Optimizacija proizvodnje nizina v odpadni kisli sirotki

magistrsko delo

Neja Pristovšek (Author), Barbara Jeršek (Reviewer), Bojana Bogovič Matijašić (Mentor)

Abstract

Osiromašeno kislo sirotko iz proizvodnje skute, iz katere so predhodno odstranili laktoferin in del drugih proteinov, smo uporabili za gojenje seva Lactococcus lactis IM 145, ki proizvaja bakteriocin nizin Z. Za boljšo rast laktotokov smo ji dodali 2,5 % kvasnega ekstrakta. Bakteriocinsko aktivno biomaso smo pridobivali v treh šaržnih procesih v 2,5-L bioreaktorju. Vrednost pH smo na začetku preskusa uravnali na 6,5, med procesom pa vrednosti pH nismo uravnavali. Med fermentacijo smo poleg vrednosti pH spremljali še optično gostoto, število (KE/mL) ter protimikrobno aktivnost proti bakteriocinom občutljivemu sevu Latilactobacillus sakei subsp. sakei IM 108. Bakteriocinska aktivnost v supernatantu kulture je bila najvišja med 6. in 8. uro, kar sovpada z dosegom stacionarne faze rasti (KE/mL). Brozgo iz bioprocesa smo centrifugirali in iz supernatanta delno očistili nizin, s pomočjo ultrafiltracije, tekočinske kromatografije visoke ločljivosti z obrnjeno fazo in kationsko-izmenjevalne kromatografije. Čistost in funkcionalnost frakcij smo ugotavljali z NaDS-PAGE in s preskusi protimikrobne aktivnosti. Za najbolj učinkovit način čiščenja nizina se je izkazala kationsko-izmenjevalna kromatografija pri pH 6,0. Dokazali smo, da je kisla sirotka ustrezen medij za gojenje laktokokov, ki proizvajajo nizin Z in tako prikazali nov način njene izrabe, ki lahko prispeva k zmanjšanju odpadkov mlekarske industrije.

Keywords

kisla sirotka;odpadna sirotka;izolacija nizina;bakteriocini;laktokoki;RP-HPLC;protimikrobna aktivnost;bioreaktor;kationsko izmenjevalna kromatografija;

Data

Language:	Slovenian
Year of publishing:	2021
Typology:	2.09 - Master's Thesis
Organization:	UL BF - Biotechnical Faculty
Publisher:	[N. Pristovšek]
UDC:	637.344:602.42:604.4:615.33
COBISS:	65825795
Views:	429
Downloads:	61
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Optimisation of nisin production in waste acid whey
Secondary abstract:	Depleted acid whey from fresh curd cheese production, from which lactoferrin and part of other proteins were previously removed, was used for cultivation of Lactococcus lactis IM 145, bacteriocin nisin Z producing strain. 2,5 % yeast extract was added into the medium in order to stimulate the growth. Bacteriocin active biomass was produced in three batch processes in a 2,5-L bioreactor. At the beginning of the experiment pH was adjusted to 6,5 and was not regulated during the process. Beside pH, optical density and antimicrobial activity against bacteriocin sensitive strain Latilactobacillus sakei subsp. sakei IM 108 were monitored during fermentation. Bacteriocin activity was the highest after 6 to 8 h, which coincided with the stationary phase of growth (cfu/mL). After the fermentation broth was centrifuged, the nisin was isolated from the supernatant by ultrafiltration, reverse phase high performance liquid chromatography and cation-exchange chromatography. Purity and functionality of fractions were analysed by SDS-PAGE and antimicrobial activity tests. Cation-exchange chromatography at pH 6,0 was found to be the most efficient method for the purificiation of nisin. We confirmed that acid whey is a suitable medium for the cultivation of nisin Z producing lactococci and thus showed a new way of its usage which could contribute to the reduction of waste from the dairy industry.
Secondary keywords:	acid whey;waste whey;nisin isolation;bacteriocins;RP-HPLC;Lactococcus lactis;antimicrobial activity;bioreactor;cation exchange chromatography;
Type (COBISS):	Master's thesis/paper
Study programme:	0
Thesis comment:	Univ. v Ljubljani, Biotehniška fak., Oddelek za živilstvo
Pages:	XIII, 68 f., [2] f. pril.
ID:	12986056