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The aim of this study was the selection of appropriate supplements for the probiotic whey-based beverage production by Lactobacillus johnsonii NRRL B-2178. The analysis of the main effects and their interactions was performed by using a fractional factorial experimental design through a small number of experiments. After 8h of fermentation of the reconstituted whey, enriched by investigated supplements, a cell number achieved in the probiotic whey-based beverage was determined. By using a statistical analysis, the amount of supplements which are necessary to obtain the maximal number of viable cells in the beverage was also determined. Based on the obtained results, among all nitrogen sources the yeast extract in the concentration of 1,5 % achieves the most significant influence on the Lactobacillus johnsonii NRRL B-2178 growth. As the sources of vitamins and minerals, piridoxal and ZnSO4 has the most significant influence on the number of cells at concentrations of 0,001 % and 0,3 %, respectively. By examining the three groups supplements, the largest number of cells approximately 8,80 log(CFU/mL) can be obtained by using the maximum amount of the yeast extract.

The aim of this study was the selection of appropriate supplements for the probiotic whey-based beverage production by Lactobacillus johnsonii NRRL B-2178. The analysis of the main effects and their interactions was performed by using a fractional factorial experimental design through a small number of experiments. After 8h of fermentation of the reconstituted whey, enriched by investigated supplements, a cell number achieved in the probiotic whey-based beverage was determined. By using a statistical analysis, the amount of supplements which are necessary to obtain the maximal number of viable cells in the beverage was also determined. Based on the obtained results, among all nitrogen sources the yeast extract in the concentration of 1,5 % achieves the most significant influence on the Lactobacillus johnsonii NRRL B-2178 growth. As the sources of vitamins and minerals, piridoxal and ZnSO4 has the most significant influence on the number of cells at concentrations of 0,001 % and 0,3 %, respectively. By examining the three groups supplements, the largest number of cells approximately 8,80 log(CFU/mL) can be obtained by using the maximum amount of the yeast extract. U ovom radu ispitan je uticaj različitih izvora azota, vitamina i minerala na rast soja Lactobacillus johnsonii NRRL B-2178 u cilju postizanja maksimalnog broja živih ćelija pri proizvodnji probiotskog napitka na bazi surutke. Analiza uticaja pojedinačnih i združenih efekata ispitivanih dodataka vršena je primenom frakcionalnog faktorskog dizajna eksperimenata uz izvođenje minimalnog broja eksperimenata. Nakon 8 h fermentacije surutke obogaćene ispitivanim dodacima određivan je broj živih ćelija (kao odgovor sistema) u probiotskom napitku. Statističkom obradom podataka ujedno je procenjena i količina dodataka koja je neophodna za postizanje maksimalnog broja živih ćelija u napitku. Na osnovu dobijenih rezultata, iz grupe ispitanih izvora azota najveći uticaj na rast soja Lactobacillus johnsonii NRRL B-2178 ostvaruje ekstrakt kvasca pri koncentraciji od 1,5 % (w/v). Kao izvori vitamina i minerala najveći uticaj na rast ćelija ispoljavaju vitamin B6 i ZnSO4 u koncentracijama 0,001 % i 0,3 %, respektivno. Pri ispitivanju sve tri grupe dodataka najveći broj ćelija (oko 8,80 log CFU/mL) se može ostvariti primenom maksimalne količine ekstrakta kvasca.

