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Journal, Genetic Engineering &... Jun 2020Probiotic strains are incorporated into food substrates to contribute to fermentation process. The technological suitability of such strains to improve the flavor and...
BACKGROUND
Probiotic strains are incorporated into food substrates to contribute to fermentation process. The technological suitability of such strains to improve the flavor and nutritional value of fermented food is strain-specific. Potentially probiotic yeasts isolated from Nigerian traditional fermented foods were assessed for production of volatile compounds by gas chromatography-mass spectrophotometry. Phytases were characterized for activity and stability at different pH (3-8) and temperatures (25-50 °C).
RESULTS
A total of 45 volatiles compounds were identified from intracellular cell-free extracts of Pichia kluyveri LKC17, Issatchenkia orientalis OSL11, P. kudriavzevii OG32, P. kudriavzevii ROM11, and Candida tropicalis BOM21. They include alcohols (14), carbonyls (13), esters (10), and organic acids (8). Phenylethyl alcohol was the highest higher-alcohol in Issatchenkia orientalis OSL11 (27.51 %). The largest proportion of esters was detected in P. kudriavzevii OG32 (17.38 %). Pichia kudriavzevii OG32 and C. tropicalis BOM21 showed vigorous gowth in minimal medium supplemented with sodium phytate (2 g L). Extracellular phytases from P. kudriavzevii OG32 and Candida tropicalis BOM2 showed optimal activiy at pH 4.6 (104.28 U) and pH 3.6 (81.43 U) respectively.
CONCLUSIONS
Results obtained revealed species- and strain-specific potentials of the yeast strains to improve flavor and mineral bioavailability of fermented food products. Therefore, the application of these yeasts as starter cultures during food fermentation process is a very promising method to enhance the flavor profile and enhance mineral bioavailability in indigenous cereal-based fermented food products.
PubMed: 32507932
DOI: 10.1186/s43141-020-00031-z -
Food Chemistry Oct 2020In the present work we aimed to demonstrate the influence of inoculum starter in support high quality fermentation. Cocoa fermentations were performed in wooden boxes...
In the present work we aimed to demonstrate the influence of inoculum starter in support high quality fermentation. Cocoa fermentations were performed in wooden boxes and eight yeasts strains were used in separated fermentations of fine cocoa, type Scavina, as starter inoculum. Temperature, pH, titirable acidity, reducing sugar and free amino acids were evaluated during or after fermentation. The influence of starters yeasts on the decrease of acidity, sugar concentration and free amino acids was significant. The strains Candida parapsilosis, Torulaspora delbrueckii and Pichia kluyveri showed greater changes in the reducing sugar and free amino acids in fermented cocoa beans. These results indicate the ability of yeast used as inoculum starter to modify the end condition and further enhance the quality of fine cocoa beans.
Topics: Amino Acids; Cacao; Candida parapsilosis; Chocolate; Fermentation; Food Microbiology; Hydrogen-Ion Concentration; Pichia; Seeds; Temperature; Torulaspora; Yeasts
PubMed: 32464557
DOI: 10.1016/j.foodchem.2020.127110 -
Antimicrobial Agents and Chemotherapy Jun 2020Manogepix (APX001A) is the active moiety of the novel drug candidate fosmanogepix (APX001). We previously reported the broad-spectrum activity of manogepix but also...
