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

Mikrobiološka kvaliteta komercijalnog pekarskog kvasca na hrvatskom tržištu

Komercijalni pekarski kvasac je aktivna biomasa kvasca Saccharomyces cerevisiae kojoj se tijekom procesa proizvodnje, distribucije i skladištenja pridružuju i drugi nenamjenski mikroorganizmi. U radu je ispitana mikrobiološka kvaliteta uzoraka svježih i suhih oblika pekarskog kvasca različitih proizvođača prisutnih na hrvatskom tržištu. Za izolaciju i identifikaciju mikrobne populacije u uzorcima pekarskog kvasca upotrijebljene su klasične mikrobiološke metode, a mikrobni rast određen je brojanjem poraslih kolonija na selektivnim hranjivim podlogama. Rezultati su pokazali da su bakterije mliječne kiseline (BMK) dominantni pridruženi mikroorganizmi pekarskom kvascu, prisutni u koncentraciji od 105 - 108 st/g. U uzorcima kvasca dokazani su i divlji kvasci i koliformne bakterije u koncentraciji od 103, odnosno 104st/g. Suhi pekarski kvasac imao je bolju mikrobiološku kvalitetu budući da u uzorcima nisu dokazane plijesni i bakterija Listeria monocytogenes. Salmonella sp. i Escherichia coli nisu dokazane u nijednom uzorku, dok je Staphylococcus aureus dokazan u 89% uzoraka svježeg te 67% uzoraka suhog kvasca u koncentraciji od oko 101 st/g

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

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)

Potential of bacteria for bioethanol production from lignocellulosic raw materials

Poljoprivreda, šumarstvo i prehrambena industrija izvori su velike količine lignocelulozne biomase, koja može poslužiti kao lako dostupna i jeftina obnovljiva sirovina za dobivanje različitih bioproizvoda. Jedan od takvih proizvoda je i bioetanol. Ovaj rad daje pregled bakterija koje se koriste i/ili istražuju za proizvodnju bioetanola iz lignoceluloznih sirovina. U navedenim istraživanjima proizvodnje bioetanola pomoću bakterija primijenjuju se različiti pristupi kako bi se povećala ekološka i ekonomska efikasnost procesa. Pored uobičajenih bioprocesa, koji se provode u više faza i uz pomoć monokulture, razvijaju se i visokointegrirani (konsolidirani) bioprocesi uz primjenu mikrobnih kokultura.Agriculture, forestry and food industry are sources of large quantities of lignocellulosic biomass, which can be used as an easily accessible and cheap renewable raw material for production of different bioproducts. One of these bioproducts is also bioethanol. This paper provides an overview of bacteria used and/or investigated for bioethanol production from lignocellulose-containing feedstocks. In the research of bioethanol production using bacteria, various approaches are applied in order to increase ecological and economic efficiency of bioprocess. In addition to conventional multi-stage bioprocesses that are carried out using monoculture, highly integrated (consolidated) bioprocesses and applications of microbial cocultures are also in developing stage

Characterization of a S-adenosyl-l-methionine (SAM)-accumulating strain of Scheffersomyces stipitis

S-adenosyl-l-methionine (SAM) is an important molecule in the cellular metabolism of mammals. In this study, we examined several of the physiological characteristics of a SAM-accumulating strain of the yeast Scheffersomyces stipitis (M12), including SAM production, ergosterol content, and ethanol tolerance. S. stipitis M12 accumulated up to 52.48 mg SAM/g dry cell weight. Proteome analyses showed that the disruption of C-24 methylation in ergosterol biosynthesis, a step mediated by C-24 sterol methyltransferase (Erg6p), results in SAM accumulation by S. stipitis M12 compared to the wild-type strain. A comparative proteome-wide analysis identified 25 proteins that were differentially expressed by S. stipitis M12. These proteins are involved in ribosome biogenesis, translation, the stress response, ubiquitin-dependent catabolic processes, the cell cycle, ethanol tolerance, posttranslational modification, peroxisomal membrane stability, epigenetic regulation, the actin cytoskeleton and cell morphology, iron and copper homeostasis, cell signaling, and energy metabolism. [Int Microbiol 2015; 18(2):117-125]Keywords: Scheffersomyces stipitis · S-adenosyl- l-methionine (SAM) · SAM accumulating yeast · C-24 sterol methyltransferase (Erg6p

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

Whey – an optional raw material for food yeast production

U ovom radu ispitivani su utjecaji koncentracije laktoze u podlozi i aerobnosti procesa na prirast biomase kvasca Kluyveromyces marxianus na sirutki. U tu svrhu provedeni su šaržni procesi uzgoja u laboratorijskom bioreaktoru od 2L kvascem Kluyveromyces marxianus ZIM75 s različitim koncentracijama laktoze u podlozi i s različitim protocima zraka. Najbolji prirast biomase ostvaren je u procesu s najvećim protokom zraka od 1,5 L/L min i u podlozi s 10% laktoze, a iznosio je 5,90 g s.tv./L. S povećanjem protoka zraka rasla je i specifična brzina rasta, te je najveća vrijednost od 0,1060 h-1 postignuta pri najvećem protoku zraka i u podlozi s 5% laktoze. Iskorištenje supstrata ipak je bilo bolje u podlozi s 5% laktoze (0,104 g/g).The influence of the lactose content in the medium and of the air flow rate on the biomass yield of the yeast Kluyveromyces marxianus on whey substrate was investigated. For this purpose, batch processes were conducted in a laboratory bioreactor (2L) with the yeast Kluyveromyces marxianus ZIM75 in media with different contents of lactose and at different air flow rates. The higest biomass yield (5,9 g d.m./L) was achieved at the highest air flow rate (1,5 L/L min) in the medium with 10% of lactose. The specific growth rate increased with increased air flow rate, and the highest specific growth rate of 0,1060 h-1 was achieved at the highest air flow rate in the medium with 5% of lactose. However, the best conversion of lactose carbon to biomass (0,104 g/g) was achieved in the medium with 5% of lactose

