The Influence of Different Factors on Manganese Incorporation into Saccharomyces cerevisiae

Yeast biomass as well as biomass enriched with trace minerals have been demonstrated to be useful in improving animal health and growth performance. In this work, process for the production of Saccharomyces cerevisiae biomass enriched with manganese, a microelement with antioxidant properties in the form of high bioavailable Mn-protein complex, has been studied. The influences of media composition, Mn2+ concentration and Mn salt were investigated in shaken cultures. The change of biomass and ethanol yields was not observed in molasses media with addition of Mn, while in sucrose media the decrease was observed at Mn2+ concentrations higher than 0.8 mM (added as sulphate) and 0.2 mM (added as chloride). It was established that aeration mode (anaerobic, shaken flask or aerated culture) influences amount and dynamic of Mn incorporation into the yeast biomass, and that this incorporation was S. cerevisiae strain dependent. The Fourier transform infrared (FTIR) spectrophotometry on blank and Mn loaded biomass suggested that carboxyl groups, N-H groups of secondary amide, and sulfonate groups are involved in mechanism of manganese binding

Yeast Trichosporon cutaneum on deproteinized whey in batch-wise and continued cultivation

Iz sirutke izdvojen kvasac Trichosporon cutaneum uzgaja se šaržno i kontinuirano u deproteiniziranoj sirutki pri pH 4,5-5,0 % temperaturi od 32 °C na tresilici i u laboratorijskom bioreaktoru. Uz dodatak diamonijevog sulfata i kalijevog hidrogen fosfata deproteiniziranoj sirutki kvasac Trichosporon cutaneum se dobro razmnožava pri svim istraživanim koncentracijama laktoze, a najbolja produktivnost procesa postiže se u podlozi sa 4% laktoze.Yeast Trichosporon cutaneum isolated from the whey has been cultivated on the rotary shaker and batch-wise or continuousely in the laboratory bio-reactor. Yeast T. cutaneum growed well at all studied concentrations of lactose in substrate, but the highest productivity of the process was achieved with 0,48-0,60 g DM/g lactose with the specific growth rate of 0,26 h^-1 and the productivity of 1,5 g/dm3/h

Production of single-cell proteins by yeast Kluyveromyces fragilis on whey

Studirana je mogućnost kultivacije kvasca Kluyveromyces fragilis za proizvodnju mikrobnih proteina na sirutci u šaržnom i kontinuiranom postupku pri pH 5,0-5,5 i temperaturi od 40 °C. Ustanovljeno je eksperimentima na tresilici i laboratorijskom fermentoru da se kvasac dobro razmnožava pri odabranim uvjetima okoline, na 2 %-tnoj deproteiniziranoj sirutci s dodatkom diamonijevog sulfata i kalijevog hidrogen fosfata. Pri optimalnim uvjetima okoline postiže se stupanj konverzije laktoze u kvaščevu biomasu od 0,45-0,55 g s. tv. kvasca/g laktoze, specifična brzina rasta do 0,25 sat^-1 i produktivnost procesa do 1,3 g/L/sat. Kada se osnovnom supstratu doda 0,1 % kvaščevog ekstrakta kvasac se razmnožava brže, specifična brzina rasta poraste na 0,35-0,38 sat^-1, a produktivnost procesa dostiže 1,8 g/L/sat. Ukoliko se voda, potrebna za razrjeđenje sirutke, zamijeni melasnom džibrom, postiže se također povećanje brzine rasta kvasca K. fragilis. Specifična brzina rasta bila je do 0,40 sat^-1, a produktivnost procesa od 2,0-2,4 g/L/satThe possibility of cultivation of the yeast Kluyveromyces fragilis for the production of single-cell protein on deproteinated whey was studied. The hatch and the continuous cultivations were performed at pH 5.0-5.5 and the temperature of 40 °C. By experiments on the shaker and in laboratory fermenter it was established that the yeast cells grow well on 2 % deproteinated whey with the addition of ammonium sulphate and potassium hydrogen phosphate. At optimal conditions the biomass yield was 0.45-0.55 g DM/g lactose with the specific growth rate up to 0.25 h^-1 and productivity of 1.3 g/L/h. When 0.1 % of the yeast extract was added to the basic medium the yeast cells were multiplying faster (μ = 0.35-0.38 h^-1) and productivity was up to 1.8 g/L/h. If the water necessary for the dilution of whey was exchanged with molasses slop a. very good effect attained in the cultivation of yeast cells. The specific growth rate was 0.4 h^-1 and productivity up to 2.4 g/L/h

