Isolation and Characterization of Acinetobacter lwoffii from the Intestine of Grass Carp (Ctenopharyngodon idella)

Abstract

Acinetobacter lwoffii infections are largely concentrated in mammals; very few reports are available for such infections in fish. In this study, a Gram-negative rod bacillus was isolated from the intestine of grass carp (Ctenopharyngodon idella), and designed as strain CY1. The isolated strain was then identified as A. lwoffii according to morphological, physiological, and biochemical properties, and 16S rDNA sequencing. The phylogenetic tree constructed on the basis of 16S rDNA sequences indicated that strain CY1 is most closely related to A. lwoffii, and has 98.08% similarity with type strain ATCC17925. Experimental infection assays were conducted, and a cumulative mortality rate of 75% was observed in grass carp. Antimicrobial susceptibility test showed that the isolated strain CY1 was highly susceptible to most antimicrobial agents tested, including aminoglycosides, β-lactams, and quinolones. To our knowledge, this is the first report on pathogenic A. lwoffii in grass carp.The IJA appears exclusively as a peer-reviewed on-line open-access journal at http://www.siamb.org.il. To read papers free of charge, please register online at registration form. Sale of IJA papers is strictly forbidden.

A Review of Grass Carp and Related Species Literature on Diet, Behavior, Toxicology, and Physiology Focused on Informing Development of Controls for Invasive Grass Carp Populations in North America

“…[889]). The CY1 strain of Acinetobacter lwoffii found in the intestines of grass carp causes hemorrhages on the fins and body and resulted in 75% mortality when grass carp were exposed to it [890]. Though the sample size for grass carp in this study was low, it suggests that grass carp have low susceptibility to CEV.…”

“…Paracoccus luteus is a species of aerobic, nonmotile, Gram-negative bacterium that was first isolated from grass carp intestines in Henan Province, China and described as new species in 2020 [989]. The aerobic, non-fermentative Gram-negative bacillus Acinetobacter lwoffii is found in the intestine of grass carp [890].…”

The Bacillus velezensis CYS06 Strain Exhibits Promising Applications in Fighting Grass Carp Bacterial Diseases

“…The grass carp is not only widely farmed in ponds, but it also widely distributed in streams, rivers, reservoirs, lakes, and wetlands to regulate water quality [1]. However, the grass carp, especially in ponds, is susceptible to various diseases, including bacterial septicemia caused by Aeromonas spp., viral hemorrhagic disease caused by grass carp reovirus (GCRV), and columnaris disease caused by Flavobacterium columnare [3][4][5]. Although GCRV severely affects grass carp aquaculture, vaccination is widely used in China to prevent and control GCRV.…”

“…Although GCRV severely affects grass carp aquaculture, vaccination is widely used in China to prevent and control GCRV. Bacterial diseases are common in grass carp aquaculture, and the main pathogens are F. columnare [3], Aeromonas hydrophila [4], Acinetobacter lwoffii [5],…”