Phylogenetic diversity and relationship between of sediment, water and fish bacterial in Karoon River (case study: Ahvaz City)

Abstract

Introduction: Bacteria are the most abundant and richest group of organisms that play a
vital role in many important ecosystem processes; hence their diversity has been investigated
in various studies. This research was conducted with the aim of investigating the
phylogenetic diversity of bacteria in the Karoon River and its relationship with sediment and
fish.
Materials & Methods: This study was conducted in the spring of 2022 and on the bacteria
of water samples, sediment and Cyprinus carpio, Tilapia zilli and Barbus barbulus of 4
stations of the Karoon River in Ahvaz city. Sequencing was used to purify the strains.
Genomic DNA gene extraction was performed using general primers and the gene related to
the ribosomal subunit (16S rRNA) was amplified. Phylogenetic analysis of the strains after
determining the similar sequences and aligning the sequences, editing and drawing the
phylogenetic tree with MEGA software (V.11) was performed.
Results: 50 strains of 8 bacterial families were isolated from water, sediments and fish. The
strains belonging to the Bacillus family had the highest frequency in water, sediment and
fish (P<0.05). Also, in all the sampling areas, the bacterial diversity in the sediment was
more than that of the water, and the composition of the bacterial community in the digestive
system of fishes was more similar to the sediments on the riverside.
Conclusion: According to the results of the present study and the effectiveness of fish gut
bacteria from sediments, knowing the natural bacterial flora of fish ecosystems can be
effective in managing aquatic ecosystems and using them for different uses. On the other
hand, due to the possibility of the spread of non-indigenous pathogens or resistant to
antibiotics as a result of human sewage entering the river, it seems necessary to maintain the
health of the river and purify the sewage before entering the Karoon River.