High-throughput discrimination of bacteria isolated fromAstacus astacusandA. leptodactylus

Abstract

Key-words: crayfish, bacteria, MALDI-TOF MS, API 20EBacterial diseases and pathogens of crayfish are common, widespread, and occasionally causing serious mortalities. In order to take rapid measures for correct treatment of crayfish diseases, the turnover time and accuracy in bacterial identification is an issue. Bacteria isolated from tissues of apparently healthy Astacus astacus and A. leptodactylus were identified by the commercial phenotypic tests (API 20E) and by the matrix assisted laser induced desorption ionization connected to the time of flight mass spectrometry (MALDI-TOF MS). For Gram-negative rods, API 20E resulted in fewer species identifications than MALDI-TOF MS (5.2% versus 52.61%). The most frequently identified genus from A. astacus and A. leptodactylus was Pseudomonas spp.: API 20E (47.82%) and MALDI-TOF MS (52.17%). Both systems identified 60.86% of total isolates identically to the genus. Hafnia alvei was the only isolate for which API 20E and MALDI-TOF MS had a concordant reading to the species. MALDI-TOF MS proved to be a powerful, low-cost, rapid tool in bacterial genus identification. This is the first report of a direct comparison between the two systems for the identification of bacteria in crayfish, and also the first report on using MALDI-TOF MS for discrimination of freshwater crayfish bacterial isolates. ont identifié 60,86 % des isolats totaux au même genre. Hafnia alvei était le seul isolat dont API 20E et MALDI-TOF MS ont une lecture concordante à l'espèce. MALDI-TOF MS s'est avéré être un outil rapide, puissant, à faible coût, pour l'identification au niveau du genre bactérien. Ce travail est le premier d'une comparaison directe entre les deux systèmes pour l'identification des bactéries chez les écrevisses, et aussi le premier travail sur l'utilisation de MALDI-TOF MS pour la discrimination des isolats bactériens d'écrevisses d'eau douce.

Differentiation of environmental aquatic bacterial isolates by MALDI-TOF MS

“…The need for comparison of MALDI-TOF MS data with results obtained from phenotypic and genotypic identification methods is still important for identification of environmental isolates. We confirmed that in our study where we isolated bacteria from tissues of apparently healthy freshwater crayfish (Topić Popović et al, 2014). From 25 relevant isolates, only one matched to the species when compared with conventional methods (Hafnia alvei), while API 20E and MALDI-TOF MS identified 60.86 % identically to the genus.…”

Microbial Evaluation of Ozone Water Combined with Ultrasound Cleaning on Crayfish (Procambarus clarkii)

“…Concretely, the abundance in OW, UL, and OCU were 14.83, 19.41, and 23.22%, respectively. Generally, Pseudomonas was considered to be the dominant microbiota in crayfish [ 45 , 60 ]. However, because the total microbial load was unknown, although the relative abundance of Pseudomonas increased, it was not known whether this phenomenon was due to an increase in its absolute quantity or a decrease in the abundance of other microbiota.…”

Detection and diversity of aeromonads from treated wastewater and fish inhabiting effluent and downstream waters

“…In contrast, different species of Aeromonas isolates were unambiguously separated by hierarchical clustering by MALDI TOF MS which also gave a very rapid characterization of bacteria at the genus, species and strain level, thus proving its potential for speciating the unknown environmental bacterial isolates (Topic Popovic et al, 2014), although environmental Aeromonas isolates have a wider phenotypic diversity than isola Q3 tes obtained from clinical samples (Donohue et al, 2007). The genus Aeromonas comprises of over 20 species, and some of them are phenotypically very similar.…”