Phenotypic characterization and comparative transcriptomics of evolved Saccharomyces cerevisiae strains with improved tolerance to lignocellulosic derived inhibitors.

Background: Lignocellulosic biomass continues to be investigated as a viable source for bioethanol production. However, the pretreatment process generates inhibitory compounds that impair the growth and fermentation performance of microorganisms such as Saccharomyces cerevisiae. Pinewood specifically has been shown to be challenging in obtaining industrially relevant ethanol titers.

Transformation and electrophoretic karyotyping of Coniochaeta ligniaria NRRL30616.

Coniochaeta ligniaria NRRL30616 is an ascomycete that grows with yeast-like appearance in liquid culture. The strain has potential utility for conversion of fibrous biomass to fuels or chemicals. Furans and other inhibitory compounds in lignocellulosic biomass are metabolized by NRRL30616, facilitating subsequent microbial fermentation of biomass sugars.

Furfural induces reactive oxygen species accumulation and cellular damage in Saccharomyces cerevisiae.

Background: Biofuels offer a viable alternative to petroleum-based fuel. However, current methods are not sufficient and the technology required in order to use lignocellulosic biomass as a fermentation substrate faces several challenges. One challenge is the need for a robust fermentative microorganism that can tolerate the inhibitors present during lignocellulosic fermentation.

Culture nutrition and physiology impact the inhibitor tolerance of the yeast Pichia stipitis NRRL Y-7124.

Pichia stipitis NRRL Y-7124 is one of the natural yeasts best able to utilize biomass because it is able to ferment hexoses and the pentose, xylose, to economically recoverable concentrations of ethanol. To test the impact of culture conditions on inhibitor tolerance, inhibitors were spiked to growing or stationary-phase P. stipitis supplied either glucose or xylose and varying nitrogen and mineral compositions; then the ensuing specific death rate response was measured.

Nitrogen source and mineral optimization enhance D: -xylose conversion to ethanol by the yeast Pichia stipitis NRRL Y-7124.

Nutrition-based strategies to optimize xylose to ethanol conversion by Pichia stipitis were identified in growing and stationary-phase cultures provided with a defined medium varied in nitrogen, vitamin, purine/pyrimidine, and mineral content via full or partial factorial designs. It is surprising to note that stationary-phase cultures were unable to ferment xylose (or glucose) to ethanol without the addition of a nitrogen source, such as amino acids. Ethanol accumulation increased with arginine, alanine, aspartic acid, glutamic acid, glycine, histidine, leucine, and tyrosine, but declined with isoleucine.

Importance of mitochondrial dynamics during meiosis and sporulation.

Opposing fission and fusion events maintain the yeast mitochondrial network. Six proteins regulate these membrane dynamics during mitotic growth-Dnm1p, Mdv1p, and Fis1p mediate fission; Fzo1p, Mgm1p, and Ugo1p mediate fusion. Previous studies established that mitochondria fragment and rejoin at distinct stages during meiosis and sporulation, suggesting that mitochondrial fission and fusion are required during this process.

Mitochondrial GFA2 is required for synergid cell death in Arabidopsis.

Little is known about the molecular processes that govern female gametophyte (FG) development and function, and few FG-expressed genes have been identified. We report the identification and phenotypic analysis of 31 new FG mutants in Arabidopsis. These mutants have defects throughout development, indicating that FG-expressed genes govern essentially every step of FG development.