Project 5
Screening of Inorganic Fungicides Against the Skin Ulceration Disease of Stichopus japonicus¶
Jul. 2018 – May 2019
In this research, we focused on investigating the impact of heavy metal ions on pathogenic bacteria responsible for causing skin ulceration disease in Stichopus japonicus. We specifically targeted commonly used inorganic compounds containing copper, zinc, and selenium. By analyzing the growth characteristics of these bacteria in solutions with varying concentrations of these heavy metal ions, as well as their combined concentrations, we aimed to identify the optimal composition and concentrations of drug components for effectively inhibiting bacterial growth.
To begin, we employed techniques such as plate coating and scribing separation to purify the bacterial strains. During the initial experimentation phase, we cultured these strains in the presence of varying concentrations of copper, zinc, and selenium ions. The objective was to ascertain the minimum inhibitory concentration of each ion against the pathogenic bacteria. The results revealed that the minimum inhibitory concentration for zinc ions was 185 mg/L, while for copper ions, it was 58 mg/L. Interestingly, selenium ions exhibited limited bactericidal efficacy even at high concentrations.
Consequently, we proceeded to establish a gradient range spanning from 0 to 185 mg/L. Within this range, we organized eight experimental groups alongside a control group. Our analysis encompassed evaluating indicators such as fresh weight, absorbance, and colony count following the bacterial culture. Notably, our findings indicated that copper and selenium ions displayed a stimulatory effect at lower concentrations. This effect, however, was less pronounced in the presence of zinc ions. On the other hand, both copper and selenium ions demonstrated an inhibitory effect at higher concentrations. Additionally, zinc ions exhibited inhibitory properties, albeit this inhibition was counteracted by the stimulatory influence of copper and selenium ions.
