Some studies on Nigerian palm wine with special reference to yeasts

The identification and enumeration of yeasts and the effect of chemical preservatives on the yeast load in Nigerian palm wine have been studied. Yeast found largely belong to the genus Saccharomyces. Other genera found were Candida, Endomycopsis, Hansenula, Kloeckera, Pichia, Saccharomycoides and Schizosaccharomyces. The viable yeast count ranged from 0.5 × 10⁷ cfu/ml to 4.2 × 10⁹ in both fresh Elaeis and Raphia spp. of palms. Yeasts in palm wine were least sensitive to sodium nitrate and most sensitive to sodium benzoate. The addition of these two chemical preservatives amongst others reduced the yeast count to 3.2 × 10⁸ (in Raphia sp.), and 4.1 × 10⁹ (in Elaeis sp.) with 0.025% sodium nitrate and 1.2 × 10⁶ (in Raphia sp.) and 1.9 × 10⁷ (in Elaeis sp.) with 0.1% sodium benzoate. The values of the yeast count in bottled and fresh palm wine were between 1.3 × 10³ cfu/ml to 9.8 × 10⁶ and 0.5 × 10⁷ to 4.2 × 10⁹, respectively. Maximum values of actual dry and theoretical yeast weights were 1.09 and 42 mg/ml, respectively.     

High level ethanol-tolerant Saccharomyces from Nigerian palm wine

Summary Eight Saccharomyces yeasts isolated from Nigerian palm wine showed high tolerance to 18% ethanol v/v and 50% sucrose. Two of the yeasts produced 12.7 and 13.1% ethanol v/v in 50% sucrose supplemented YPD-2. Soybean and groundnut supplementations yielded up to 21.5% and 19.0% ethanol v/v respectively.     

A note on a selective medium for wine yeasts

The numerical assessment of wine yeast in the presence of excessive numbers of apiculate yeasts has been attempted by the use of a differential medium. Medium ESY containing 150 mg/l bisulphite and 12% by volume of ethanol (pH 5·5) was found suitable for the enumeration of wine yeasts when present even at low concentrations in the natural microflora during the early stages of a grape juice fermentation. Apiculate yeasts seem to persist longer at low fermentation temperatures.     

Characterization of yeasts isolated from red wine surface film

We have isolated 6 morphologically different axenic yeast cultures from the film surface of red wine. Based on morphological, physiological and biochemical characteristics we have identified the strains as follows: isolates1–4 are morphologically different strains of the anamorph basidiomycetous film-forming yeastCandida humicola (Daszewska) Diddens etLodder, syn.Apiotrichum humicola (Daszewska) von Arx Weijman. Isolates5 and6 belong to the genusSaccharomyces of the associated speciesS. cerevisiœ (isolate5 originallyS. bayanus, isolate6 S. capensis). These do not participate in the surface film formation.     

Use of high-ethanol-resistant yeast isolates from Nigerian palm wine in lager beer brewing

High-ethanol-resistant yeasts, characterized as Saccharomyces sp., were isolated from Nigerian palm wine with added sucrose for high gravity brewing. The yeast isolates that survived the highest ethanol production were used to ferment brewery wort and produced 8.2 to 8.5% (v/v) ethanol; values almost double that of the control yeast from a local brewery.     

崇明老白酒酿造过程中酵母菌的鉴定及其特性初探

从八二酒曲及酿造崇明老白酒过程中分离纯化得到1株白色酵母菌和1株红色酵母菌,采用分子生物学方法进行鉴定,并对其酿造老白酒的特性进行了分析。结果显示,八二酒曲及崇明老白酒酿造过程中的优势酵母菌为酿酒酵母(Saccaromyces cerevisiae),从酿酒过程中分离的红色酵母菌为粘红酵母(Rhodotorula mucilaginosa)。采用粘红酵母和米根霉曲酿造的酒液的酒精度为11.9%vol,残余还原糖含量为11.2 g/100 m L,总酸含量为4.59 g/L,总酯含量为4.42 g/L。纯化的酿酒酵母和米根霉曲酿成的酒液口味醇和爽口,酒曲的纯化有助于开发出口感更爽口的老白酒。混合酵母和米根霉曲酿造的酒液呈典型的崇明老白酒风味,粘红酵母的参与对崇明老白酒口味风格的形成有一定的作用。     

Production of wine from mango (Magnifera indica L.) using Saccharomyces and Schizosaccharomyces species isolated from palm wine

Juice extracted from pulp of the mature ripe tropical fruit, mango ( Magnifera indica L.), containing 15.9% soluble solids, was fermented with four strains of yeast isolated from palm wine. Two of the strains belonged to the genus Schizosaccharomyces (T1 and T2) while the other two were Saccharomyces (B2 and M1). The two strains of Schizosaccharomyces were found to be suitable for the production of sweet, table mango wine with alcohol contents of 8.0 and 9.0% for T1 and T2, respectively. The two strains of Saccharomyces were found suitable for the production of dry mango fruit wines containing 10.0% alcohol.     

