Department of Biochemistry, Microbiology and Molecular Biology, University of Maine, Orono, ME 04469-5735, USA.|Department of Biochemistry, Microbiology and Molecular Biology, University of Maine, Orono, ME 04469-5735, USA.|Department of Biochemistry, Microbiology and Molecular Biology, University of Maine, Orono, ME 04469-5735, USA.|Department of Biochemistry, Microbiology and Molecular Biology, University of Maine, Orono, ME 04469-5735, USA.|Department of Biochemistry, Microbiology and Molecular Biology, University of Maine, Orono, ME 04469-5735, USA.|Department of Biochemistry, Microbiology and Molecular Biology, University of Maine, Orono, ME 04469-5735, USA.|Department of Biochemistry, Microbiology and Molecular Biology, University of Maine, Orono, ME 04469-5735, USA.|Department of Biochemistry, Microbiology and Molecular Biology, University of Maine, Orono, ME 04469-5735, USA.