2.1 Materials
Ethylene glycol (EG), 1,3-propylene glycol (1,3-PG), 1,4-butylene glycol
(1,4-BG), 1,5-pentylene glycol (1,5-PG) and 1,6-hexylene glycol (1,6-HG)
were obtained from Aladdin Chemical Reagent Corporation. Yeast Extract
was purchased from Sigma-Aldrich. Sorbitol, MgSO4,
KH2PO4,
K2HPO4,
(NH4)2SO4 and CaCO3 were
obtained from Sinopharm Chemical Reagent Co., Ltd. (China). All other
chemicals were of analytical grade and were commercially available.