Lactic acid fermentation by cells immobilised on various porous cellulosic materials and their alginate/poly-lactic acid composites

Porous delignified cellulose (or tubular cellulose, abbr. TC) from Indian Mango (Mangifera indica) and Sal (Shorea robusta) wood and Rice husk, and TC/Ca-alginate/polylactic acid composites, were used as Lactobacillus bulgaricus immobilisation carriers leading to improvements in lactic acid fermentation of cheese whey and synthetic lactose media, compared to free cells. Specifically, shorter fermentation rates, higher lactic acid yields (g/g sugar utilised) and productivities (g/L d), and higher amounts of volatile by-products were achieved, while no significant differences were observed on the performance of the different immobilised biocatalysts. The proposed biocatalysts are of food grade purity, cheap and easy to prepare, and they are attractive for bioprocess development based on immobilised cells. Such composite biocatalysts may be used for the co-immobilisation of different microorganisms or enzymes (in separate layers of the biocatalyst), to efficiently conduct different types of fermentations in the same bioreactor, avoiding inhibition problems of chemical or biological (competition) nature.