Cell immobilization in composite agar layer microporous membrane structures: growth kinetics of gel-entrapped cultures and cell leakage limitation by a microporous membrane.
Agar discs containing different amounts of viable Escherichia coli cells (from 10 to 10(6) organisms.g-1 agar) were incubated in a nutrient medium and the growth of agar-entrapped bacteria and free (released) cells was monitored. The study was repeated with composite immobilized-cell structures obtained by placing a microporous membrane filter between the gel matrix and the incubation medium. In both cases, immobilized cells grew exponentially and reached a peak concentration an order of magnitude higher than that of free (suspended) cell cultures. The maximum specific growth rates of entrapped bacteria, ranging between 0.0115 min-1 and 0.0145 min-1, i.e., slightly higher than that of control free cultures (0.011 min-1), showed no clear dependence on the initial cell loading (ICL). The microporous filter proved efficient in limiting cell leakage since it noticeably lengthened the leakage time at a given ICL. This efficiency, however, decreased at high ICL and high growth rate of immobilized organisms.
Jouenne
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Groupe de Technologie Microbienne, URA CNRS no. 500, Université de Rouen, bâtiment INSERM, Bois Guillaume, France.
Bonato
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H
Mignot
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Junter
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GA
D000362:Agar; D002465:Cell Movement; D004926:Escherichia coli / Q000254:growth & development* / Q000502:physiology; D007700:Kinetics; D008567:Membranes, Artificial
D008567:Membranes, Artificial; D000362:Agar