Zinc, Copper and Manganese Enrichment in Yeast Saccharomyces cerevisae

The aim of the present work was to study the incorporation of some microelements in the yeast Saccharomyces cerevisiae and its impact on the physiological state of the yeast cells during the alcoholic fermentation. The cultivations were performed on molasses medium in anaerobic (thermostat) and semiaerobic (shaker) conditions, with and without the addition of zinc, copper and manganese sulphate (0.1 g/L of each) at 30 °C and different pH values of the medium (3.5–6.0) for 8 h. The addition of the mentioned salts in molasses medium enhanced the yield of the yeast biomass up to 30 % in semiaerobic conditions, but the ethanol yield was changed very little. On the other hand, in anaerobic conditions the yields of the yeast biomass were increased up to 10 % and alcohol yield up to 20 %. After the fermentations were performed, the concentration of metal ions in yeast cells was determined. Different values were achieved depending on the used growth conditions. The highest amount of Zn ions in dry matter (700 μg/g) was incorporated in the yeast biomass under anaerobic conditions. In contrast, the incorporation of Cu and Mn was preferred in semiaerobic conditions and the highest value of Cu2+ ions in dry matter (1100 μg/g) and Mn2+ in dry matter (300 μg/g) in yeast biomass were obtained. Optimal pH for all ion incorporations was between 4 and 5

Evolucija bakterija tijekom stacionarne faze rasta

Metagenomics and advances in molecular biology methods have enhanced knowledge of microbial evolution, metabolism, functions, their interactions with other organisms and their environment. The ability to persist and adapt to changes in their environment is a common lifestyle of 1 % of the known culturable bacteria. Studies in the variety of species have identified an incredible diversity of bacterial lifespan. The holy grail of molecular biology is to understand the integrated genetic and metabolic patterns of prokaryotic organisms like the enteric bacterium Escherichia coli. The usual description of E. coli life cycle comprises four phases: lag, logarithmic, stationary, and death phase, omitting their persistence and evolution during prolonged stationary phase. During prolonged stationary/starvation period, in batch bacterial culture, selected mutants with increased fitness express growth advantage in stationary phase (GASP), which enables them to grow and displace the parent cells as the majority population. The analyses of growth competition of Gram-negative and/or Gram-positive mixed bacterial cultures showed that GASP phenomenon can result in four GASP phenotypes: strong, moderate, weak or abortive. Bacterial stress responses to starvation include functions that can increase genetic variability and produce transient mutator state, which is important for adaptive evolution.Metagenomika i suvremene metode molekularne biologije omogućili su razumijevanje evolucije, metabolizma i funkcije mikroorganizama te njihovih interakcija s drugim organizmima u okolišu. Otpornost i prilagodba na promjene u okolišu uobičajeni su za 1 % poznatih bakterija što se mogu uzgajati u laboratoriju. Istraživanjem različitih bakterijskih vrsta uočena je njihova velika raznolikost. Escherichia coli je „sveti gral“ molekularne biologije u razumijevanju genetike i metaboličkih modela. Životni se ciklus E. coli sastoji od četiri faze: lag, logaritamske, stacionarne i faze odumiranja, zanemarujući bakterijsku postojanost i evoluciju tijekom produljene stacionarne faze. U šaržnoj bakterijskoj kulturi, tijekom produljene stacionarne faze ili vremena izgladnjivanja, preživjele stanice mutanata brže rastu (engl. growth advantage in stationary phase - GASP), pa prerastaju i zamjenjuju većinu roditeljskih stanica. Analiza kompetitivnoga rasta Gram-pozitivnih i/ili Gram-negativnih bakterija, tijekom produljene stacionarne faze u mješovitim kulturama, pokazala je postojanje četiriju GASP fenotipova: jaki, umjereni, slabi i nerazvijeni. Bakterijski odgovor na izgladnjivanje obuhvaća stanične funkcije koje mogu povećati genetičku raznolikost i stvarati mutator stanice bitne za adaptivnu evoluciju bakterija

Whey - raw material for the production of baker starter-cultures

U radu je ispitana mogućnost proizvodnje bakterija mliječne kiseline (BMK) prikladnih fizioloških karakteristika za pekarstvo na deproteiniziranoj sirutki te uspoređena s proizvodnjom na modificiranoj MRS podlozi. Istraženi su rast i fermentacijska aktivnost bakterija Leuconostoc mesenteroides L-3, Lactobacillus brevis L-62 i Lactobacillus plantarum L-73. Aktivnost navedenih BMK u fermentacijskim podlogama te kiselom tijestu praćena je mjerenjem količine nastale mliječne i octene kiseline. Iako je postignuta aktivnost BMK na sirutki manja nego na MRS, rezultati su pokazali da se deproteinizirana sirutka može koristiti kao osnovni supstrat u proizvodnji gore navedenih bakterija. Najveći prinos biomase (1,7 g/L) i proizvodnja mliječne kiseline (9,15 mg/mL) ostvareni su s bakterijom L. plantarum L-73. Ocjenjivanjem kruha utvrđeno je da su dodatkom startera priređenih na bazi starter-kultura uzgojenih na deproteiniziranoj sirutki poboljšani okus i miris, elastičnost kruha te njegova trajnost u usporedbi s kruhom proizvedenim klasičnim postupkom (uz dodatak monokulture pekarskog kvasca).The possibility of production Lactic acid bacteria (LAB), which are suitable for breadmaking on whey was researched and compared to the results achieved in modified MRS medium. The growth and fermentation activities of Leuconostoc meseteroides L-3, Lactobacillus brevis L-62 and Lactobacillus plantarum L-73 were examined by monitoring lactic and acetic acid production in fermentation broth and in sourdough. Presented results show that deproteinized whey is suitable for LAB production. The best biomass yield (1,7 g/L) and lactic acid production (9,15 mg/mL) was achieved with L. plantarum L-73. Better flavour, elasticity and shelf life of bread made with whey-based starters compared to the classical yeast-monoculture based bread were determined by sensory analysis (DLG method)

