D-Fructose Assimilation and Fermentation by Yeasts Belonging to Saccharomycetes: Rediscovery of Universal Phenotypes and Elucidation of Fructophilic Behaviors in Ambrosiozyma platypodis and Cyberlindnera americana

The purpose of this study was to investigate the ability of ascomycetous yeasts to assimilate/ferment d-fructose. This ability of the vast majority of yeasts has long been neglected since the standardization of the methodology around 1950, wherein fructose was excluded from the standard set of physiological properties for characterizing yeast species, despite the ubiquitous presence of fructose in the natural environment. In this study, we examined 388 strains of yeast, mainly belonging to the Saccharomycetes (Saccharomycotina, Ascomycota), to determine whether they can assimilate/ferment d-fructose. Conventional methods, using liquid medium containing yeast nitrogen base +0.5% (w/v) of d-fructose solution for assimilation and yeast extract-peptone +2% (w/v) fructose solution with an inverted Durham tube for fermentation, were used. All strains examined (n = 388, 100%) assimilated d-fructose, whereas 302 (77.8%) of them fermented d-fructose. In addition, almost all strains capable of fermenting d-glucose could also ferment d-fructose. These results strongly suggest that the ability to assimilate/ferment d-fructose is a universal phenotype among yeasts in the Saccharomycetes. Furthermore, the fructophilic behavior of Ambrosiozyma platypodis JCM 1843 and Cyberlindnera americana JCM 3592 was characterized by sugar consumption profiles during fermentation.

Production and characterisation of non-alcoholic beer using special yeast

Non-Saccharomyces yeast strains Saccharomycodes ludwigii, Schizosaccharomyces pombe, Lachancea fermentati and Pichia angusta together with a hybrid yeast strain cross-bred between genetically modified Saccharomyces cerevisiae W303-1A G418R and Saccharomyces eubayanus as well as the parent yeasts of the hybrid were studied for potential use for non-alcoholic beer production. The hybrid yeast, its Saccharomyces cerevisiae W303-1A G418R parent and Saccharomycodes ludwigii were not able to metabolise maltose during Durham tube tests. Schizosaccharomyces pombe, Lachancea fermentati and Pichia angusta metabolised maltose, however, showed limited ethanol production. Parameters, volatile and non-volatile organic compounds of beers produced by the studied yeast were analysed and compared to a beer produced by bottom fermented brewer’s yeast Saccharomyces pastorianus.

Isolation and characterization of Acetobacter aceti from rotten papaya

The present study was concerned with the isolation and characterization of Acetobacter aceti from rotten papaya for vinegar production. The samples were inoculated in sterilized GYC standard media and then incubated at 30°C for 48 hours. Successive subculture was performed to screen out the strains. In Gram’s staining, the morphology of the isolated bacteria exhibited pink, small rod shaped single, pair and chain in arrangement, in the hanging drops technique, all the isolates revealed motile. Biochemical tests were performed by fermentation of five basic sugars by producing both acid and gas bubbles in Durham tube. All of the isolates were Indole, Voges-Proskauer (VP) and Oxidase negative, Methyl Red (MR) and Catalase positive. The growth rate of isolated strain was optimized by weighing dry cell and turbidity at 600 nm at different concentrations of dextrose (1%, 5% and 10%). Ten (10) percent dextrose solution showed rapid growth and higher cell mass than 5% and 1% solution respectively. Acidity of the media gradually increased from 0.102% to 2.18% from day 0 to day 7 and pH of the media decreased from 6.8 to 5.5 during the period. This protocol was successful for enriching Acetobacter aceti, which was essential for vinegar production.J. Bangladesh Agril. Univ. 13(2): 299-306, December 2015

KONTAMINASI BAKTERI KOLIFORM PADA AIR MINUM ISI ULANG DI DESA ILIE KECAMATAN ULEE KARENG KOTA BANDA ACEH (Contamination of Coliform in Refill Water in Ilie Village, Ulee Kareng, Banda Aceh)

The purpose of this study was to find out whether the refill water (AMIU) was contaminated with coliform or not. The methods used were presumptive, confirmed, and completed test. Sample of this study was refill water (AMIU) from five refill water shops located in Ilie village, sub-district of Ulee Kareng, Banda Aceh. The sample was taken 3 times with interval period of one week. Sample was culture in lactose broth and incubated at 37° C for 48 hours. If it did not form gas in Durham tube, presumptive test result was considered negative and the samples were not proceed to the other test. The data was presented using descriptive analysis. It could be concluded that AMIU from 5 shops in Ilie Ulee Kareng, Banda Aceh is negatively contaminated with coliform bacteria.

A FERMENTATION TUBE AND MEDIUM FOR FASTIDIOUS ANAEROBES

A modified fermentation tube was devised by introducing a glass rod in the small inverted Durham tube to keep its mouth away from the bottom of the outer main tube, thus providing the maximum opportunity for gas collection. A medium containing autoclavable growth factors was developed, which, when added to the main tubes with a few particles of cooked meat, allowed growth of fastidious anaerobes. Each ingredient was shown to be free of any fermentable substance that might lead to gas formation. The fermentation tubes were incubated in an anaerobic jar.