The production of lactic acid on a liquid distillery stillage remaining after the bioethanol production on a mixture of waste bread and waste water from the production of wheat gluten was studied in this work. The lactic acid fermentation was performed with a probiotic lactic acid bacteria Lactobacillus rhamnosus ATCC 7469. During the fermentation, parameters such as the concentration of lactic acid (according to Taylor method), the concentration of reducing sugars (spectrophotometric method according to Miller), pH, and the bacterial growth (counting method on agar plates) were followed. The optimal conditions for the production of lactic acid such as: temperature, inoculum concentration, concentration of added CaCO3 for neutralization and shaking intensity were determined. Under these conditions, a yield of over 80% of the theoretical yield was achieved. The highest intensity of the lactic acid production was noticed during the first 24 hours of fermentation, while the fermentation completely ended after 72 hours. An intensive growth of the L. rhamnosus ATCC 7469 was detected under the optimal conditions, indicating a possibility of the parallel production of lactic acid and probiotic biomass. This approach could be economically more favorable. The liquid stillage used in this study was shown as a good substrate for lactic acid fermentation. U radu je ispitivana proizvodnja mlečne kiseline na tečnoj destilerijskoj džibri nastaloj nakon proizvodnje bioetanola iz smeše otpadnog hleba i otpadne vode iz proizvodnje glutena. Mlečno-kiselinska fermentacija je vršena pomoću probiotički aktivne bakterije Lactobacillus rhamnosus ATCC 7469. U toku fermentacije praćen je sadržaj mlečne kiseline (po metodi Taylor-a), sadržaj redukujućih šećera (spektrofotometrijski metodom po Miller-u), pH, kao i rast bakterije (brojanjem ćelija Koh-ovom metodom na agarnim pločama). Utvrđeni su optimalni uslovi za proizvodnju mlečne kiseline: temperatura, koncentracija inokuluma, koncentracija dodatog CaCO3 kao sredstva za neutralizaciju i intenzitet mešanja. Pri utvrđenim optimalnim uslovima ostvareni su prinosi od preko 80% od teorijskog prinosa mlečne kiseline u mikroaerofilnoj fermentaciji sa mešanjem. Najveći intezitet fermentacije ostvaren je u toku prvih 24 časa, a fermentacija je završena nakon 72 časa. Pri optimalnim uslovima mlečnokiselinske fermentacije uočen je intenzivan rast bakterije Lactobacillus rhamnosus ATCC 7469 što ukazuje na mogućnost paralelne proizvodnje mlečne kiseline i probiotičke biomase, čime bi se mogli postići bolji ekonomski efekti. Ispitivana džibra se pokazala kao pogodan medijum za mlečno kiselinsku fermentaciju.

Mlečna kiselina nalazi široku primenu u prehrambenoj, kozmetičkoj, farmaceutskoj i hemijskoj industriji. Poslednjih godina najvažnija primena mlečne kiseline je u proizvodnji polimera mlečne kiseline koji predstavljaju najčešće korišćene biorazgradive i biokompatibilne plastične materijale. Mlečna kiselina se dominantno proizvodi fermentacionim putem pomoću bakterija mlečne kiseline. Visoki prinosi D- ili L-mlečne kiseline u fermentaciji jeftinih izvora ugljenika su ključne odlike održivog fermentacionog postupka. Predmet istraživanja u okviru ove doktorske disertacije bio je da se ispita mogućnost proizvodnje mlečne kiseline na kombinovanom supstratu na bazi otpadne krompirove džibre iz proizvodnje bioetanola i melase šećerne repe kao sporednog proizvoda industrije šećera. Osnovni cilj je definisanje tehnološkog postupka koji će primenom jeftinih sirovina omogućiti efikasnu i ekonomski održivu proizvodnju mlečne kiseline i valorizaciju sporednih proizvoda fermentacije u ishrani preživara. Hemijskom analizom je pokazano da kombinovani supstrat na bazi krompirove džibre i melase šećerne repe predstavlja dobar izvor azota, fermentabilnih šećera i mineralnih materija neophodnih za rast bakterija mlečne kiseline i proizvodnju mlečne kiseline. Selekcijom soja koji efikasno fermentiše šećere prisutne u kombinovanom otpadnom supstratu, za proizvodnju mlečne kiseline je odabran soj Lactobacillus paracasei NRRL B-4564. U cilju poboljšanja efikasnosti proizvodnje mlečne kiseline, L. paracasei je uspešno adaptiran na potencijalno inhibitorna jedinjenja prisutna u melasi šećerne repe. U dolivnoj fermentaciji pomoću adaptiranog L. paracasei