Lactic acid is a significant chemical for food, cosmetic, pharmaceutical and chemical industry. Currently, Serbia imports lactic acid and utilization of distillery stillage, a waste water from bioethanol production, as a cheap substrate for lactic acid fermentation could be an efficient and environmentally friendly approach. The main goal of this work was to investigate the possibilities of integrated production of lactic acid and animal feed on an industrial distillery stillage from bioethanol production on starch feedstock. Chemical analysis of the stillage has shown high content of proteins and valuable composition of minerals for the growth of LAB. In the selection process, Lactobacillus rhamnosus ATCC 7469 was chosen as the most promising strain for integrated production of lactic acid and biomass suitable for animal feed. The kinetics of lactic acid and biomass production in the batch fermentation and the impact of temperature, inoculum concentration, shaking and pH control were evaluated. The temperature of 41°C, shaking (90 rpm) and inoculum concentration of 5% (v/v) were selected for the fermentation. Among two different neutralizing agents (powdered CaCO3 and 30% solution of NaOH) a solution of 30% NaOH was selected for pH adjustment in four hour intervals during the fermentation. This system enabled the most optimal pH control and resulted in high lactic acid productivity and extensive growth of Lb. rhamnosus ATCC 7469. Significant improvements of the process were achieved in fed-batch fermentation where the final concentration of lactic acid was increased for 47.6 % and volumetric productivity for 21 % over the batch process. Maximal lactic acid productivity in fed-batch fermentation was 1.80 g L-1 h-1, with lactic acid yield of 0.87 g g-1 and lactic acid concentration of 97.1 g L-1. The number of viable cells at the end of fermentation was 109 CFU ml-1. The fermentation with a recirculation of immobilized Lb. rhamnosus ATCC 7469 onto zeolite was studied as a fermentation strategy. The strong adsorption of Lb. rhamnosus ATCC 7469 cells onto the zeolite surface allowed easy cell separation from the fermentation media, dense growth and high stability of immobilized cells for reuse in repeated batch cycles. A number of viable cells of over 1010 CFU per g of zeolite was achieved at the end of fourth fermentation cycle. A maximal process productivity of 1.69 g L-1, maximal lactic acid concentration of 42.19 g L-1 and average yield coefficient of 0.96 g g-1 were reached in the fermentation of stillage without mineral or nitrogen supplementation. However, in accordance to mineral requirements of Lb. rhamnosus ATCC 7469 and chemical content of minerals in stillage, exchange of Na+ ions in zeolite structure with selected Mg was performed. Exchange of Na+ with Mg2+ ions had improved immobilization of bacterial cells and increased lactic acid production for approximately 10%. Suitability of the fermentation residuals after lactic acid separation for animal nutrition was assessed after determination of chemical composition and calculation of energy parameters. The digestibility of the stillage remained after lactic acid production was 96.63 % DM with the high protein content of 38.65 % DM and values of digestible and methabolisable energy above 4000 kcal kg-1 DM. The in vitro survival test has shown survival of 88% of bacteria after 4h incubation under pH=2.5 and 85.7% after 4h incubation in the presence of 0.3% of bile. These values are high so it could be expected for Lb. rhamnosus ATCC 7469 to survive passage through stomach and exhibit beneficial effect on animal health. The strain has shown antimicrobial effect and capability to produce exopolysaccharides. These findings qualify residuals from lactic acid fermentation on stillage as a highquality feed predominantly for monogastric animals. The results have shown that the stillage from bioethanol production could be used as an inexpensive substrate for integral production of lactic acid and monogastric animal feed with probiotics. Mlečna kiselina je