Identification of Dekkera bruxellensis as a major contaminant yeast in continuous fuel ethanol fermentation

Abstract

Aims: To identify and characterize the main contaminant yeast species detected in fuel‐ethanol production plants in Northeast region of Brazil by using molecular methods. Methods and Results: Total DNA from yeast colonies isolated from the fermentation must of industrial alcohol plants was submitted to PCR fingerprinting, D1/D2 28S rDNA sequencing and species‐specific PCR analysis. The most frequent non‐Saccharomyces cerevisiae isolates were identified as belonging to the species Dekkera bruxellensis, and several genetic strains could be discriminated among the isolates. The yeast population dynamics was followed on a daily basis during a whole crop harvesting period in a particular industry, showing the potential of D. bruxellensis to grow faster than S. cerevisiae in industrial conditions, causing recurrent and severe contamination episodes. Conclusions: The results showed that D. bruxellensis is one of the most important contaminant yeasts in distilleries producing fuel‐ethanol from crude sugar cane juice, specially in continuous fermentation systems. Significance and Impact of the Study: Severe contamination of the industrial fermentation process by Dekkera yeasts has a negative impact on ethanol yield and productivity. Therefore, early detection of D. bruxellensis in industrial musts may avoid operational problems in alcohol‐producing plants.

Diversity in Spoilage Yeast Dekkera/Brettanomyces bruxellensis Isolated from French Red Wine. Assessment During Fermentation of Synthetic Wine Medium

“…4C). 35 has also shown intraspecific variability among industrial isolates contaminating one bio-ethanol plant. On the contrary, Mitrakul et al 26 suggested the predominance of a single strain on spoiled wines from several vintages produced in a California winery.…”

“…These faults cause large economic losses 13 . In the last fifteen years, studies regarding these microorganisms have multiplied in a significant way 3,6,7,20,31,35 and indicate a desire to understand the behaviour of Brettanomyces and to prevent or at least control its development in the winemaking process.…”

Effects of Oxygen Availability on Acetic Acid Tolerance and Intracellular pH in Dekkera bruxellensis

“…However, this yeast has been reported to contaminate distilleries that produce fuel ethanol, especially continuous fermentation systems, where it can compete with S. cerevisiae (13,14), due to its high ethanol and acidic tolerance. Recent studies have indicated that D. bruxellensis can use nitrate as a nitrogen source, and this characteristic is well suited for industrial fermentation (15,16). D. bruxellensis has been reported as being unable to use xylose, but several strains are able to metabolize cellobiose (17).…”

Lachancea mirantina sp. nov., an ascomycetous yeast isolated from the cachaça fermentation process

“…T was amplified using primers NL-1 (59-GCATATCAATAAGCGGAGGAAAAG-39) and NL-4 (59-GTCCGTGTTTCAAGACGG-39), according to de Souza Liberal et al (2007). The EFA1 gene was amplified using primers yEF1-for (59-GTAAGGGTTCTTTCAAGTACGC-39) and yEF1-rev (59-GGAGTCACCAAAGACGTTACC-39) designed from the conserved 59-terminal and 39-terminal regions of the Zygosaccharomyces gene deposited at the NCBI database (GenBank accession nos AF402076.1, AF402075.1, AF402059.1, AF402058.1 and AF402055.1).…”