Studies on the suitability of alginate-entrapped Chlamydomonas reinhardtii cells for sustaining nitrate consumption processes.
Some aspects of the suitability of alginate beads entrapping Chlamydomonas reinhardtii cells for nitrate consumption from nitrate-containing waters were studied and discussed. Among 14 different metal cations tested as gel bead stabilizing agents, only calcium and barium formed beads showing nitrate-consuming activity. Pure calcium alginate cell entrapment resulted in the most suitable method for active cell immobilization compared to alginate-composite-gel beads based on poly-vinylcaprolactam (PVCL) and poly-vinylpyrrolidone (PVP). To perform a continuous nitrate consumption process, calcium alginate-entrapped cells were first grown in a 2.5 l airlift-loop reactor. A cell loading of about 150 microg Chl. g(-1) gel was achieved. Afterwards, five days nitrate consumption processes were performed and three different dilution rates were applied: (i) D < mu; (ii) D = mu; (iii) D > mu, where mu is the specific growth rate (h(-1)). The maximum consumption rates calculated for each dilution rate were: (i) 3.8, (ii) 6.4 and (iii) 7.2 mg nitrate mg(-1) Chl. h(-1). For low dilution rates (D < mu) some nitrite (< 300 microM) was excreted into the culture medium. However, this concentration of nitrite was not high enough to inhibit nitrate consumption.
Vílchez
C
C
Departamento de Química y CC.MM, Escuela Politécnica Superior, Universidad de Huelva, Spain. cvilchez@uhu.es
Garbayo
I
I
Markvicheva
E
E
Galván
F
F
León
R
R
D000464:Alginates; D000818:Animals; D001673:Biodegradation, Environmental; D019149:Bioreactors; D002412:Cations; D018914:Cells, Immobilized; D016825:Chlamydomonas reinhardtii / Q000254:growth & development / Q000378:metabolism*; D005782:Gels; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D009566:Nitrates / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
D000464:Alginates; D002412:Cations; D005782:Gels; D006603:Hexuronic Acids; D009566:Nitrates; D014874:Water Pollutants, Chemical; D020723:Glucuronic Acid