Resumo

Ribonucleotides have been successfully used in pharmaceutical industry as an immunological modulator and in food industry as a flavour enhances. They could also be associated with anti-tumour, anti-viral and probiotic effects. These applications justify the interest on their production, preferably using a low-cost process. The objective of this study was to produce ribonucleotides by Kluyveromyces marxianus ATCC 8554 using whey, a dairy industry waste, as the main substrate under bath fermentation conditions. Whey has high biochemical oxygen demand, causing serious environmental problems for dairy industries. A fractioned factorial 2^5-1 with three repetitions at central point was designed. The effect of temperature, pH, aeration rate, agitation and initial cellular concentration were simultaneously studied. Samples were collected at baseline and at every two hour period until 12 hours. The evaluated variables were ribonucleotides and biomass production and lactose consumption. The highest ribonucleotides production (28.7 mg.g^-1 of dry biomass) was observed at 30^oC, pH 5.0 and 1 g.L^-1 initial cellular concentration after 2 hours of fermentation. Agitation and aeration rate did not influence on ribonucleotides production. Maximum lactose consumption (98.7 %) and biomass production (6.0 g.L^-1 were observed after 12 hours of fermentation. Whey utilization for the production of ribonucleotides by fermentative process is an ideal strategy to overcome its pollutant effect by reducing biochemical oxygen demand after the incubation. Looking at the today's environmental concerns, production of value-added products such as ribonucleotides from whey can be a cost effective, appropriate and safe-environment method. Whey seems to be a suitable medium for ribonucleotides production by Kluyveromyces marxianus under the optimized conditions at industrial scale.