- Created one of the best strains for producing hydrogen from
bacteria
(Microb.
Biotechnol.,
1: 30-39 2008)
- Discovered cell signals are promiscuous in that indole from the
amino acid tryptophan impacts biofilms of cells that cannot
synthesize it (BMC
Microbiology 7:42 2007)
- Discovered hydroxy indoles are cell signals that control biofilm
formation of pathogenic E. coli and showed that indole is a
quorum-sensing signal
(Appl.
Environ. Microbiol.,
73: 4100-4109 2007)
- Found the X-ray crystallography structure of the first biofilm
protein, YmgB (renamed AriR) with collaborator Wolfgang Peti (J. Mol. Biol. 373:11-26,
2007)
- Discovered that stress increases biofilm formation and this
effect is mediated by YcfR (renamed to BhsA) in E. coli (J.
Bacteriol. 189: 3051-3062 2007)
- Determined for the first time what genes are expressed in the
rhizosphere for both a plant and a bacterial pathogen and discovered
seven new virulence factors (Microb.
Biotechnol. 1: 17-29 2008)
-
Discovered that the cell signal AI-2
increases biofilms in E. coli
(first report of AI-2 controlling a non-luminescence
phenotype) and found the uncharacterized protein MqsR mediates this
effect (J.
Bacteriol.
188: 305-316 2006)
- Discovered the protein that exports AI-2 from E. coli,
YdgG (renamed to TqsA) (J.
Bacteriol.
188:
587-598 2006)
-
Identified some of the genes
responsible for biofilm formation in E. coli and B. subtilis via
DNA microarrays
-
Pieced together a novel
metabolic pathway involving 8 genes for enhanced degradation of
trichloroethylene and cis-DCE by cloning a DNA-shuffled toluene o-monooxygenase
(that initiates attack on the chlorinated aliphatic), a novel glutathione S-transferase
(to remove the toxic epoxide formed by the monooxygenase), and g-glutamylcysteine
synthetase (that provides to cofactor glutathione for the glutathione S-transferase)
-
Identified the key amino
acids responsible indole oxidation and color formation (e.g., indigo,
indirubin, isoindigo, isatin) via toluene o-monooxygenase of B.
cepacia G4 as well as the key amino acids responsible regiospecific
hydroxylation of toluene by toluene m-monooxygenase of R. pickettii;
hence, monooxygenases have been constructed which are designed for specific,
active, whole-cell biocatalysis
-
Discovered aromatic
monooxygenases such as T3MO of R. pickettii and T4MO of P. mendocina
KR1 catalyze three successive hydroxylations to convert benzene to
trihydroxybenzene, opening the possibility of using these strains to form
important dihydroxy and trihydroxy compounds
-
Evolved (using DNA shuffling
and saturation mutagenesis) the family of aromatic monooxygenases (ToMO of
P. stutzeri OX1, TOM of B. cepacia G4, T3MO of R. pickettii,
& T4MO of P. mendocina KR1) to produce industrially-significant
compounds such as methyl dihydroxy aromatics (e.g., 4-methylresorcinol,
methylhydroquinone, pyrogallol), methoxy dihydroxy aromatics
(3-methoxycatechol, methoxyhydroquinone), and nitro dihydroxy aromatics
(4-nitrocatechol)
-
Determined via DNA
microarrays that furanone, the anti-biofilm compound from the seaweed
Delisea pulchra that does not affect the growth of Gram-negative strains,
inhibits AI-2 quorum sensing in Gram-negative strains
-
Elucidated the genetic basis
of the inhibition of Gram-positive strains by furanone from the seaweed
Delisea pulchra; this compound may have importance as a novel
antimicrobial
-
Found that furanone from the
seaweed Delisea pulchra both stimulates and inhibits siderophore
formation in pseudomonads and that it may be used to decrease corrosion
-
Discovered Pseudomonas
stutzeri OX1 is chemotactic toward chlorinated compounds (e.g., TCE, PCE,
cis-DCE, trans-DCE, 1,1-DCE, vinyl chloride) so this one strain
moves toward PCE, PCE induces ToMO formation, then ToMO degrades PCE
-
Found that biofilms that
produce the peptide antimicrobial gramicidin S may be used to inhibit the
corrosion causing bacteria Leptothrix discophora SP-6 and
Desulfosporosinus orientis), and that this biofilm is active in process
water from the Three Mile Island nuclear facility
-
Evolved the aromatic
monooxygenase toluene o-monooxygenase (TOM) from Burkholderia
cepacia G4 for the synthesis of 1-naphthol from naphthalene and for the
degradation of chlorinated ethenes (Journal
of Bacteriology 184: 344-349, 2002), then used saturation mutagenesis
to improve chloroform degradation
-
Evolved bacterial
dinitrotoluene dioxygenases for the bioremediation of nitroaromatics and green
chemical synthesis (using the combinatorial method of directed evolution, with
Prof. Barth Smets)
-
Expressing bacterial
dioxygenases for the bioremediation of nitroaromatics and green chemical
synthesis (using the combinatorial method of directed evolution, with Prof.