A-22 koncentracija mlečne kiseline (169,9 g/L) je bila za 51% veća u odnosu na koncentraciju mlečne kiseline koja je ostvarena pomoću neadaptiranog soja (107,1 g/L). Imobilizacija L. paracasei na repin rezanac, pivski trop i ljusku suncokreta je omogućila efikasna proizvodnju mlečne kiseline u ponovljenoj šaržnoj fermentaciji i istovremenu valorizaciju zaostalih fermentisanih nosača kao hraniva za životinje... Lactic acid has been widely used in food, cosmetics, pharmaceutical and chemical industry. In recent years, the most important application of lactic acid is in production of poly-lactic acid (PLA) polymers, which are most frequently applied biocompatible and biodegradable plastic materials. Dominant route for lactic acid production is fermentation by lactic acid bacteria. High yields of D- or L-lactic acid in fermentation on low-cost carbon and nitrogen sources are key factors for sustainable lactic acid production. The aim of this research was to evaluate the possibility of lactic acid production on a combined substrate based on potato stillage from bioethanol production and sugar beet molasses from sugar industry. The main goal was to develop a process based on utilization of low-cost feedstocks that will enable efficient and sustainable lactic acid production and valorization of by-products remained after lactic acid fermentation in animal nutrition. Chemical composition of the stillage and molasses indicate that the combination of these substrates can provide necessary nutrients and fermentable sugars for the growth of lactic acid bacteria and efficient lactic acid production. Among three assayed strains, Lactobacillus paracasei NRRL B-4564 gave the highest lactic acid production and growth on cheap and complex waste substrate. In order to enhance lactic acid production, L. paracasei was successfully adapted to inhibitory compounds contained in sugar beet molasses. Fed-batch fermentation by adapted L. paracasei A-22 resulted in 51 % higher lactic acid concentration (169.9 g/L) compared to fermentation with parent strain (107.1 g/L). Immobilization of L. paracasei onto sugar beet pulp, brewers’ spent grain and sunflower seed hull enabled efficient lactic acid production in five successive batches and valorization of fermented support materials in ruminant nutrition...

Lactic acid has been widely used in food, cosmetics, pharmaceutical and chemical industry. In recent years, the most important application of lactic acid is in production of poly-lactic acid (PLA) polymers, which are most frequently applied biocompatible and biodegradable plastic materials. Dominant route for lactic acid production is fermentation by lactic acid bacteria. High yields of D- or L-lactic acid in fermentation on low-cost carbon and nitrogen sources are key factors for sustainable lactic acid production. The aim of this research was to evaluate the possibility of lactic acid production on a combined substrate based on potato stillage from bioethanol production and sugar beet molasses from sugar industry. The main goal was to develop a process based on utilization of low-cost feedstocks that will enable efficient and sustainable lactic acid production and valorization of by-products remained after lactic acid fermentation in animal nutrition. Chemical composition of the stillage and molasses indicate that the combination of these substrates can provide necessary nutrients and fermentable sugars for the growth of lactic acid bacteria and efficient lactic acid production. Among three assayed strains, Lactobacillus paracasei NRRL B-4564 gave the highest lactic acid production and growth on cheap and complex waste substrate. In order to enhance lactic acid production, L. paracasei was successfully adapted to inhibitory compounds contained in sugar beet molasses. Fed-batch fermentation by adapted L. paracasei A-22 resulted in 51 % higher lactic acid concentration (169.9 g/L) compared to fermentation with parent strain (107.1 g/L). Immobilization of L. paracasei onto sugar beet pulp, brewers’ spent grain and sunflower seed hull enabled efficient lactic acid production in five successive batches and valorization of fermented support materials in ruminant nutrition... Mlečna kiselina nalazi široku primenu u prehrambenoj, kozmetičkoj, farmaceutskoj i hemijskoj industriji. Poslednjih