važna supstanca za prehrambenu, farmaceutsku i hemijsku industriju. Srbija trenutno uvozi mlečnu kiselinu pa bi korišćenje destilerijske džibre, otpadne vode iz procesa proizvodnje bioetanola, kao jeftinog supstrata u proizvodnji mlečne kiseline moglo biti efikasna i ekološki povoljna strategija. Osnovni cilj ove disertacije je bio da se ispita mogućnost integrisane proizvodnje mlečne kiseline i stočne hrane na industrijskoj destilerijskoj džibri iz proizvodnje bioetanola na skrobnim sirovinama. Hemijskom karakterizacijom džibre je pokazano da je džibra bogata proteinima i da sadrži odgovarajući sastav jona metala za rast bakterija mlečne kiseline. U toku selekcije mikroorganizama odabran je soj Lactobacillus rhamnosus ATCC 7469, kao odgovarajući soj za paralelnu proizvodnju mlečne kiseline i biomase pogodne za stočnu ishranu. U šaržnom sistemu je ispitan uticaj temperature, koncentracije inokuluma, mešanja i kontrole pH. Nakon optimizacije, odabrana je temperature od 41°C, mešanje od 90 obrt/min, koncentracija inokuluma 5 % (v/v). Ispitana je mogućnost korišćenja CaCO3 i 30% NaOH kao sredstava za neutralizaciju i kontrolu pH vrednosti i odabran je dodatak 30% NaOH u četvorosatnim intervalima kao najpovoljniji za integrisani postupak proizvodnje mlečne kiseline i stočne hrane. Primenom NaOH je ostvarena visoka produktivnost i intenzivan rast Lb. rhamnosus ATCC 7469. Značajno unapređenje procesa je postignuto primenom dolivnog postupka gde je konačna koncentracija mlečne kiseline u medijumu povećana za 47,6% a zapreminska produktivnost za 21% u odnosu na šaržni postupak. Maksimalna postignuta produktivnost mlečne kiseline je iznosila 1,80 g L-1 h-1, sa prinosom mlečne kiseline od 0,87 g g-1 i koncentracijom mlečne kiseline od 97,1 g L-1. Broj vijabilnih ćelija po završetku fermentacije je bio 109 CFU ml-1. Recirkulacioni šaržni postupak sa imobilisanim Lb. rhamnosus ATCC 7469 na zeolitu je takođe isptivan. Snažna adsorpcija ćelija na površinu zeolita je omogućila lako odvajanje imobilizata od fermentisanog medijuma, gust rast ćelija u biofilmu i visoku stabilnost imobilisanih ćelija za recirkulaciju. Na kraju četvrtog ciklusa broj vijabilnih imobilisanih ćelija iznosio je više od 1010 CFU g-1 zeolitnog nosača. U šaržnom procesu sa recirkulacijom na tečnoj džibri bez dodatka izvora azota i minerla najviša postignuta produktivnost je iznosila 1,69 g L-1 h-1, uz maksimalnu koncentraciju mlečne kiseline 42,19 g L-1 i prosečni koeficijent prinosa od 0,96 g g-1. Ipak, u skladu sa potrebama Lb. rhamnosus ATCC 7469 i mineralnim sastavom džibre izvršena je i modifikacija zeolita, izmenom jona Na+ jonima Mg2+, što je rezultovalo povećanom adsorpcijom bakterija na površinu modifikovanog zeolita, kao i povećanjem proizvodnje mlečne kiseline za oko 10%. Ostaci nakon mlečno-kiselinske fermentacije i odvajanja tečne frakcije sa mlečnom kiselinom su analizirani sa aspekta primene u ishrani životinja nakon hemijske analize i izračunavanja važnih energetskih parametara. Svarljivost ostataka nakon fermentacije je bila 96,63 % SM, sa više od 38,65% SM proteina, uz veoma visoke vrednosti svarljive i metaboličke energije od preko 4000 kcal kg-1 SM. Pokazano je da u in vitro uslovima 88% ćelija Lb. rhamnosus ATCC 7469 preživljava četvorosatnu izloženost pH=2,5 i 85,7% ćelija preživljava četvorosatnu izloženost žučnim solima u koncentraciji 0,3%, uz ispoljenu antimikrobnu aktivnost i sposobnost proizvodnje egzopolisaharida. Zbog visokog preživljavanja Lb. rhamnosus ATCC 7469, može se očekivati da soj preživi prolazak kroz gastrointestinalni trakt i pozitivno deluje na zdravlje životinja. Na osnovu svojih karateristika ostaci džibre nakon mlečno-kiselinske fermentacije predstavljaju kvalitetnu hranu prvenstveno za monogastrične životinje. Zaključuje se da se destilerijska džibra može koristiti bez azotnih i mineralnih dodataka kao jeftin supstrat za proizvodnju mlečne kiseline sa visokom produktivnošću (1,80 g L-1 h-1) uz paralelnu proizvodnju kvalitetne stočne hrane za monogastrične životinje obogaćene probiotskim bakterijama.