Barth Smets)
-
Showed that furanone from
the seaweed Delisea pulchra inhibits both known autoinducers for
bacterial cell communication (Environmental
Microbiology 3:731-736, 2001)
-
Discovered the first
bacterium, Pseudomonas stutzeri OX1, capable of degrading aerobically
one of the world's most serious pollutants, tetrachloroethylene (Nature
Biotechnology 18: 775-778, 2000)
-
Created the first
tree-colonizing bacteria for bioremediation (competitve TCE-degrading bacteria
for use with poplar trees,
Applied & Environmental Microbiology 66: 4673-4678, 2000)
-
Discovered toluene/o-xylene
monooxygenase from Pseudomonas stutzeri can degrade chlorinated
aliphatics as well as mixtures of chlorinated aliphatics (including
tetrachloroethylene,
Applied & Environmental Microbiology 64: 3023-3024, 1998)
-
Created the first
rhizoremediation system using a genetically-engineered bacterium and plant
root for the degradation of trichloroethylene (Applied
& Environmental Microbiology 64: 112-118, 1998)
-
Achieved expression in a
recombinant host for the first time of soluble methane monooxygenase from
Methylosinus trichosporium OB3b and used it to degrade TCE and chloroform
without inducers and without competitive inhibition
(Applied & Environmental Microbiology 60:
2473-2482, 1994)
-
Quantified the ability of
the hok locus of the E. coli R1 plasmid to stabilize plasmids
(200 generations) and introduced the idea of using multiple loci for
increasing plasmid stability (Applied
& Environmental Microbiology 63: 1917-1924, 1997)
-
Determined the likely
evolutionary importance of the Hok killer gene: it allows cells to commit
suicide to prevent the propagation of phage such as T4 (one of only several
wild-type altruistic genes,
Journal of Bacteriology 178: 2044-2050, 1997)
-
Developed one of the first
two-stage systems for the destruction of pollutants: treat first with a
general physical technique (energetic electrons from pulsed-electric
discharge) and then complete the degradation with bacteria (used this
technique to degrade perchloroethylene and chlorinated phenols in a fixed-film
fluidized-bed bioreactor)
-
Showed biofilms can decrease
corrosion on mild steel (by 40-fold), stainless steel, copper, brass, and
aluminum
-
Developed one of the first
genetically-engineered biofilms and used it to secrete successfully
antimicrobials that inhibit the growth of deleterious sulfate-reducing
bacteria (SRB); used this biofilm to reduce the corrosion by inhibiting the
growth of SRB
-
Quantified TCE degradation
in the first fixed-film bioreactor that uses genetically-engineered bacteria
to degrade TCE for an appreciable period (developed a mathematical model for
the biofilm reactor)
-
Enhanced expression of
lignin peroxidase from Streptomyces viridosporus by formulating a novel
corn-starch-based medium
-
Discerned that the
translational machinery of the E. coli cell limits recombinant protein
production (for high gene dosage and strong promoters) and used specialized
ribosomes to enhance productivity