godina najvažnija primena mlečne kiseline je u proizvodnji polimera mlečne kiseline koji predstavljaju najčešće korišćene biorazgradive i biokompatibilne plastične materijale. Mlečna kiselina se dominantno proizvodi fermentacionim putem pomoću bakterija mlečne kiseline. Visoki prinosi D- ili L-mlečne kiseline u fermentaciji jeftinih izvora ugljenika su ključne odlike održivog fermentacionog postupka. Predmet istraživanja u okviru ove doktorske disertacije bio je da se ispita mogućnost proizvodnje mlečne kiseline na kombinovanom supstratu na bazi otpadne krompirove džibre iz proizvodnje bioetanola i melase šećerne repe kao sporednog proizvoda industrije šećera. Osnovni cilj je definisanje tehnološkog postupka koji će primenom jeftinih sirovina omogućiti efikasnu i ekonomski održivu proizvodnju mlečne kiseline i valorizaciju sporednih proizvoda fermentacije u ishrani preživara. Hemijskom analizom je pokazano da kombinovani supstrat na bazi krompirove džibre i melase šećerne repe predstavlja dobar izvor azota, fermentabilnih šećera i mineralnih materija neophodnih za rast bakterija mlečne kiseline i proizvodnju mlečne kiseline. Selekcijom soja koji efikasno fermentiše šećere prisutne u kombinovanom otpadnom supstratu, za proizvodnju mlečne kiseline je odabran soj Lactobacillus paracasei NRRL B-4564. U cilju poboljšanja efikasnosti proizvodnje mlečne kiseline, L. paracasei je uspešno adaptiran na potencijalno inhibitorna jedinjenja prisutna u melasi šećerne repe. U dolivnoj fermentaciji pomoću adaptiranog L. paracasei A-22 koncentracija mlečne kiseline (169,9 g/L) je bila za 51% veća u odnosu na koncentraciju mlečne kiseline koja je ostvarena pomoću neadaptiranog soja (107,1 g/L). Imobilizacija L. paracasei na repin rezanac, pivski trop i ljusku suncokreta je omogućila efikasna proizvodnju mlečne kiseline u ponovljenoj šaržnoj fermentaciji i istovremenu valorizaciju zaostalih fermentisanih nosača kao hraniva za životinje...

Bioaktivni peptidi predstavljaju granu naučne oblasti koja se veoma brzo razvija. Tokom istraživanja proteina uočeno je da neki proteini nakon digestije ispoljavaju bioaktivnosti koje ne poseduju u svojoj nativnoj formi. To je bio podsticaj za istraživanje uticaja enzimske hidrolize na bioaktivnost proteina. Trenutni naučni stav je da svaki protein može posedovati fragmente koji ispoljavaju neku od mnogih bioaktivnosti. Bioaktivni peptidi dobijeni enzimskom hidrolizom surutke ispoljili su mnoge pozitivne efekte na ljudsko zdravlje... Bioactive peptides are a rapidly developing field of research. During the research it was observed that some peptides which do not show a particular bioactivity become bioactive after ingestion and passing through the gastrointestinal system. That was the stimulus for the development of research on the effect of enzymatic hydrolysis of the bioactive properties of proteins. According to the current state of scientific knowledge, every protein can contain fragments that possess some of many bioactivities. Bioactive peptides, derived by enzymatic hydrolysis of whey protein, have demonstrated characteristics as health-promoting agents...

Bioactive peptides are a rapidly developing field of research. During the research it was observed that some peptides which do not show a particular bioactivity become bioactive after ingestion and passing through the gastrointestinal system. That was the stimulus for the development of research on the effect of enzymatic hydrolysis of the bioactive properties of proteins. According to the current state of scientific knowledge, every protein can contain fragments that possess some of many bioactivities. Bioactive peptides, derived by enzymatic hydrolysis of whey protein, have demonstrated characteristics as health-promoting agents... Bioaktivni peptidi predstavljaju granu naučne oblasti koja se veoma brzo razvija. Tokom istraživanja proteina uočeno je da neki proteini nakon digestije ispoljavaju bioaktivnosti koje ne poseduju u svojoj nativnoj formi. To je bio podsticaj za istraživanje uticaja enzimske hidrolize na bioaktivnost proteina. Trenutni naučni stav je da svaki protein može posedovati fragmente koji ispoljavaju neku od mnogih bioaktivnosti. Bioaktivni peptidi dobijeni enzimskom hidrolizom surutke ispoljili su mnoge pozitivne efekte na ljudsko zdravlje...