Manogepix (APX001A) is the active moiety of the novel drug candidate fosmanogepix (APX001). We previously reported the broad-spectrum activity of manogepix but also observed a correlation between increased manogepix and fluconazole MICs. Here, we extended this study and included isolates with acquired fluconazole resistance. Isolates ( = 835) were identified using CHROMagar, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and, when needed, internal transcribed spacer (ITS) sequencing. EUCAST E.Def 7.3.1 susceptibility testing included manogepix, amphotericin B, anidulafungin, micafungin, fluconazole, and voriconazole. Manogepix wild-type-upper-limit (WT-UL) values were established following EUCAST principles for the epidemiological cutoff value (ECOFF) setting allowing wild-type/non-wild-type classification. Drug-specific MIC correlations were investigated using Pearson's correlation. Manogepix modal MICs were low (range, 0.004 to 0.06 mg/liter against 16/20 included species). Exceptions were and and, to a lesser extent, and The activity was independent of Fks echinocandin hot spot alterations ( = 17). Adopting the WT-UL established for , , , , and , 14/724 (1.9%) isolates were non-wild type for manogepix. Twelve of these (85.7%) were also non-wild type for fluconazole. A statistically significant correlation was observed between manogepix and fluconazole MICs for , , , , and (Pearson's = 0.401 to 0.575) but not between manogepix and micafungin or amphotericin B MICs for any species except ( = 0.519 for manogepix versus micafungin). Broad-spectrum activity was confirmed for manogepix against contemporary yeast. However, a 1 to 4 2-fold dilutions increase in manogepix MICs is observed in a subset of isolates with acquired fluconazole resistance. Further studies on the potential underlying mechanism and implication for optimal dosing are warranted.
Topics: Aminopyridines; Antifungal Agents; Candida; Drug Resistance, Fungal; Fluconazole; Humans; Isoxazoles; Kluyveromyces; Microbial Sensitivity Tests; Pichia
PubMed: 32366708
DOI: 10.1128/AAC.00429-20 -
Mycobiology 2020Citric acid is a commercially valuable organic acid widely used in food, pharmaceutical, and beverage industries. In this study, 260 yeast strains were isolated from...
Citric acid is a commercially valuable organic acid widely used in food, pharmaceutical, and beverage industries. In this study, 260 yeast strains were isolated from soil, bread, juices, and fruits wastes and preliminarily screened using bromocresol green agar plates for their ability to produce organic acids. Overall, 251 yeast isolates showed positive results, with yellow halos surrounding the colonies. Citric acid production by 20 promising isolates was evaluated using both free and immobilized cell techniques. Results showed that citric acid production by immobilized cells (30-40 g/L) was greater than that of freely suspended cells (8-19 g/L). Of the 20 isolates, two (KKU-L42 and KKU-L53) were selected for further analysis based on their citric acid production levels. Immobilized KKU-L42 cells had a higher citric acid production rate (62.5%), while immobilized KKU-L53 cells showed an ∼52.2% increase in citric acid production compared with free cells. The two isolates were accurately identified by amplification and sequence analysis of the 26S rRNA gene D1/D2 domain, with GenBank-based sequence comparison confirming that isolates KKU-L42 and KKU-L53 were and , respectively. Several factors, including fermentation period, pH, temperature, and carbon and nitrogen source, were optimized for enhanced production of citric acid by both isolates. Maximum production was achieved at fermentation period of 5 days at pH 5.0 with glucose as a carbon source by both isolates. The optimum incubation temperature for citric acid production by was 32 °C, with NHCl the best nitrogen source, while maximum citric acid by was observed at 27 °C with (NH) SO as the nitrogen source. Citric acid production was maintained for about four repeated batches over a period of 20 days. Our results suggest that apple and banana wastes are potential sources of novel yeast strains; and which could be used for commercial citric acid production.
PubMed: 32363040
DOI: 10.1080/12298093.2020.1726854 -
Frontiers in Microbiology 2019Effects of wine and dairy yeast fermentation on chemical constituents of tilapia fish head hydrolysate supplemented with glucose in an unsalted and acidic environment...
Effects of wine and dairy yeast fermentation on chemical constituents of tilapia fish head hydrolysate supplemented with glucose in an unsalted and acidic environment were investigated. Three wine yeasts ( Biodiva, Lalvin EC-1118 and Frootzen) and one dairy yeast ( NCYC1425) were employed as single starter cultures, respectively, and were compared with one soy sauce yeast ( NCYC1433). Each yeast showed different growth kinetics and fermentation performance. Compared with NCYC1433, other yeasts presented a significant higher rate of glucose consumption ( < 0.05). Besides, NCYC1425 and Frootzen produced more citric acid and succinic acid, respectively, while Lalvin EC-1118 exhibited higher pyruvic acid production. Significant lower levels of total free amino acids were observed in samples inoculated with wine yeasts relative to other yeasts ( < 0.05). Non-soy sauce yeasts produced increased various levels of esters and alcohols without traditional fish sauce unpleasant odorants, especially NCYC1425 and Frootzen. The results confirmed that non-soy sauce yeasts are suitable for fish sauce flavor compound modification and to develop a fast fermentation process for saltless fish sauce from fish head, which could increase the acceptability of fish sauce and improve the utilization of fish by-products.
