Effects of some human pathogenic bacteria and heavy metals on embriyological development of model organism zebrafish (Danio rerio)

Zebrafish (Danio rerio) is used as a model organism in scientific studies. For this reason, this study aimed to investigate the toxic effect of some heavy metals, which are FeClOH, K3Fe(CN)6, KCN, and CuSO4), and some human pathogenic bacteria, which are Methicillin-resistant Staphylococcus aureus (MRSA), methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-sensitive coagulase-negative Staphylococcus epidermidis (MSCoNS), Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli, on the embryological development of model organism zebrafish (Danio rerio). Zebrafish embryos were exposed to different heavy metals at a concentration was 0.5 mg/L for 96 hpf (hours post-fertilization). Mortality, hatching, and malformation rates were examined during the exposure period. The result showed that FeClOH and K3Fe(CN)6 were toxic to zebrafish embryos and caused an increased mortality rate of ≤ 50% and delayed hatching. Moreover, FeClOH and K3Fe(CN)6 caused a type of abnormalities while KCN and CuSO4 were more toxic to zebrafish embryos and caused a mortality rate increased, which was 100% at 24 hpf. On the other hand, when zebrafish embryos were infected with human pathogenic bacteria such as Methicillin-resistant Staphylococcus aureus (MRSA), Methicillin-Susceptible Staphylococcus aureus (MSSA), methicillin-sensitive coagulase-negative Staphylococcus epidermidis (MSCoNS), Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli, at 1 x 106 CFU/mL for 110 hpf mortality, hatching and malformation rates were examined. The results showed all of the human pathogenic bacteria caused an increased mortality rate of ≤ 50% and delay hatching. Some human pathogenic bacteria (methicillin-sensitive coagulase-negative Staphylococcus epidermidis (MSCoNS), Acinetobacter baumannii, and Escherichia coli) caused several types of abnormalities. In conclusion, short-term exposure to heavy metals and pathogenic bacteria has a toxic effect on zebrafish embryos' development.