A respiration substrate-less isolation method for acute toxicity assessment

Respiration substrate (RS)-less isolation method was developed for enhancing the sensitivity of acute toxicity assessment of heavy metal ions. RS was removed from the first step of previous isolation method, which was an effective strategy for improving acute toxicity assessment. 50% inhibiting concentration (IC50) values of Cu2+, Cd2+, Zn2+, Hg2+ and Ni2+ were 0.39 mg L−1, 5.99 mg L−1, 3.99 mg L−1, 0.23 mg L−1 and 5.74 mg L−1, respectively. Beyond that, the complicacy of organic toxicants assessments was investigated by choosing 3,5-dichlorophenol (DCP) as model toxicant. Biofilm sensor, morphology method and suspended microbes-based methods including one-pot method, RS-isolation method, RS-less isolation method, RS-less isolation method with added potassium ferricyanide (+F), were compared. The sensitivity to DCP can be ranked as morphology method > suspended microbes-based methods > biofilm method. The difference of the present results implicated that the methodological interference, leading in different detection mechanisms of these methods. The relative investigations can provide theoretical guidance for developing comprehensive detection methods of pollutants. [Display omitted] •RS-less isolation method for acute toxicity assay was developed.•A significant enhancement of sensitivity for heavy metal ions was obtained.•A no significant enhancement of sensitivity for organic toxicants was obtained.•The methodologies of organic toxicant assessments was analyzed.•Organic toxicants have more easily affected by difference methodologies’ mechanisms.