Production of 2, 3-butanediol from rennet whey permeate by Klebsiella pneumoniae immobilized in alginate gel : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Biotechnology at Massey University
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The successful immobilization of cells of Klebsiella pneumoniae(NCIB 8017) in sodium alginate gels was demonstrated. A cell to alginate ratio of 1ml original cell culture to 1.25ml sodium alginate solution(20g/l) was found to be optimum for butanediol production from rennet whey permeate. Preliminary batch fermentation studies revealed that immobilized cells incubated in a non-agitated mode produced a higher concentration of 2,3-butanediol than those in an agitated mode. Smaller beads(1.8mm diameter) produced higher quantities of 2,3-butanediol than larger beads(5.5mm diameter), while bead storage at 4°C in either 0.1M Tris-HC1 buffer or the gelating agent proved satisfactory although some activation was required to realise the full butanediol producing potential of the beads. Supplementation of 3g/l calcium chloride to the whey permeate was non-inhibitory to butanediol production and led to enhanced calcium alginate bead stability. Acclimatization of cells in high lactose concentration prior to cell immobilization did not result in enhanced butanediol production or lactose utilization. Product and substrate inhibition effects were not detected. In batch fermentation, a butanediol productivity of 0.11g/l.h was obtained. In continuous fermentation in a CSTR, the productivity was increased to 0.74g/l.h. Using packed columns operated in the vertical mode, similar productivities to those using the CSTR was attained. However, the columns suffered from an accumulation of carbon dioxide bubbles. This problem was overcome by placing a stainless steel mesh inside the column, and operating at an angle of 10° to the horizontal. Under these conditions, a butanediol productivity of 2.40g/l.h was achieved, representing an improvement over values reported in the literature.
Whey products, Rennet, Butanediol