PubMed: 31649641
DOI: 10.3389/fmicb.2019.02300 -
Foods (Basel, Switzerland) Oct 2019Undesired fermentation of fruit-derived beverages by fungal, yeast and bacterial spoilage organisms are among the major contributors of product losses in the food...
Undesired fermentation of fruit-derived beverages by fungal, yeast and bacterial spoilage organisms are among the major contributors of product losses in the food industry. As an alternative to chemical preservatives, the use of and was assessed for antimicrobial activity against several yeasts () and fungi (, and ) associated with spoilage of fruit and fruit-derived beverages. The antagonistic properties of and were evaluated on cheap solidified medium (grape pomace extract) as well as on fruits (grapes and apples). Volatile organic compounds (VOCs) from and deemed to have antimicrobial activit were identified by gas chromatography-mass spectrometry (GC-MS). A cell suspension of and showed growth inhibition activity against all spoilage microorganisms studied. Direct contact and extracellular VOCs were two of the mechanisms of inhibition. Twenty-five VOCs belonging to the categories of alcohols, organic acids and esters were identified as potential sources for the biocontrol activity observed in this study. This study reports, for the first time, the ability of to inhibit fungal growth and also for to show growth inhibition activity against spoilage organisms ( = 6) in a single study.
PubMed: 31590435
DOI: 10.3390/foods8100454 -
Microorganisms Jun 2019The goal of this study is to assess to what extent non- yeasts can introduce aromatic changes of industrial interest in fermentative, varietal and aged aromas of wine....
The goal of this study is to assess to what extent non- yeasts can introduce aromatic changes of industrial interest in fermentative, varietal and aged aromas of wine. Aroma precursors from Riesling and Garnacha grapes were extracted and used in two independent sequential experiments. Synthetic musts were inoculated, either with (Sc) or with (Pk), (Td) or (Lt), followed by Sc. The fermented samples were subjected to anoxic aging at 50 °C for 0, 1, 2 or 5 weeks before an aroma analysis. The fermentative aroma profiles were consistently changed by non-: all strains induced smaller levels of isoamyl alcohol; Pk produced huge levels of aromatic acetates and can induce high levels of fatty acids (FA) and their ethyl esters (EE); Td produced large levels of branched acids and of their EE after aging, and induced smaller levels of FA and their EE; Lt produced reduced levels of FA and their EE. The varietal aroma was also deeply affected: TDN (1,1,6-trimethyl-1,2- dihydronaphthalene) levels in aged wines were reduced by Pk and enhanced by Lt in Garnacha; the levels of vinylphenols can be much reduced, particularly by Lt and Pk. TD and Lt can increase linalool and geraniol in young, but not in aged wines.
PubMed: 31174281
DOI: 10.3390/microorganisms7060164 -
Foods (Basel, Switzerland) Feb 2019Microbial spoilage causes food losses in the food industry and as such, the use of synthetic chemical preservatives is still required. The current study proposes the use...