Development of baking yeast from Nigerian palm-wine yeasts

Two local strains of Saccharomyces cerevisiae, Nk, and Nk₂, showed leavening activities of 103% and 102% of that of a commercial yeast strain on wheat flour and of 114% and 113% on composite dough with 40% (w/v) maize substitution. Yeast fusion products Nk/Ng, Nk/Nk₁ and Nk/Nk₂ showed activities of 104% to 113% on wheat flour and 111% to 131% on the composite dough. These advantages were maintained in the yeasts' baking properties and organoleptic qualities. The fusion products also showed enhanced osmotic tolerance, as indicated by good growth in 3%, 6% and 10% (w/v) NaCl and 50% (w/v) glucose. Viability of the fusion products, preserved by drying at 30 to 35°C, dropped to between 62% and 72% after 3 months.A.O. Ejiofor was and N. Okafor and E.N. Ugwueze are with the Department of Applied Microbiology and Brewing, Nnamdi Azikiwe University, P.M.B. 5025, Awka, Nigeria. A.J. Ejiofor is now with the Abteilung Biovertahrenstechnik, Gesellschaft für Biotechnologische Forschung, Mascheroder Weg 1, D-38124 Braunschweig, Germany     

Enzymatic activity of micro-organisms isolated from cork wine stoppers

The production of enzymes by micro-organisms which are found on vegetal substrates is important due to their ability to decompose cellulose, lignin and other components, which guarantee the integrity of the vegetal cell. The objective of this study was to determine the enzymatic activity of filamentous fungi, yeasts and bacteria, isolated from natural cork stoppers for bottles of still and sparkling wines. Suspensions of fungal conidia, yeasts and bacterial cells of micro-organisms were established in concentrations of 10(6) CFU/ml. The enzymatic activity of these micro-organisms was evaluated by means of the API ZYM system, with which it was possible to determine and semi-quantify nineteen enzymatic activities simultaneously. The enzymes produced by all of the species were esterase (C1), esterase lipase and naphthol-AS-BI-phosphohydrolase. The micro-organisms with the greatest enzymatic activity were Monilia sitophila, Alternaria alternata, Aspergillus niger and Aeromonas sp.     

Biodiversity of killer activity in yeasts isolated from the Brazilian rain forest

The occurrence of killer activity against a panel composed of 22 industrially and (or) medically important yeasts was investigated in 438 yeast and yeast-like cultures belonging to 96 species, isolated from different environments of the Brazilian rain forest. Altogether, 26% of ascomycetes, 56% of basidiomycetes, and 42% of yeast-like cultures exhibited killer activity against at least one of the panel yeasts. More than 15 species never reported before as toxin producers were found, with Pseudozyma antarctica, Trichosporon asteroides, and Geotrichum klebahnii, showing the broader activity spectra. Plasmid curing did not cure the killer phenotypes of Candida maltosa, Debaryomyces hansenii, G. klebahnii, Tr. asteroides, Cryptococcus laurentii, and Ps. antarctica.     

Pectinolytic activity secreted by yeasts isolated from fermented citrus molasses

AIMS: The aim of this study was to obtain improved strains of pectinolytic yeasts adapted to the conditions of an industrial fermentation process, which was continuously operated to convert citrus molasses into ethanol. METHODS AND RESULTS: The starter yeast of the industrial fermentation process was a commercial baker's yeast, which was capable of growing without forming any secretion halo of pectinase activity on solid medium. Nevertheless, isolates showing secretion of pectinolytic activity on plates were obtained from the fermentation process. The secretion of pectin-degrading activity by isolates on plates was repressed by galactose and improved as the result of colony aging on polygalacturonic acid plates at 30 degrees C. Liquefaction of polygalacturonate gels as well as the splitting of the pectin-degrading activity into a wall-linked and a supernatant fraction were also observed when the starter yeast was propagated under agitation in liquid medium containing pectin. CONCLUSIONS: Isolates capable of secreting pectinolytic activity on plates were predominant at the end of the citrus molasses fermentation. Nevertheless, the sizes of the secretion haloes on plates were not necessarily an indication of the levels of pectinolytic activity secreted in the liquid medium. SIGNIFICANCE AND IMPACT OF THE STUDY: Improved pectinolytic strains of Saccharomyces can be used as a source of pectinases for a variety of applications. This organism also participates in plant deterioration processes.     

