ISSN:
1574-6968
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Marinobacter sp. strain CAB was cultivated with or without porous glass beads as solid support. Two substrates were used: the hydrophilic sodium lactate and a hydrophobic C18-isoprenoid ketone (6,10,14-trimethylpentadecan-2-one (TMP)). The substrate adsorption onto the beads was measured. Bacterial adhesion was determined by a direct count technique and amounted to 70% of total cells. In the immobilised cell cultures (ICC), generation times were 1.5 and 1.8 times shorter than in the planktonic cultures (FCC) with sodium lactate and with TMP, respectively. In ICC, the growth yields were lower (15.3FCC×109 and 0.8ICC×109 bacteria mg−1 of sodium lactate; 50FCC×109 and 35ICC×109 bacteria mg−1 of TMP). The mineralisation of substrates was estimated after mass spectrometric determination of the CO2 production rates of both free and immobilised cell cultures. The results indicated a higher specific CO2 production rate in the ICC with sodium lactate (3.1FCC±0.2 and 3.5ICC±0.3 nmol CO2 mg−1 protein min−1) but not in the ICC with TMP (1.9FCC±0.7 and 0.5ICC±0.3 nmol CO2 mg−1 protein min−1). The affinities for the two substrates were lower in the presence of the solid support (Km,ICC=18.2±0.2 μM and 37.1±2.0 μM, for sodium lactate and TMP, respectively) than without support (Km,FCC=8.5±1.5 μM and 8.4±1.2 μM, for sodium lactate and TMP, respectively). Moreover, the presence of a solid support showed a lower inhibition by the TMP (Ki,FCC=3.8±1.0 μM and Ki,ICC=12.2±2.5 μM) which may explain why the immobilised cell cultures degraded hydrophobic TMP more efficiently than the planktonic cultures.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1574-6968.2001.tb09455.x
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