operation of the site have already been set. To find out more about the cookies we use and how to delete them, see our privacy policy.

I accept cookies from this site.

EU Cookie Directive Module Information