The culture flasks were incubated on a rotary shaker at 120 rpm, 23 ± 1◦C and20 mol m−2s−1in a 8/16 h light:dark photo-period for 28 days.Later suspension cultures were established by filtering the initial suspension through 47-m pore size sterile filters to remove largercell clumps. About 10 ml of the filtrate was subcultured repeatedlyin 250-ml Erlenmeyer flasks containing 150 ml medium of the samecomposition