Abstract: In July 2021, a severe flood occurred in some area of Henan Province, pig farms in these areas suffered heavy losses. The purpose of the current research is to explore the bacteria in the flood-affected water samples of pig farms, so as to provide technical support for the prevention and control of possible diseases. Different types of water samples including 19 drinking water, 22 rainwater, and 7 waste sewage samples were collected by field sampling and airmail from 26 farms in the affected areas. Using colony counting and high-throughput sequencing technology, the total number and the abundance of bacteria in the collected samples were analyzed, and disinfection tests were carried out for the collected water samples. The results showed that the total bacterial counts in drinking water, rainwater and sewage were 1.55×10⁵, 1.88×10⁸and 3.70×10⁹ CFU·mL^-1, respectively. The total number of bacteria in the sewage was the highest, followed by the rainwater, and that of the drinking water was the lowest, but still higher than the national standard of drinking water. By mean of high-throughput detection technology, potential pathogenic genus such as Streptococcus, Escherichia, Arcobacter, Actinobacter and Pseudomonas, as well as waterborne pathogenic bacteria such as Arcobacter cryaerophilus, Streptococcus suis, Escherichia coli, Acinetobacter baumannii and Aeromonas caviae, were detected in water samples. Bactericidal tests showed that when the final concentration of chlorine reaches 2 500 mg·L^-1, all bacteria in rainwater and sewage were killed within 30 minutes. It was demonstrated that water samples in pig farms after floods contained a variety of pathogenic bacteria and pig farms can choose chlorine-containing disinfectants to kill the bacteria in polluted water in the farm to ensure the health of humans and pigs.

Key words: 16S rDNA, pig farm, flood, bacteria