ISSN:
1573-0972
Keywords:
Alginate
;
freeze-substitution
;
immobilization
;
Zymomonas mobilis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Abstract Alginate-immobilized Zymomonas mobilis cells produced 17.8% (v/v) ethanol in less than 24 h, with an ethanol yield of 97%, compared with 88% for free cells, using a fed-batch cultivation technique. The substrate, glucose, was added intermittently in powder form to foster nucleation of the CO2 formed. Repeated-batch cultivation led to complete utilization of approximately 200 g glucose/l in 7.5 h with a 98% conversion efficiency to ethanol. Free cells used the glucose less efficiently (conversion efficiency of 78%), and even after 100 h the glucose was not fully consumed. Freeze-substitution electron microscopy studies showed that immobilized cells generally displayed lesser blebbing and membrane disruption than free cells. These studies further suggest that membrane blebbing may be due to an effect of high initial glucose levels, and not due to the accumulation of end-products ethanol and CO2.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00383082
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