The influence of molasses addition on the kinetics of alcoholic fermentation of whey using Kluyveromyces marxianus yeast

U ovom radu praćena je kinetika alkoholne fermentacije pomoću kvasca Kluyveromyces marxianus ZIM 75 na podlogama sastavljenim od sirutke i melase. Fermentacije su provedene u statičkim i semiaerobnim uvjetima na temperaturi 34 °C, a za pripravu podloga korištene su deproteinizirana sirutka i melasa miješane u različitim omjerima tako da je ukupna koncentracija šećera u podlogama bila 5%, 10% i 15%. Provedeni pokusi pokazali su da je podloga koja je sadržavala 10% šećera (saharoza : laktoza = 1:1) optimalna za provođenje fermentacija u statičkim i u semiaerobnim uvjetima. Najbolji prinos etanola u statičkim uvjetima nakon 24 sata fermentacije iznosio je 4,05 % (V/V) dok je u semiaerobnim uvjetima iznosio 4,9 % (V/V). Prirast biomase također je bio bolji u semiaerobnim uvjetima i iznosio je 7,78 g s.tv./L, dok je u statičkim uvjetima prirast biomase iznosio je 3,19 g s.tv./L.Kinetics of alcoholic fermentation by yeast Kluyveromyces marxianus ZIM 75 in various media based on whey and molasses were monitored. The fermentations were performed under static and semiaerobic conditions at 34 °C. Deproteinized whey and molasses were mixed in various proportions to give final sugar mass concentrations of 5%, 10% and 15% in medium. The experiments conducted showed that medium with 10 % of sugar (sucrose:lactose=1:1) is optimal for alcoholic fermentations in static and semiaerobic conditions. The best ethanol yield after 24 hours of fermentation was 4.05 % (V/V) in static conditions and 4.9 % (V/V) in semiaerobic conditions. The biomass yield was 7.78 g d.m./L in semiaerobic conditions and 3.19 g d.m./L in static conditions

Hydrolysis of lactose with -D-galactosidase

U ovom radu su ispitivani uvjeti hidrolize laktoze pomoću enzimskog preparata -D-galaktozidaze, a svrha je - primjena sirutke u fermentativnim procesima s kvascem Saccharomyces cerevisiae za kombiniranu proizvodnju alkohola i prehrambenog kvasca. Enzimska hidroliza je provedena na različitim temperaturama, s različitim koncentracijama laktoze u podlozi i različitim količinama dodanog enzimskog preparata. Rezultati pokazuju da je maksimalni stupanj hidrolize postignut u podlozi koja je sadržavala 5-10 % laktoze s dodatkom 2 g/L enzimskog preparata na temperaturi od 40 ºC.The conditions of lactose hydrolysis with enzyme preparation of D-galactosidase were investigated. The aim of this work was to considered the use of whey in fermentative processes with yeast Saccharomyces cerevisiae. Enzymatic hydrolysis was conducted at different temperatures, with different lactose concentrations in medium and different concentrations of added enzyme. The results show that optimal temperature for hydrolysis was 40°C. The optimal amount of enzyme preparation was 2 gL-1 in lactose medium with 5-10 % lactose

Hydrolysis of lactose with -D-galactosidase

U ovom radu su ispitivani uvjeti hidrolize laktoze pomoću enzimskog preparata -D-galaktozidaze, a svrha je - primjena sirutke u fermentativnim procesima s kvascem Saccharomyces cerevisiae za kombiniranu proizvodnju alkohola i prehrambenog kvasca. Enzimska hidroliza je provedena na različitim temperaturama, s različitim koncentracijama laktoze u podlozi i različitim količinama dodanog enzimskog preparata. Rezultati pokazuju da je maksimalni stupanj hidrolize postignut u podlozi koja je sadržavala 5-10 % laktoze s dodatkom 2 g/L enzimskog preparata na temperaturi od 40 ºC.The conditions of lactose hydrolysis with enzyme preparation of D-galactosidase were investigated. The aim of this work was to considered the use of whey in fermentative processes with yeast Saccharomyces cerevisiae. Enzymatic hydrolysis was conducted at different temperatures, with different lactose concentrations in medium and different concentrations of added enzyme. The results show that optimal temperature for hydrolysis was 40°C. The optimal amount of enzyme preparation was 2 gL-1 in lactose medium with 5-10 % lactose