Flocculation phenomenon of a mutant flocculent Saccharomyces cerevisiae strain: Effects of metal ions, sugars, temperature, pH, protein-denaturants and enzyme treatments

Abstract

The flocculation mechanism of a stable mutant flocculent yeast strain Saccharomyces cerevisiae KRM-1 was quantitatively investigated for potential industrial interest. It was found that the mutant flocculent strain was NewFlo phenotype by means of sugar inhibition test. The flocculation was completely inhibited by treatment with proteinase K, protein-denaturants and carbohydrate modifier. The absence of calcium ions significantly inhibited the flocculation, indicating that Ca 2+ was specifically required for flocculation. The flocculation was stable when temperature below 70°C and pH was in the range of 3.0-6.0. The flocculation onset of the mutant flocculent strain was in the early stationary growth phase, which coincided with glucose depletion in the batch fermentation for the production of ethanol from kitchen refuse medium. The results are expected to help develop better strategies for the control of mutant flocculent yeast for future large-scale industrial ethanol fermentation.

Pengaruh penambahan daun pandan terhadap mutu sirup nira aren

“…Pengolahan sirup nira aren ini tidak dilakukan penambahan gula pasir, sehingga sakarosa yang terkandung adalah alami hanya dari nira aren dan dengan adanya senyawa fenolat, maka sirup nira aren dapat dikategorikan sebagai nira aren fungsional (Rindengan et al, 2020) Rasa yang masih tetap disukai walaupun telah disimpan selama 45 hari mungkin karena menurut Ma et al (2010) menyatakan bahwa suhu merupakan faktor penting yang dapat mempengaruhi pertumbuhan dan metabolisme khamir. Dengan pemanasan nira menjadi sirup akan mengurangi proses kerusakan nira.…”

Nano-ZnO Induced Flocculation of <i>Saccharomyces cerevisiae</i>

“…In many cases however, the yeast strains used in industrial fermentations fail to live up to latter phase which flocculated early leading to premature flocculation . Meanwhile, the self-flocculation is a very strain-specific phenomenon which is affected by numerous parameters such as nutrient conditions, dissolved oxygen, pH and fermentation temperature, making it difficult to predict specific responses [6,7]. In addition, certain genes involved in self-flocculation are extremely variable, causing frequent changes in the flocculation profile of some strains.…”