Individual and Combined Toxicity of Antibacterial Substances to Green Alga Pseudokirchneriella subcapitata

Acute toxicity tests were carried out to obtain EC50 for ten types of antibiotic substances, i.e., cefazolin, oxytetracycline, doxycyclin hyclate, amoxicillin, tylosin, lincomycin HCl, oxolinic acid, sulfamonomethoxin, enrofloxacine, and trimethoprim, for the green alga Pseudokirchneriella subcapitata. Through a comparison of EC50 obtained in this study with that for a variety of species, the relationships between action mechanisms of the antibiotic substances and growth inhibitions of P. subcapitata were discussed. Then, another acute toxicity test was performed to assess the growth inhibition when using the mixtures of enrofloxacine and sulfamonomethoxin or enrofloxacine and lincomycin at certain specific mixing ratios that had been determined to be Toxic Unit (TU) mixing ratios. The results indicated that the toxicities of both mixtures to P. subcapitata were shown to be an additive effect.