Microbial spoilage causes food losses in the food industry and as such, the use of synthetic chemical preservatives is still required. The current study proposes the use of agro-waste, i.e., grape pomace extracts (GPE), as production medium for biopreservation compounds. Production kinetics, subsequent to optimization using response surface methodology (RSM) for biopreservation compounds production was studied for three yeasts using GPE broth as a fermentation medium. The results showed that the highest volumetric zone of inhibition (VZI) was 1.24 L contaminated solidified media (CSM) per mL biopreservation compounds used (BCU) when Y1117 was inoculated in a pH 3-diluted GPE broth (150 g L) incubated at 25 °C for 24 h. Similar conditions were applied for Y1125 and Y1164, albeit under slightly elongated fermentation periods (up to 28 h), prior to the attainment of a maximum VZI of only 0.72 and 0.76 L CSM mL ACU, respectively. The potential biopreservation compounds produced were identified to be isoamyl acetate, isoamyl alcohol, 2-phenyl ethylacetate and 2-phenyl ethanol.
PubMed: 30717320
DOI: 10.3390/foods8020051 -
International Journal of Food... Jan 2019The aim of this study was to characterize the yeast consortium isolated from Grignolino grapes in a newly planted vineyard in Piedmont (Italy) via analysis of the...
The aim of this study was to characterize the yeast consortium isolated from Grignolino grapes in a newly planted vineyard in Piedmont (Italy) via analysis of the intra-vineyard yeast distribution of grape samples from single rows. A two-phase approach allowed the identification of culturable yeasts present on grape skins and, through an enriching procedure via grape fermentation, the isolation of low frequency non-Saccharomyces and Saccharomyces spp. fermentative species, including S. paradoxus, which is highly unusual during grape fermentation, along with the intra-specific characterization of S. cerevisiae isolates. Culture-based molecular techniques revealed a grape yeast microbiota formed by (in order of abundance) Hanseniaspora uvarum, the yeast-like fungus Aerobasidium pullulans, Candida zemplinina, Pichia kluyveri, Candida californica, Curvibasidium cygneicollum, Meyerozima caribbica, Rhodotorula babjevae, Metschnikowia pulcherrima and Cryptococcus flavescens. Technological properties of isolated Saccharomyces spp. strains were analysed, identifying strains, including S. paradoxus, potentially suitable as an ecotypical starter for territorial wines.
Topics: Biodiversity; Farms; Fermentation; Hanseniaspora; Italy; Saccharomyces; Saccharomyces cerevisiae; Vitis; Wine; Yeasts
PubMed: 30245288
DOI: 10.1016/j.ijfoodmicro.2018.09.016 -
Yeast (Chichester, England) Oct 2018Antagonistic yeasts suppress plant pathogenic fungi by various mechanisms, but their biocontrol efficacy also depends on the ability to compete and persist in the...
Antagonistic yeasts suppress plant pathogenic fungi by various mechanisms, but their biocontrol efficacy also depends on the ability to compete and persist in the environment. The goal of the work presented here was to quantify the composition of synthetic yeast communities in order to determine the competitiveness of different species and identify promising candidates for plant protection. For this purpose, colony counting of distinct species and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS; MALDI biotyping) were used to distinguish different yeast species and to quantify the composition of a synthetic community of six yeasts (Aureobasidium pullulans, Candida subhashii, Cyberlindnera sargentensis, Hanseniaspora sp., Metschnikowia pulcherrima and Pichia kluyveri) over time, on apples and in soil, and in different growth media. These studies revealed important characteristics that predispose the different species for particular applications. For example, the competitiveness and antagonistic activity of C. subhashii was strongly increased in the presence of N-acetylglucosamin as the sole carbon source, M. pulcherrima and A. pullulans were the strongest competitors on apple, and C. sargentensis competed the best in soil microcosms. Based on these laboratory studies, M. pulcherrima and A. pullulans are promising candidates for biocontrol applications against fungal phyllosphere diseases, while C. sargentensis may hold potential for use against soilborne fungal pathogens. These results document the potential of MALDI-TOF MS for the quantitative analysis of synthetic yeast communities and highlight the value of studying microorganisms with relevant functions in moderately complex, synthetic communities and natural substrates rather than as individual isolates.
Topics: Antibiosis; Biological Control Agents; Candida; Culture Media; Malus; Microbial Consortia; Pichia; Saccharomyces cerevisiae; Soil Microbiology; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Yeasts
PubMed: 29752875
DOI: 10.1002/yea.3321