Količina proizvoda od surutke na tržištu je zanemarljivo mala u odnosu na količinu fermentisanih mlečnih proizvoda. To navodi na zaključak da bi se unapređenjem procesa fermentacije surutke mogli dobiti novi nekonvencionalni proizvodi koji bi zauzeli značajnije mesto u paleti mlečnih proizvoda namenjenih širokoj potrošnji. U tom smislu, cilj ove doktorske disertacije je bio proizvodnja i karakterisanje funkcionalnih fermentisanih napitaka na bazi surutke. U cilju proizvodnje funkcionalnih fermentisanih napitaka na bazi surutke izvršena je selekcija odgovarajuće kulture mikroorganizama, optimizacija procesa fermentacije i karakterizacija proizvedenog fermentisanog napitka. Tokom selekcije, optimizacije i karakterizacije praćeno je: vreme trajanja fermentacije, sadržaj mlečne kiseline, promena pH, preživljavanje mikroorganizama, sadržaj aminokiselina, sadržaj antioksidanasa, viskozitet, sinerezis kao i nutritivni sastav proizvedenog napitka. Takođe je izvršeno in vitro karakterisanje probiotske aktivnosti odabranih mikroorganizama praćenjem sposobnosti preživljavanja u uslovima simuliranog gastričnog soka, antimikrobne aktivnosti i rezistencije na antibiotike primenom klasičnih mikrobioloških tehnika. U sklopu nutritivne karakterizacije praćena je razgradnje proteina surutke nakon fermentacije. Proizvedeni napitak je nutritivno okarakterisan preračunavanjem nutritivne vrednosti proizvoda, što je predstavljalo polaznu tačku njegovog deklarisanja u skladu sa Pravilnikom o deklarisanju RS, označavanju i reklamiranju hrane 85/2013, ali i EU Regulative 1169/2011. Pored toga, u skladu sa nutritivnim sastavom, napitku su dodeljene nutritivne i/ili zdravstvene izjave odobrene od strane EFSA (European Food Safety Authority), prema EU Regulativi 11924/2011 i Direktivi 432/2012. Proizvod je upakovan u specijalno kreiranu ambalažu, koja je u skladu sa propisima za pakovanje mlečnih proizvoda, čime je dobijeni napitak u potpunosti pripremljen za plasman na tržište. Ispitivanje mogućnosti proizvodnje funkcionalnih fermentisanih napitaka na bazi surutke, primenom različitih sojeva bakterija mlečne kiseline pokazalo je da svi sojevi bakterija mlečne kiseline (ukupno 15) testirani u ovom istraživanju mogu biti primenjeni u procesu... Number of whey based products on the market is negligible compared to the number of fermented dairy products, which suggests that the improvement of the whey fermentation process could result in new unconventional products that take up a significant place in the wide range of dairy products intended for direct consumption. In accordance with that, the aim of this PhD thesis was the production and characterisation of functional fermented whey based beverages. In order to produce the functional fermented whey based beverages, selection of microorganisms, optimisation of the fermentation process and the characterisation of the produced beverages were carried out. During the selection, optimisation and characterisation, fermentation time, titratable acidity, pH value, amino acid content, antioxidative activity, viscosity, syneresis, as well as nutritional composition of produced beverages were followed. In vitro characterisation of probiotic character of the selected microorganisms, by tracking ability to survive under simulated gastric juice, antimicrobial activity and resistance to antibiotics using conventional microbiological techniques were also performed. Within the nutritional characterisation, percentage of whey protein degradation obtained after the fermentation, was examined. Manufactured beverages were nutritionally characterised by recalculating the nutritional value, which was the starting point of its declaration in accordance with the Serbian Regulations on declaration, labelling and advertising of food 85/2013. Also, in accordance with the nutritional composition of the beverages, nutritional and/or health claims approved by EFSA (European Food Safety Authority) and according to EU Regulation 1169/2011 and Regulation 432/2012 were given. The product was packaged in a specially created packaging that complies with the regulations for dairy products, and thus obtained beverage was fully prepared for the market. When examining the possibilities of whey based beverages production using different strains of lactic acid bacteria, it has been shown that all strains of lactic acid bacteria (total of 15) tested in this study can be applied in the production of functional fermented whey based...

