[1] Food Res Inst Prague, Dept Chem Biochem & Food Microbiol, Prague 10, Czech Republic
[2] Univ Chem & Technol, Dept Biochem & Microbiol, Prague 6, Czech Republic
[3] Keele Univ, Lennard Jones Sch Chem & Phys Sci, Keele ST5 5BG, Staffs, England
[4] Charles Univ Prague, Inst Environm Studies, Fac Sci, Prague 2, Czech Republic