S-adenosyl-L-methionine production by an ergosterol-deficient mutant of Scheffersomyces stipitis

S-adenosyl-L-methionine (SAM, SAMe; AdoMet) is an important methyl donor in many reactions, and recently has attracted much attention due to its expanding application in pharmacy. Efficient ways of its production have been widely researched. In this study it was demonstrated that erg6 mutant of yeast Scheffersomyces stipitis (former Pichia stipitis), obtained by UV mutagenesis and selected by resistance to nystatin, could be used for production of SAM. The mutant strain showed higher ability to accumulate SAM than its parental strain. The experiments demonstrated different dependence of erg6 mutant strain on several cultivation conditions in comparison to parental strain, its higher sensibility to oxidative stress, as well as strong dependence of SAM accumulation on the cell growth phase and supplementation of growth media with methionin

Potencijalno mjesto vezanja estrogena na S protein virusa SARS-CoV2

Research background. During the current SARS-CoV2 pandemic, as well as earlier SARS and MERS epidemics, it has been observed that COVID19-positive women on average tend to have milder symptoms and lower fatality rates than men. There is a number of differences between the sexes known to contribute to different immune responses and severity of the disease, one being the effect of estrogen via estrogen receptor signalling. We wondered if estrogen might also affect the SARS-CoV2 more directly, perhaps by binding to the surface glycoprotein (S protein), thus possibly reducing its infectivity. Experimental approach. To assess whether there is a possibility for estrogen binding on the SARS-CoV2 S protein, we used BLAST and HHpred to compare protein sequences of S protein and human estrogen receptor β, while 3D structures of a potential estrogen binding site and an active site of estrogen receptor β were visualized and compared using PyMOL. Results and conclusions. By comparing the sequence of SARS-CoV2 S protein with the human estrogen receptor β, we identified a potential estrogen binding site on S protein and further determined that it also shares notable similarities with the active site of ER β when observed in 3D structure of their respective proteins. As a control, SARS-CoV2 S protein was compared with the human androgen receptor, and no such similarities were found. The potential estrogen binding site is part of coronavirus S2 superfamily domain, which is involved in host-virus membrane fusion during infection and appears to be conserved throughout the Coronaviridae family. Novelty and scientific contribution. This preliminary communication shows that SARS-CoV2 S protein features a potential estrogen binding site. Hopefully, this will prompt a more comprehensive study on the possibilities of estrogen binding on the S protein and the effect this might confer on the virus infectivity.Pozadina istraživanja: Tijekom trenutne SARS-CoV2 pandemije, ali i ranijih epidemija virusa SARS i MERS, primijećeno je da žene oboljele od COVID-19 imaju u prosjeku blaže simptome bolesti, te niži postotak smrtnosti od muškaraca. Poznato je da niz faktora pridonosi različitom imunološkom odgovoru i težini bolesti između spolova. Između ostalog, na sam imunološki odgovor utječe prisutnost hormona estrogena u organizmu i to posrednim djelovanjem preko signalnog puta receptora za estrogen. Međutim, postavili smo pitanje je li moguće da estrogen djeluje direktno na virus SARS-CoV2, i to možda vezanjem na glikoprotein na površini virusne čestice (S protein), čime bi se mogla umanjiti infektivnost virusa. Eksperimentalni pristup: Radi procjene mogućnosti vezanja estrogena na S protein virusa SARS-CoV2 usporedili smo proteinske sekvence S proteina i humanog estrogen receptora β pomoću alata BLAST i HHpred, a 3D strukture potencijalnog mjesta za vezanje estrogena na S proteinu i aktivnog mjesta estrogen receptora β vizualizirali smo i usporedili pomoću programskog alata PyMOL. Rezultati i diskusija: Usporedbom sekvence S proteina virusa SARS-CoV2 sa sekvencom humanog estrogen receptora β, identificirali smo moguće mjesto vezanja estrogena na S proteinu, a promatranjem njihovih 3D struktura utvrdili veliku sličnost tog aktivnog mjesta s aktivnim mjestom ER β. S protein virusa SARS-CoV2 uspoređen je s humanim androgen receptorom radi kontrole dobivenih rezultata, no nije utvrđena sličnost među njima. Potencijalno mjesto vezanja estrogena dio je domene S2 koja sudjeluje u fuziji membrana virusa i stanice domaćina tijekom infekcije, te je konzervirana u virusima iz porodice Coronaviridae. Novina i znanstveni doprinos: U ovom prethodnom priopćenju prikazana je mogućnost da S protein virusa SARS-CoV2 nosi mjesto za vezanje estrogena. Ovo saznanje moglo bi potaknuti provedbu sveobuhvatnije studije stvarnih mogućnosti vezanja estrogena na S protein i eventualnog učinka koji bi to moglo imati na infektivnost virusa