UTVRDJIVANJE UTICAJNIH FAKTORA PROIZVODNJE EGZOPOLISAHARIDA POMOĆU PRIRODNOG IZOLATA LEUCONOSTOC SP. PRIMENOM TEHNIKA STATISTIČKOG DIZAJNA

Abstract

U cilju povećanja prinosa proizvodnje egzopolisaharida (EPS) pomoću prirodnog izolata Leuconostoc sp. izvršeno je ispitivanje uticajnih faktora procesa primenom Plackett-Burman dizajna (Design Expert, 8.0., trial version). Dizajn je obuhvatao jedanaest promenljivih koje se mogu svrstati u dve grupe ispitivanih faktora: sastav podloge (sadržaj saharoze, glukoze, fruktoze, amonijum-citrata, kvascevog ekstrakta, CaCl2, PEG-400 i ekstrakta ovsa) i uslovi gajenja (vreme inkubacije, temperatura, količina inokuluma). U skladu sa faktorijalnim dizajnom izvedeno je osamnaest eksperimenata. Svaki faktor je ispitan na tri nivoa: -1 za donji nivo (granica), 0 za srednji nivo i +1 za gornji nivo. Medju ispitivanim faktorima, pozitivni efekat su imali saharoza, fruktoza, vreme inkubacije, amonijum-citrat, kvasčev ekstrakt i CaCl2. Prinos EPSa je bio u granicama od 0.56 do 21.02 g/l. Rezultati dobijeni statističkim dizajnom pokazuju da testirani soj ima visok potencijal za proizvodnju EPSa. Dalja optimizacija je predvidjena ispitivanjem faktora koji su pokazali pozitivan efekat pomocu druge statisticke metode – metode površine odziva.

In order to increase the yield of exopolysaccharides (EPS) production by natural isolate Leuconostoc sp. an investigation of the factors influencing the process was performed by Plackett-Burman design (Design Expert 8.0., trial version). The design was comprised eleven variables that can be classified into two groups of influences: the influence of the substrate (sucrose, glucose, fructose, ammonium citrate, yeast extract, CaCl2, PEG-400 and oat extract), and the influence of growing conditions (incubation time, temperature, amount of inoculum). Based on factorial design eighteen experiments were performed. Each factor was examined at three levels: -1 for low level, 0 for intermediate and +1 for high level. Among tested factors positive effect on exopolysaccharide yield had sucrose, ammonium -citrate, fructose, yeast extract, CaCl2 and incubation time. EPS yield varied from 0.56 to 21.02 g/l. The results from statistical design showed that tested strain has high potential for EPS production. Further optimization with positive factors should be done by the other statistical design technique - response surface methodology.