Antifungal activity of propolis extract against yeasts isolated from onychomycosis lesions

The aim of this study was to determine the in vitro activity of propolis extract against 67 yeasts isolated from onychomycosis in patients attending at the Teaching and Research Laboratory of Clinical Analysis of the State University of Maringá. The method used was an adaptation made from the protocol approved by the National Committee for Clinical Laboratory Standards. The yeasts tested were: Candida parapsilosis 35%, C. tropicalis 23%, C. albicans 13%, and other species 29%. The propolis extract showed excellent performance regarding its antifungal activity: the concentration capable of inhibiting the all of the yeasts was 5 x 10(-2) mg/ml of flavonoids and 2 x 10(-2) mg/ml of flavonoids stimulated their cellular death. Trichosporon sp. were the most sensitive species, showing MIC50 and MIC90 of 1.25 x 10(-2) mg/ml of flavonoids, and C. tropicalis was the most resistant, with CFM50 of 5 x 10(-2) mg/ml of flavonoids and MFC90 of 10 x 10(-2) mg/ml. In view of the fact that propolis is a natural, low cost, nontoxic product with proven antifungal activity, it should be considered as another option in the onychomycosis treatment.     

Molecular identification and characterization of wine yeasts isolated from Tenerife (Canary Island, Spain)

AIMS: The present study was aimed at the identification, differentiation and characterization of indigenous yeasts isolated from Tenerife vineyards (viticulture region that has never been characterized before). Microbiota were studied from 14 samples taken during fermentations carried out in the 2002 vintage, from 11 wineries belonging to five wine regions on Tenerife Island. METHODS AND RESULTS: Yeasts' strains were identified and characterized through restriction analysis of the 5.8S-internal transcribed spacer region and the mitochondrial DNA. At the beginning of alcoholic fermentation, 26 yeast species were found, where 14 species were present in significant frequencies in only one sample. Likewise, the Saccharomyces cerevisiae strains isolated are very specific, as they were only present in one wine region. CONCLUSIONS: There were isolated specific yeasts from each region on Tenerife Island. The founded yeasts may be responsible for distinctive and interesting properties of the studied wines. SIGNIFICANCE AND IMPACT OF THE STUDY: This study forms part of an extensive taxonomic survey within the ecological framework of vineyards in Tenerife. This investigation is an essential step towards the preservation and exploitation of the hidden oenological potential of the untapped wealth of yeast biodiversity in the grape growing regions of this island. The results obtained demonstrate the value of using molecular genetic methods in taxonomic and ecological surveys. The results also shed some light on the ecology and oenological potential of S. cerevisiae strains isolated from this unique environment.     

The wine yeasts of the Cape

Summary The claims made byCusters in connection with the disproportionate yields of ethanol and carbon dioxide from the fermentative dissimilation of glucose in yeast water byBrett. claussenii were investigated forBrett. intermedius. All results obtained showed thatBrett. intermedius produced the normal equimolar amounts of ethanol and carbon dioxide, irrespective of whether the studies were conducted in yeast water or in dilute yeast water supplemented with a suitable nitrogen source. Re-investigation of the fermentative dissimilation of glucose in yeast water byBrett. claussenii gave the same results as withBrett. intermedius. Part I and II: Antonie van Leeuwenhoek24, 239, 1958;25, 145, 1959.     

The wine yeasts of the Cape

Summary Ascospore formation has been observed in three species of the genusBrettanomyces, viz. Brett. bruxellensis. Brett, intermedius andBrett. schanderlii. On media of adequate vitamin content these species form 1–4 hat-shaped ascospores. The spores are liberated rather soon after maturation. Heat treatment of ascogenous cultures indicated that these species are homothallic. In view of the fact that ascospore formation has been observed in the type species,Brett. bruxellensis, the transfer of the genus to theEndomycetaceae should be considered. Part I, II and III: Antonie van Leeuwenhoek 24, 239, 1958;25, 145, 1959;25, 449, 1959.