MICROBIAL ECOPHYSIOLOGY  PROJECTS

Olivine bioweathering and signatures of life on Mars

Olivine (popular name: peridot) is a mineral from volcanic rocks.  Microscopic analysis of thin sections of olivine crystals revealed microchannels (0.5-10 microns in diameter).  Such features were also seen in three billion years old rocks and in the Martian meteorite Nakhla.  It is already known that olivine weathering can be produced by abiotic processes as well.  The question is: can microchannels also be produced by living cells?  We study microbial activity on olivine surfaces.  This includes: isolation and identification of microbes, measuring changes in physiology in the presence of olivine crystals and the signatures of this activity.  (Collaborators: Martin Fisk (OSU); Amy Smith; Wen Fang). 

Extremophilic fungi communities grow by iron oxidation  

In 2000 (while at Caltech) Radu Popa discovered a community of extremophilic fungi.  They belong to a group of Ascomycetes called Fusarium and have the unique ability to grow in low nutrient media (virtually distilled water) in very acidic conditions (pH 0.8) when glass surfaces are present.  Similar to other related fungi these microbes also have the ability to facilitate redox reactions with inorganic iron.  We isolate strains from this community and study their physiology.  This work includes measuring respiration, resistance to antibiotics, and changes in growth rate and biochemical composition in response to nutrient availability.  (Collaborators: Eileen Fitzpatrick; Yelena Kiseleva; Dania Youssef). 

The microbial eco-physiology of wet cellulose composting 

Acid Fermentation of Cellulose (AFC) is a fast and environmentally friendly means to compost.  It helps sequester carbon in soil and reduces emission of Greenhouse Gases (GHG).  This biotechnology uses bacteria and yeasts to degrade cellulose-rich materials (such as grass, hay, straw, leaves, paper, mulch, wood chips, saw dust and food scraps).  The product is carbon- and energy-rich organic compost.  We study means to control the cellulose hydrolysis and to optimize its decomposition.  We isolate microbes and study environmentally friendly means to optimize AFC, including the detoxification of compost tea by bio-electrochemical oxidation.  (Collaborators: Terrence R. Green; Manar Alattar; Mikias Tizazzu).

PREBIOTIC  EVOLUTION  PROJECTS

The participation of H₂¹⁷O to chiral reactivity

The origin of prebiotic chirality is one of the biggest mysteries of the origin of life.  Though the value of chirality to the functioning of living cells is well understood, the mechanisms allowing chirality to occur in the prebiotic earth are obscure.  Classical physical-chemistry prohibits any significant changes in enantiomeric excess when life is absent.  We found significant differences in reactivity (proton exchange) between enantiomers, correlated with the concentration of H₂¹⁷O and pH.  We study proton exchange enantiodifferences and the organization of 3s-nuclear spin systems in H₂¹⁷O and –NH₂ groups by using Time Domain ¹H Nuclear Magnetic Resonance. (Collaborators: Romulus. I. Scorei; Vily M. Cimpoiasu (University of Craiova, Romania)).