Impact of Pseudomonas H6 surfactant on all external life cycle stages of the fish parasitic ciliate Ichthyophthirius multifiliis

Abstract

A bacterial biosurfactant isolated from Pseudomonas (strain H6) has previously been shown to have a lethal effect on the oomycete Saprolegnia diclina infecting fish eggs. The present work demonstrates that the same biosurfactant has a strong in vitro antiparasitic effect on the fish pathogenic ciliate Ichthyophthirius multifiliis.Three life cycle stages (the infective theront stage, the tomont and the tomocyst containing tomites) were all susceptible to the surfactant. Theronts were the most sensitive showing 100% mortality in as low concentrations as 10 and 13 lg/ml within 30 min. Tomonts were the most resistant but were killed in concentrations of 100 lg/ml. Tomocysts, which generally are considered resistant to chemical and medical treatment, due to the surrounding protective cyst wall, were also sensitive.The surfactant, in concentrations of 10 and 13 lg/ml, penetrated the cyst wall and killed the enclosed tomites within 60 min. Rainbow trout fingerlings exposed to the biosurfactant showed no adverse immediate or late signs following several hours incubation in concentrations effective for killing the parasite. This bacterial surfactant may be further developed for application as an antiparasitic control agent in aquaculture. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Gill amoebae from freshwater rainbow trout (Oncorhynchus mykiss): In vitro evaluation of antiparasitic compounds againstVannellasp.

“…As oregano essential oil has been shown to be effective in prevention of infection with Ichthyobodo and Trichodina in Oncorhynchus keta (Mizuno et al, 2018), we also tested oregano and found it to be effective in killing amoebae at a concentration of 17.9 mg/ml and partly effective at a concentration of 8.9 mg/ml. The bacterial lipopeptide surfactant H6 was previously shown effective against theronts of the ciliate Ichthyophthirius (Al‐Jubury et al, 2018), and it was lethal to Vannella sp. but in a 25 times higher concentration (250 µg/ml).…”

“…from tilapia ( Oreochromis niloticus ) (Chitmanat, Tongdonmuan, & Nunsong, 2005), from European eel ( Anguilla anguilla ) (Madsen, Buchmann, & Mellergaard, 2000), Ichthyophthirius multifiliis from rainbow trout ( O. mykiss ) (Buchmann, Jensen, & Kruse, 2003) and Ichthyobodo and Trichodina from Oncorhynchus keta (Mizuno et al, 2018). In addition, a bacterial lipopeptide, a biosurfactant isolated from Pseudomonas (strain H6), is able to kill the oomycete Saprolegnia diclina infecting fish eggs (Liu et al, 2015) as well as three life cycle stages of the pathogenic ciliate Ichthyophthirius multifiliis (Al‐Jubury et al, 2018).…”

Immunomodulatory Role of Microbial Surfactants, with Special Emphasis on Fish

“…A biosurfactant isolated from a Pseudomonas strain had strong in vitro antiparasitic effect against the fish pathogenic ciliate Ichthyophthirius multifiliis . Further, effective doses (10 to 100 ug/mL) exhibited no adverse effects in rainbow trout fingerlings exposed to the biosurfactant, indicated the antiparasitic potential of the biosurfactant [ 82 ]. Phospholipopeptide BS isolated from Staphylococcus hominis was assessed for immunostimulatory activity in Oreochromis mossambicus [ 83 ].…”

Quantitative trait loci (QTL) associated with resistance of rainbow trout Oncorhynchus mykiss against the parasitic ciliate Ichthyophthirius multifiliis

“…The infected fish may mount a protective immune response (Bauer, 1953; Burkart, Clark, & Dickerson, 1990; Buschkiel, 1910; Dickerson & Clark, 1998; Goven, Dawe, & Gratzek, 1980; Hines & Spira, 1974; Moreira, Shoemaker, Zhang, & Xu, 2016; Sigh & Buchmann, 2001; Wang, Yu, Zhang, & Xu, 2019), but the experimental vaccines investigated so far (Burkart et al., 1990; He et al., 1997; Jørgensen et al, 2017; Ling, Sin, & Lam, 1993; Martins, Xu, Shoemaker, & Klesius, 2011; Wang, Clark, Noe, & Dickerson, 2002; Xu, Zhang, Shoemaker, & Beck, 2019) have not yet resulted in a marketable protective formulation. A number of chemotherapeutants have been successfully applied in the laboratory (Al‐Jubury et al., 2018; Picon‐Camacho, Marcos‐Lopez, & Shinn, 2012), but at farm level frequent usage of formalin, peracetic acid, sodium percarbonate and hydrogen peroxide remains the preferred control strategy (Heinecke & Buchmann, 2009; Meinelt et al., 2009; Rach, Gaikowski, & Ramsay, 2000). A genetic component associated with susceptibility and resistance to infection has been suggested in rainbowfish (Gleeson, McCalum, & Owens, 2000), leaving relevant possibilities for genetic selection of disease‐resistant strains.…”