Evaluation of antibiotics as a methodological procedure to inhibit free-living and biofilm bacteria in marine zooplankton culture

Abstract

There is a problem with keeping culture medium completely or partially free from bacteria. The use of prokaryotic metabolic inhibitors, such as antibiotics, is suggested as an alternative solution, although such substances should not harm non-target organisms. Thus, the aim of this study was to assess the effectiveness of antibiotic treatments in inhibiting free-living and biofilm bacteria and their half-life in artificial marine environment using the copepod Acartia tonsa as bioindicador of non-harmful antibiotic combinations. Regarding to results, the application of 0.025 g L -1 penicillin G potassium + 0.08 g L -1streptomycin sulphate + 0.04 g L -1 neomycin sulphate showed great potential for use in marine cultures and scientific experiments without lethal effects to non-target organisms. The effect of this combination starts within the first six hours of exposure and reduces up to 93 % the bacterial density, but the half-life is short, requiring replacement. No adverse changes in water quality were observed within 168 hours of exposure. As a conclusion, we can infer that this treatment was an effective procedure for zooplankton cultures and scientific experiments with the aim of measuring the role of free-living and biofilm in the marine community.

Inhibition of biofilm bacteria and adherent fungi from marine plankton cultures using an antimicrobial combination

“…According to Lopes (2014), it is possible to apply up to 0.02 g L -1 nystatin in combination with antibiotics in cultures without lethal effects on A. tonsa for up to 48 h. There was a higher mortality of copepods in the treatments that showed the antifungal nystatin, probably because nystatin is a eukaryotic inhibitory substance (Groll et al 1999). The use of an antifungal, however, is essential for avoiding fungal contamination due to the ecological niche provided by bacteria (Agostini et al 2016). Diseases in cultures of invertebrates are caused by fungi of the genera Aspergillus, Penicillium, and Fusarium (Santos et al 2016).…”

“…n 2 showed inhibition in biofilm bacterial density of up to 94% compared to the control at 9-15 h of exposure. In this time interval, the microbial community started to restore, and a new dosage of antibiotics was necessary (Agostini et al 2016). Lopes (2014) obtained adherent bacterial reduction of up to 95% using the same combination of antimicrobials.…”

“…This study consisted of experiments to evaluate the effects of different antibiotics (penicillin, streptomycin and neomycin) at different concentrations (Agostini et al 2016;DeLorenzo et al 2001) administered in combination with nystatin (Finley 2012) (Table 1) to plankton cultures. The experimental organisms evaluated were Acartia tonsa Dana 1849 (Copepoda: Calanoida), Amphibalanus improvisus (Darwin 1854) (Crustacea: Cirripedia), and Conticribra weissflogii (Grunow) Stachura-Suchoples & Williams (Ochrophyta: Bacillariophyceae).…”

“…The detached biofilm solution was fixed with 4% sterile formaldehyde, placed inside Eppendorf tubes, and stored in the dark at 8°C until analysis. Biofilm bacterial density (org cm -2 ) was estimated in a flow cytometer (BD FACSVerse TM ) at the Faculty of Pharmacy of the Federal University of Rio Grande do Sul (UFRGS) (Agostini et al 2016(Agostini et al , 2017. Table 2 Summary of the treatments tested on target (bacteria and fungi) and experimental (copepod, barnacle, microalgae) organisms…”

The Effects of Antibiotics on Microbial Community Composition in an Estuary Reservoir during Spring and Summer Seasons

“…Results of sub-network further indicated that water temperature was the major environmental driving factor accelerated the Synechococcus growth, and chl-a concentration also significantly increased during this period ( Figure 6). In addition, several heterotrophic bacterial OTUs belonging to Actinobacteria, Gemmatimonadetes, Planctomycetes, Verrucomicrobia, β-and γ-Proteobacteria exhibited the co-occurrence patterns with Synechococcus, which indicated that mutualism mechanisms might exist between these bacterial taxa in aspect of carbon source utilization [40][41][42][43][44]. Further research is underway to confirm whether these related bacterial taxa can be bio-indicators to predict for the proliferation of Synechococcus.…”