Characterization of Vegetative Bacillus cereus and Bacillus subtilis Strains Isolated from Processed Cheese Products in an Italian Dairy Plant

Processed cheese is a commercial product characterized by high microbiological stability and extended shelf life obtained through the application of severe heat treatment. However, spore-forming bacteria can survive through thermal processes. Among them, microorganisms belonging to Bacillus...

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Autores principales:	Angela Maria Catania, Tiziana Civera, Pierluigi Aldo Di Ciccio, Maria Ausilia Grassi, Patrizia Morra, Alessandra Dalmasso
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	spoilage <i>Bacillus cereus</i> <i>Bacillus subtilis</i> MLST toxins biofilm Chemical technology TP1-1185
Acceso en línea:	https://doaj.org/article/15a6997dedb44684a6a34a50d143420e
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spelling	oai:doaj.org-article:15a6997dedb44684a6a34a50d143420e2021-11-25T17:36:49ZCharacterization of Vegetative <i>Bacillus cereus</i> and <i>Bacillus subtilis</i> Strains Isolated from Processed Cheese Products in an Italian Dairy Plant10.3390/foods101128762304-8158https://doaj.org/article/15a6997dedb44684a6a34a50d143420e2021-11-01T00:00:00Zhttps://www.mdpi.com/2304-8158/10/11/2876https://doaj.org/toc/2304-8158Processed cheese is a commercial product characterized by high microbiological stability and extended shelf life obtained through the application of severe heat treatment. However, spore-forming bacteria can survive through thermal processes. Among them, microorganisms belonging to <i>Bacillus</i> genus have been reported. In this study, we examined the microbiological population of the first hours’ production of processed cheeses in an Italian dairy plant during two seasons, between June and October 2020. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to identify bacteria colonies, allowing the isolation of <i>Bacillus cereus</i> and <i>Bacillus</i><i>subtilis</i> strains. These results were further confirmed by amplification and sequencing of 16 rRNA bacterial region. A multi-locus sequence type (MLST) analysis was performed to assess the genetic similarity among a selection of isolates. The fourteen <i>B. cereus</i> strains showed two sequence types: ST-32 was observed in only one strain and the ST-371 in the remaining thirteen isolates. On the contrary, all twenty-one <i>B. subtlis</i> strains, included in the study, showed a new allelic profile for the <i>pycA</i> gene, resulting in a new sequence type: ST-249. For <i>B. cereus</i> strains, analysis of toxin genes was performed. All isolates were positive for <i>nheABC</i>, <i>entFM</i>, and <i>cytK</i>, while <i>hblABCD</i>, <i>bceT</i>, and <i>ces</i> were not detected. Moreover, the biofilm-forming ability of <i>B. cereus</i> and <i>B. subtilis</i> strains was assessed, and all selected isolates proved to be biofilm formers (most of them were stronger producers). Considering the genetical similarity between isolates, jointly with the capacity to produce biofilm, the presence of a recurring <i>Bacillus</i> population could be hypothesized.Angela Maria CataniaTiziana CiveraPierluigi Aldo Di CiccioMaria Ausilia GrassiPatrizia MorraAlessandra DalmassoMDPI AGarticlespoilage<i>Bacillus cereus</i><i>Bacillus subtilis</i>MLSTtoxinsbiofilmChemical technologyTP1-1185ENFoods, Vol 10, Iss 2876, p 2876 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	spoilage <i>Bacillus cereus</i> <i>Bacillus subtilis</i> MLST toxins biofilm Chemical technology TP1-1185
spellingShingle	spoilage <i>Bacillus cereus</i> <i>Bacillus subtilis</i> MLST toxins biofilm Chemical technology TP1-1185 Angela Maria Catania Tiziana Civera Pierluigi Aldo Di Ciccio Maria Ausilia Grassi Patrizia Morra Alessandra Dalmasso Characterization of Vegetative <i>Bacillus cereus</i> and <i>Bacillus subtilis</i> Strains Isolated from Processed Cheese Products in an Italian Dairy Plant
description	Processed cheese is a commercial product characterized by high microbiological stability and extended shelf life obtained through the application of severe heat treatment. However, spore-forming bacteria can survive through thermal processes. Among them, microorganisms belonging to <i>Bacillus</i> genus have been reported. In this study, we examined the microbiological population of the first hours’ production of processed cheeses in an Italian dairy plant during two seasons, between June and October 2020. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to identify bacteria colonies, allowing the isolation of <i>Bacillus cereus</i> and <i>Bacillus</i><i>subtilis</i> strains. These results were further confirmed by amplification and sequencing of 16 rRNA bacterial region. A multi-locus sequence type (MLST) analysis was performed to assess the genetic similarity among a selection of isolates. The fourteen <i>B. cereus</i> strains showed two sequence types: ST-32 was observed in only one strain and the ST-371 in the remaining thirteen isolates. On the contrary, all twenty-one <i>B. subtlis</i> strains, included in the study, showed a new allelic profile for the <i>pycA</i> gene, resulting in a new sequence type: ST-249. For <i>B. cereus</i> strains, analysis of toxin genes was performed. All isolates were positive for <i>nheABC</i>, <i>entFM</i>, and <i>cytK</i>, while <i>hblABCD</i>, <i>bceT</i>, and <i>ces</i> were not detected. Moreover, the biofilm-forming ability of <i>B. cereus</i> and <i>B. subtilis</i> strains was assessed, and all selected isolates proved to be biofilm formers (most of them were stronger producers). Considering the genetical similarity between isolates, jointly with the capacity to produce biofilm, the presence of a recurring <i>Bacillus</i> population could be hypothesized.
format	article
author	Angela Maria Catania Tiziana Civera Pierluigi Aldo Di Ciccio Maria Ausilia Grassi Patrizia Morra Alessandra Dalmasso
author_facet	Angela Maria Catania Tiziana Civera Pierluigi Aldo Di Ciccio Maria Ausilia Grassi Patrizia Morra Alessandra Dalmasso
author_sort	Angela Maria Catania
title	Characterization of Vegetative <i>Bacillus cereus</i> and <i>Bacillus subtilis</i> Strains Isolated from Processed Cheese Products in an Italian Dairy Plant
title_short	Characterization of Vegetative <i>Bacillus cereus</i> and <i>Bacillus subtilis</i> Strains Isolated from Processed Cheese Products in an Italian Dairy Plant
title_full	Characterization of Vegetative <i>Bacillus cereus</i> and <i>Bacillus subtilis</i> Strains Isolated from Processed Cheese Products in an Italian Dairy Plant
title_fullStr	Characterization of Vegetative <i>Bacillus cereus</i> and <i>Bacillus subtilis</i> Strains Isolated from Processed Cheese Products in an Italian Dairy Plant
title_full_unstemmed	Characterization of Vegetative <i>Bacillus cereus</i> and <i>Bacillus subtilis</i> Strains Isolated from Processed Cheese Products in an Italian Dairy Plant
title_sort	characterization of vegetative <i>bacillus cereus</i> and <i>bacillus subtilis</i> strains isolated from processed cheese products in an italian dairy plant
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/15a6997dedb44684a6a34a50d143420e
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Characterization of Vegetative <i>Bacillus cereus</i> and <i>Bacillus subtilis</i> Strains Isolated from Processed Cheese Products in an Italian Dairy Plant

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