Adhesion and production of degrading enzymes by bacteria isolated from biofilms in raw milk cooling tanks

Flach, Juliana; Grzybowski, Valeska; Toniazzo, Geciane; Corção, Gertrudes

doi:10.1590/1678-457x.6374

Cited by 18 publications

(16 citation statements)

References 25 publications

(30 reference statements)

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“…As underlined above, the presence of biofilms in the food industry can result in food spoilage. Indeed, B. cereus strains produce extracellular proteases and lipases resulting in food degradation and spoilage, like sweet curdling and bitterness of milk sour taste, decreasing the shelf life of the product and therefore resulting in significant economic loss to food producers (Fromm and Boor, 2004 ; Flach et al, 2014 ). Even if present in raw milk at low concentration, Bacillus sp.…”

Section: Biofilms Control In the Food Environmentmentioning

confidence: 99%

Bacillus cereus Biofilms—Same, Only Different

Majed¹,

Faille²,

Kallassy³

et al. 2016

Front. Microbiol.

154

141

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Bacillus cereus displays a high diversity of lifestyles and ecological niches and include beneficial as well as pathogenic strains. These strains are widespread in the environment, are found on inert as well as on living surfaces and contaminate persistently the production lines of the food industry. Biofilms are suspected to play a key role in this ubiquitous distribution and in this persistency. Indeed, B. cereus produces a variety of biofilms which differ in their architecture and mechanism of formation, possibly reflecting an adaptation to various environments. Depending on the strain, B. cereus has the ability to grow as immersed or floating biofilms, and to secrete within the biofilm a vast array of metabolites, surfactants, bacteriocins, enzymes, and toxins, all compounds susceptible to act on the biofilm itself and/or on its environment. Within the biofilm, B. cereus exists in different physiological states and is able to generate highly resistant and adhesive spores, which themselves will increase the resistance of the bacterium to antimicrobials or to cleaning procedures. Current researches show that, despite similarities with the regulation processes and effector molecules involved in the initiation and maturation of the extensively studied Bacillus subtilis biofilm, important differences exists between the two species. The present review summarizes the up to date knowledge on biofilms produced by B. cereus and by two closely related pathogens, Bacillus thuringiensis and Bacillus anthracis. Economic issues caused by B. cereus biofilms and management strategies implemented to control these biofilms are included in this review, which also discuss the ecological and functional roles of biofilms in the lifecycle of these bacterial species and explore future developments in this important research area.

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Section: Biofilms Control In the Food Environmentmentioning

confidence: 99%

Bacillus cereus Biofilms—Same, Only Different

Majed¹,

Faille²,

Kallassy³

et al. 2016

Front. Microbiol.

154

141

View full text Add to dashboard Cite

show abstract

“…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.…”

Section: Sources Of Contamination Of Raw Milkmentioning

confidence: 99%

“…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 ).…”

Section: Control Of Spoilage By Heat-resistant Bacterial Enzymesmentioning

confidence: 99%

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

et al. 2017

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Raw bovine milk is highly nutritious as well as pH-neutral, providing the ideal conditions for microbial growth. The microbiota of raw milk is diverse and originates from several sources of contamination including the external udder surface, milking equipment, air, water, feed, grass, feces, and soil. Many bacterial and fungal species can be found in raw milk. The autochthonous microbiota of raw milk immediately after milking generally comprises lactic acid bacteria such as Lactococcus, Lactobacillus, Streptococcus, and Leuconostoc species, which are technologically important for the dairy industry, although they do occasionally cause spoilage of dairy products. Differences in milking practices and storage conditions on each continent, country and region result in variable microbial population structures in raw milk. Raw milk is usually stored at cold temperatures, e.g., about 4°C before processing to reduce the growth of most bacteria. However, psychrotrophic bacteria can proliferate and contribute to spoilage of ultra-high temperature (UHT) treated and sterilized milk and other dairy products with a long shelf life due to their ability to produce extracellular heat resistant enzymes such as peptidases and lipases. Worldwide, species of Pseudomonas, with the ability to produce these spoilage enzymes, are the most common contaminants isolated from cold raw milk although other genera such as Serratia are also reported as important milk spoilers, while for others more research is needed on the heat resistance of the spoilage enzymes produced. The residual activity of extracellular enzymes after high heat treatment may lead to technological problems (off flavors, physico-chemical instability) during the shelf life of milk and dairy products. This review covers the contamination patterns of cold raw milk in several parts of the world, the growth potential of psychrotrophic bacteria, their ability to produce extracellular heat-resistant enzymes and the consequences for dairy products with a long shelf life. This problem is of increasing importance because of the large worldwide trade in fluid milk and milk powder.

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“…Production of spores have been extensively documented in B. cereus biofilms ( Majed et al, 2016 ), a species genetically very close to B. thuringiensis , from which it differs mainly by the presence in the latter species of Cry plasmids involved in virulence against invertebrates ( Jensen et al, 2003 ). Indeed, spores and biofilms are the main causes of B. cereus persistent contamination of industrial food processing lines, which can lead to food spoilage and economical losses, particularly in the dairy industry ( Flach et al, 2014 ). However, the floating biofilm of B. cereus or of B. thuringiensis have, up to now, always been considered as a whole.…”

Section: Introductionmentioning

confidence: 99%

Spatio-Temporal Evolution of Sporulation in Bacillus thuringiensis Biofilm

et al. 2016

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Bacillus thuringiensis can produce a floating biofilm which includes two parts: a ring and a pellicle. The ring is a thick structure which sticks to the culture container, while the pellicle extends over the whole liquid surface and joins the ring. We have followed over time, from 16 to 96 h, sporulation in the two biofilm parts. Sporulation was followed in situ in 48-wells polystyrene microtiterplates with a fluorescence binocular stereomicroscope and a spoIID-yfp transcriptional fusion. Sporulation took place much earlier in the ring than in the pellicle. In 20 h-aged biofilms, spoIID was expressed only in the ring, which could be seen as a green fluorescent circle surrounding the non-fluorescent pellicle. However, after 48 h of culture, the pellicle started to express spoIID in specific area corresponding to protrusions, and after 96 h both the ring and the whole pellicle expressed spoIID. Spore counts and microscopy observations of the ring and the pellicle harvested separately confirmed these results and revealed that sporulation occured 24 h-later in the pellicle comparatively to the ring, although both structures contained nearly 100% spores after 96 h of culture. We hypothesize that two mechanisms, due to microenvironments in the biofilm, can explain this difference. First, the ring experiences a decreased concentration of nutrients earlier than the pellicle, because of a lower exchange area with the culture medium. An second, the ring is exposed to partial dryness. Both reasons could speed up sporulation in this biofilm structure. Our results also suggest that spores in the biofilm display a phenotypic heterogeneity. These observations might be of particular significance for the food industry, since the biofilm part sticking to container walls – the ring – is likely to contain spores and will therefore resist both to washing and to cleaning procedures, and will be able to restart a new biofilm when food production has resumed.

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Adhesion and production of degrading enzymes by bacteria isolated from biofilms in raw milk cooling tanks

Cited by 18 publications

References 25 publications

Bacillus cereus Biofilms—Same, Only Different

Bacillus cereus Biofilms—Same, Only Different

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

Spatio-Temporal Evolution of Sporulation in Bacillus thuringiensis Biofilm

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