Abstract:
The exploitation of various agro-industrial wastes for microbial cellmass production
of Kluyveromyces marxianus, kefir, and Saccharomyces cerevisiae is reported in the present
investigation. Specifically, the promotional effect of whole orange pulp on cell growth in
mixtures consisting of cheese whey, molasses, and potato pulp in submerged fermentation
processes was examined. A 2- to 3-fold increase of cell mass was observed in the presence of
orange pulp. Likewise, the promotional effect of brewer’s spent grains on cell growth in solid
state fermentation of mixtures of whey, molasses, potato pulp, malt spent rootlets, and orange
pulp was examined. The cell mass was increased by 3-fold for K. marxianus and 2-fold for S.
cerevisiae in the presence of these substrates, proving their suitability for single-cell protein
production without the need for extra nutrients. Cell growth kinetics were also studied by
measurements of cell counts at various time intervals at different concentrations of added
orange pulp. The protein content of the fermented substrates was increased substantially,
indicating potential use of mixed agro-industrial wastes of negligible cost, as protein-enriched
livestock feed, achieving at the same time creation of added value and waste minimization.
