Diversity of lactic acid bacteria of the bioethanol process

BackgroundBacteria may compete with yeast for nutrients during bioethanol production process, potentially causing economic losses. This is the first study aiming at the quantification and identification of Lactic Acid Bacteria (LAB) present in the bioethanol industrial processes in different distilleries of Brazil.ResultsA total of 489 LAB isolates were obtained from four distilleries in 2007 and 2008. The abundance of LAB in the fermentation tanks varied between 6.0 × 105 and 8.9 × 108 CFUs/mL. Crude sugar cane juice contained 7.4 × 107 to 6.0 × 108 LAB CFUs. Most of the LAB isolates belonged to the genus Lactobacillus according to rRNA operon enzyme restriction profiles. A variety of Lactobacillus species occurred throughout the bioethanol process, but the most frequently found species towards the end of the harvest season were L. fermentum and L. vini. The different rep-PCR patterns indicate the co-occurrence of distinct populations of the species L. fermentum and L. vini, suggesting a great intraspecific diversity. Representative isolates of both species had the ability to grow in medium containing up to 10% ethanol, suggesting selection of ethanol tolerant bacteria throughout the process.ConclusionsThis study served as a first survey of the LAB diversity in the bioethanol process in Brazil. The abundance and diversity of LAB suggest that they have a significant impact in the bioethanol process.

[1]  H. Amorim,et al.  Fermentação alcoólica: ciência e tecnologia , 2005 .

[2]  N. Narendranath,et al.  Relationship between pH and Medium Dissolved Solids in Terms of Growth and Metabolism of Lactobacilli and Saccharomyces cerevisiae during Ethanol Production , 2005, Applied and Environmental Microbiology.

[3]  D. A. Tuan,et al.  Microbial diversity of traditional Vietnamese alcohol fermentation starters (banh men) as determined by PCR-mediated DGGE. , 2008, International journal of food microbiology.

[4]  R. Grappin,et al.  Origin and diversity of mesophilic lactobacilli in Comté cheese, as revealed by PCR with repetitive and species-specific primers , 2001 .

[5]  D. Lane.  16S/23S rRNA sequencing , 1991 .

[6]  M. A. de Morais Jr,et al.  Isolation by genetic and physiological characteristics of a fuel-ethanol fermentative Saccharomyces cerevisiae strain with potential for genetic manipulation , 2005, Journal of Industrial Microbiology and Biotechnology.

[7]  J. De Morais,et al.  Identification of Dekkera bruxellensis as a major contaminant yeast in continuous fuel ethanol fermentation , 2007, Journal of applied microbiology.

[8]  W. M. Ingledew,et al.  Effects of lactobacilli on yeast-catalyzed ethanol fermentations , 1997, Applied and environmental microbiology.

[9]  M. Rogosa,et al.  A MEDIUM FOR THE CULTIVATION OF LACTOBACILLI , 1960 .

[10]  R. E. Lumpkin,et al.  Contaminant occurrence, identification and control in a pilot-scale corn fiber to ethanol conversion process. , 2007, Bioresource technology.

[11]  J. Lupski,et al.  Genomic fingerprinting of bacteria using repetitive sequence-based polymerase chain reaction , 1994 .

[12]  D. Angelis,et al.  Quantificação da floculação de Saccharomyces cerevisiae por bactérias contaminantes da fermentação alcoólica , 2001 .

[13]  R. Aznar,et al.  Lactobacillus vini sp. nov., a wine lactic acid bacterium homofermentative for pentoses. , 2006, International journal of systematic and evolutionary microbiology.

[14]  E. Stackebrandt,et al.  Nucleic acid techniques in bacterial systematics , 1991 .

[15]  W. M. Ingledew,et al.  Acetic Acid and Lactic Acid Inhibition of Growth of Saccharomyces Cerevisiae by Different Mechanisms , 2001 .

[16]  D. Gevers,et al.  Identification of lactobacilli by pheS and rpoA gene sequence analyses. , 2007, International journal of systematic and evolutionary microbiology.

[17]  W. M. Ingledew,et al.  Effect of lactic acid bacteria on wheat mash fermentations prepared with laboratory backset , 1994 .

[18]  T. Leathers,et al.  Bacterial contaminants of fuel ethanol production , 2004, Journal of Industrial Microbiology and Biotechnology.

[19]  J. De Morais,et al.  Yeast population dynamics of industrial fuel-ethanol fermentation process assessed by PCR-fingerprinting , 2005, Antonie van Leeuwenhoek.

[20]  A. Tilsala-Timisjärvi,et al.  Development of oligonucleotide primers from the 16S-23S rRNA intergenic sequences for identifying different dairy and probiotic lactic acid bacteria by PCR. , 1997, International journal of food microbiology.

[21]  J. Nicoli,et al.  Identification to the species level of Lactobacillus isolated in probiotic prospecting studies of human, animal or food origin by 16S-23S rRNA restriction profiling , 2005, BMC Microbiology.

[22]  J. Schnürer,et al.  Dekkera bruxellensis and Lactobacillus vini Form a Stable Ethanol-Producing Consortium in a Commercial Alcohol Production Process , 2007, Applied and Environmental Microbiology.

[23]  M. L. Lopes,et al.  Yeast selection for fuel ethanol production in Brazil. , 2008, FEMS yeast research.

[24]  J. Horii,et al.  Viabilidade celular de Saccharomyces cerevisiae cultivada em associação com bactérias contaminantes da fermentação alcoólica Cellular viability of Saccharomyces cerevisiae cultivated in association with contaminant bacteria of alcoholic fermentation , 2007 .

[25]  D. A. Abbott,et al.  Growth rates of Dekkera/Brettanomyces yeasts hinder their ability to compete with Saccharomyces cerevisiae in batch corn mash fermentations , 2005, Applied Microbiology and Biotechnology.

[26]  P. Oliva-Neto,et al.  Caracteristicas da floculacao de leveduras por lactobacillus fermentum , 1991 .

[27]  P. R. de Araujo,et al.  Detection and Identification of Wild Yeast Contaminants of the Industrial Fuel Ethanol Fermentation Process , 2008, Current Microbiology.