Number of whey based products on the market is negligible compared to the number of fermented dairy products, which suggests that the improvement of the whey fermentation process could result in new unconventional products that take up a significant place in the wide range of dairy products intended for direct consumption. In accordance with that, the aim of this PhD thesis was the production and characterisation of functional fermented whey based beverages. In order to produce the functional fermented whey based beverages, selection of microorganisms, optimisation of the fermentation process and the characterisation of the produced beverages were carried out. During the selection, optimisation and characterisation, fermentation time, titratable acidity, pH value, amino acid content, antioxidative activity, viscosity, syneresis, as well as nutritional composition of produced beverages were followed. In vitro characterisation of probiotic character of the selected microorganisms, by tracking ability to survive under simulated gastric juice, antimicrobial activity and resistance to antibiotics using conventional microbiological techniques were also performed. Within the nutritional characterisation, percentage of whey protein degradation obtained after the fermentation, was examined. Manufactured beverages were nutritionally characterised by recalculating the nutritional value, which was the starting point of its declaration in accordance with the Serbian Regulations on declaration, labelling and advertising of food 85/2013. Also, in accordance with the nutritional composition of the beverages, nutritional and/or health claims approved by EFSA (European Food Safety Authority) and according to EU Regulation 1169/2011 and Regulation 432/2012 were given. The product was packaged in a specially created packaging that complies with the regulations for dairy products, and thus obtained beverage was fully prepared for the market. When examining the possibilities of whey based beverages production using different strains of lactic acid bacteria, it has been shown that all strains of lactic acid bacteria (total of 15) tested in this study can be applied in the production of functional fermented whey based... Količina proizvoda od surutke na tržištu je zanemarljivo mala u odnosu na količinu fermentisanih mlečnih proizvoda. To navodi na zaključak da bi se unapređenjem procesa fermentacije surutke mogli dobiti novi nekonvencionalni proizvodi koji bi zauzeli značajnije mesto u paleti mlečnih proizvoda namenjenih širokoj potrošnji. U tom smislu, cilj ove doktorske disertacije je bio proizvodnja i karakterisanje funkcionalnih fermentisanih napitaka na bazi surutke. U cilju proizvodnje funkcionalnih fermentisanih napitaka na bazi surutke izvršena je selekcija odgovarajuće kulture mikroorganizama, optimizacija procesa fermentacije i karakterizacija proizvedenog fermentisanog napitka. Tokom selekcije, optimizacije i karakterizacije praćeno je: vreme trajanja fermentacije, sadržaj mlečne kiseline, promena pH, preživljavanje mikroorganizama, sadržaj aminokiselina, sadržaj antioksidanasa, viskozitet, sinerezis kao i nutritivni sastav proizvedenog napitka. Takođe je izvršeno in vitro karakterisanje probiotske aktivnosti odabranih mikroorganizama praćenjem sposobnosti preživljavanja u uslovima simuliranog gastričnog soka, antimikrobne aktivnosti i rezistencije na antibiotike primenom klasičnih mikrobioloških tehnika. U sklopu nutritivne karakterizacije praćena je razgradnje proteina surutke nakon fermentacije. Proizvedeni napitak je nutritivno okarakterisan preračunavanjem nutritivne vrednosti proizvoda, što je predstavljalo polaznu tačku njegovog deklarisanja u skladu sa Pravilnikom o deklarisanju RS, označavanju i reklamiranju hrane 85/2013, ali i EU Regulative 1169/2011. Pored toga, u skladu sa nutritivnim sastavom, napitku su dodeljene nutritivne i/ili zdravstvene izjave odobrene od strane EFSA (European Food Safety Authority), prema EU Regulativi 11924/2011 i Direktivi 432/2012. Proizvod je upakovan u specijalno kreiranu ambalažu, koja je u skladu sa propisima za pakovanje mlečnih proizvoda, čime je dobijeni napitak u potpunosti pripremljen za plasman na tržište. Ispitivanje mogućnosti proizvodnje funkcionalnih fermentisanih napitaka na bazi surutke, primenom različitih sojeva bakterija mlečne kiseline pokazalo je da svi sojevi bakterija mlečne kiseline (ukupno 15) testirani u ovom istraživanju mogu biti primenjeni u procesu...

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%... 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%...