Dissemination and persistence of Pseudomonas spp. in small-scale dairy farms

Abstract

This study was aimed at collecting data on presence, dissemination and persistence of Pseudomonas in small-scale dairy farms. Six farms (located in Piedmont) were visited three times over 2014: 116 waters (wells and different faucets/pipes) and 117 environmental samples (milking equipments and drains) were collected. Enumeration of Pseudomonadaceae was performed, 3-5 colonies/samples were selected for identification via 16SrDNA/oprI polymerase chain reaction (PCR), and typed by enterobacterial-repetitive-intergenic-consensus (ERIC)-PCR. Pseudomonadaceae were detected in 77% of samples. No statistical differences were found among proportions of positives across farms, sample typologies and seasons. Most isolates were Pseudomonas fluorescens (45%), and ERIC-PCR showed 32 persistent types diffused across farms. All in all, Pseudomonas spp. represents a challenge, considering its presence over time in water as well as in teat cups, indicating a continuous source of contamination. Moreover, persistency of strains may indicate biofilm-formation and/or sanitisers resistance, therefore emphasising the role of primary production for preventing milk contamination by Pseudomonas spp.

Effect of a pre-milking teat foam and a liner disinfectant on the presence of mesophilic and (proteolytic) psychrotrophic bacteria prior to milking

“…This is in contrast to the study of Nucera et al . (2016), where 45% of the proteolytic active pseudomonads in dairy environment were identified as P. fluorescens . However, these authors used another and probably less discriminatory method to identify the pseudomonads than the one that we used, which could explain the observed difference.…”

“…Therefore, preventing or reducing the number of psychrotrophs and pseudomonads entering the raw milk at the farm could be a useful control measure. Pseudomonads are widespread throughout the farm environment and are present on udders and the liners of the milking machine (Nucera et al ., 2016). Disinfectants used for teat dipping or liner disinfection are available and are frequently used for maintaining udder health.…”

Bacterial Succession through the Artisanal Process and Seasonal Effects Defining Bacterial Communities of Raw-Milk Adobera Cheese Revealed by High Throughput DNA Sequencing

“…Moreover, Pseudomonas spp. are considered a psychrotolerant bacterial contaminant related to spoilage of milk and dairy products; their incidence in raw-milk cheeses is associated with inadequate procedures of cleaning and sanitation (applied to milking machines, utensils, storage tanks, pipelines, and curding vats among others), via biofilm or by the use of contaminated water [ 57 , 58 , 59 ].…”

The Biodiversity of the Microbiota Producing Heat-Resistant Enzymes Responsible for Spoilage in Processed Bovine Milk and Dairy Products

“…Regarding milking hygiene practices, the cleanliness of milking equipment and storage tanks could affect the introduction and increase in the number of pathogens and other milk quality-affecting bacteria. The contaminant microbiota may persist in water, teat cups, and milking equipment over time indicating a continuous source of microorganisms ( Flach et al, 2014 ; Nucera et al, 2016 ). This persistence can possibly be explained by biofilm formation and consequent high resistance to disinfection.…”

“…It remains to be investigated whether such udder hygiene management strategies are also effective to reduce the psychrotrophic non-spore forming count in view of the study of Mallet et al (2012) which showed that teat care has more influence on the composition of technologically relevant microbial groups than on the composition of other groups such as Pseudomonas and other Gram-negative bacteria. This may indicate that control of biofilms in milk production and processing environments is maybe more important (reviewed by Marchand et al, 2012 ; Aswathanarayan and Vittal, 2014 ; Nucera et al, 2016 ), as release of vegetative cells or spoilage enzymes from these biofilms may compromise the quality of UHT products ( Flach et al, 2014 ; Teh et al, 2014b ). Prevention of biofilm formation may possibly be achieved by specific coating of stainless steel surfaces of milk equipment and milk storing tanks with spoilage bacteria, as was recently shown for milk spore-formers on plate heat exchanger surfaces ( Jindal et al, 2016 ).…”