Pseudomonas sp. as the causative agent of anomalous blue discoloration in Brazilian fresh soft cheese (Minas Frescal)

Abstract In this study, we investigated the anomalous blue discoloration in fresh cheeses produced in Brazil (Minas Frescal). Isolates (n = 31) obtained from Minas Frescal cheeses with blue discoloration and identified as Pseudomonas spp. through PCR. These isolates were characterised as able to produce a diffusible blue pigment in vitro at different temperatures (5, 14 and 25 °C) after 24 h of incubation. Two isolates (A006 and B157) were selected and subjected to whole-genome sequencing; an in silico multi-locus sequence typing identified one new allelic profile for B157 and showed that isolates that produce the blue discoloration possibly share a common evolutionary development. Furthermore, algorithms ANIb, GGDC and inferred tree from GBDP distances, allowed the identification of B157 as P. carnis and A006 as a potential novel species. For the first time, Pseudomonas strains that cause blue discoloration in Minas frescal cheese in Brazil were investigated and identified.