EBI Personnel Directory Miller, Michael

Biofuels Production

Michael Miller





Yeast produced endolysins to prevent bacterial infections of ethanol fermentation

Generally, fuel ethanol fermentations are not designed to be carried out under pure culture conditions and are prone to bacterial infections, typically by lactobacilli. Bacterial infections decrease the profitability of ethanol production by decreasing ethanol yield. In extreme cases, bacterial infections can lead to a "stuck" fermentation (little or no conversion of sugar into ethanol) which results in plant closures for cleaning. To combat bacterial infections, ethanol producers could use antibiotics. Unfortunately, the use of antibiotics has three significant negatives: I) cost of antibiotics; 2) limited long-term usefulness due to antibiotic resistance; and 3) strengthening lack of support for use of antibiotics in agriculture. In fact, concern over the development of antibiotic resistance in ethanol fermentations has led to a ban of antibiotic use in Europe and pressure is mounting for a similar ban in the United States. Our goal is to develop an inexpensive and effective alternative to antibiotics in fuel ethanol fermentations.


Engineering Phage Resistance in Solventogenic Clostridia Using CRISPR/Cas

Bacteriophages, viruses that infect bacteria, have the potential to interfere with any industrial process that relies on bacterial fermentation including the acetone-butanol-ethanol (ABE) fermentation with solventogenic clostridia. During the history of the ABE fermentation, there have been several documented bacteriophage (phage) infections resulting in dramatically reduced yields. It is prudent to expect that phage infections will continue with the redevelopment of the ABE fermentation industry. The traditional method to deal with phage infections is to isolate bacteriophage insensitive mutants (BIMs) using a process termed "immunization." However, this strategy is not ideal because it 1) only treats the current phage infection; 2) takes a minimum of 2 weeks; and 3) often results in BIMs with reduced fermentation characteristics compared to the parental strain. To insure the profitability of the ABE industry, it is necessary to develop an economical solution to phage infections.