Characterization of thermophilic bacilli from a milk powder processing plant

Burgess, Sara; Flint, Steve; Lindsay, D.

doi:10.1111/jam.12366

Cited by 49 publications

(31 citation statements)

References 30 publications

(45 reference statements)

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“…Furthermore, during the manufacturing of milk powder from raw milk, concentrations of spores may increase in the product due to concentration effects or due to attachment of spores and growth of vegetative cells of these bacterial species in processing equipment, followed by spore formation (Burgess et al . ; Jindal and Anand ).…”

Section: Introductionmentioning

confidence: 97%

“…These spores are ubiquitously present on the cow and in its environment and can be introduced into the milk at low concentrations (<10 to 7 9 10 2 cfu/mL; Coorevits et al 2008) during milking. Furthermore, during the manufacturing of milk powder from raw milk, concentrations of spores may increase in the product due to concentration effects or due to attachment of spores and growth of vegetative cells of these bacterial species in processing equipment, followed by spore formation (Burgess et al 2014;Jindal and Anand 2018).…”

Section: Introductionmentioning

confidence: 99%

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Spores in dairy – new insights in detection, enumeration and risk assessment

Eijlander

Hekezen

Bienvenue³

et al. 2019

Int J of Dairy Tech

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The performance of the ISO method for the ‘Enumeration of the Specially Thermoresistant Spores of Thermophilic Bacteria in Dried Milk’ (ISO/TS27265; 2009) was compared with a more practical method. Both were tested for predictability of spoilage of UHT treated reconstituted milk. The data show that heating for 30 min at 100 °C has the same predictive value as heating for 30 min at 106 °C, provided that specifications are increased 1 log10 and the use of TSA as a cultivation medium is recommended over PCMA. Predictability of spoilage using classical plating methods is furthermore discussed in relation to variation in spore heat resistance of spores commonly present in the dairy industry.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Spores in dairy – new insights in detection, enumeration and risk assessment

Eijlander

Hekezen

Bienvenue³

et al. 2019

Int J of Dairy Tech

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“…These aerobic-spore-forming bacteria are frequent contaminants isolated from milk or dairy processing environments (Alvarez-Ordóñez et al 2014;Aouadhi et al 2013;Brown 2000;Buehner et al 2014;Burgess et al 2013;Flint et al 2001;Frank 1997;Lücking et al 2013;Masiello et al 2014) predominantly in milk powder (Reginensi et al 2001;Scott et al 2007;Yuan et al 2012) but not commonly reported in whey …”

Section: Pcr Identification and 16s Rdna Sequencingmentioning

confidence: 99%

“…Some of the bacteria isolated in the present trial could grow at both 30 and 55°C. Facultative thermophiles in dairy processing belong to the Bacillus genus and include species such as Bacillus coagulans, B. licheniformis and B. pumilus that are able to grow at both mesophilic and thermophilic temperatures (Burgess et al 2013;Flint et al 2011a, b).…”

Section: Isolation Of Bacteriamentioning

confidence: 99%

Characterisation and biofilm screening of the predominant bacteria isolated from whey protein concentrate 80

Zain

Flint

Bennett

et al. 2015

Dairy Sci. & Technol.

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The source of microbiological contamination of whey protein concentrate (WPC), a quality problem for the dairy industry, has not been thoroughly investigated. The objectives of this study were to identify the bacteria isolated from whey protein concentrate containing 80% protein (WPC 80) and determine their ability to form biofilms as a potential source of contamination in a whey processing line. Six Bacillus species including (percentage of isolates in brackets) Bacillus licheniformis (67%), Bacillus cereus (19%), Bacillus thuringensis (4%), Bacillus subtilis (4%), Bacillus pumilus (4%) and Paenibacillus glucanolyticus (2%) were identified based on BLAST databases in six different WPC80 batches. B. licheniformis was the predominant isolate. B. licheniformis are thermo-tolerant bacteria with the ability to form biofilm. This biofilm is a potential source of microbial contamination of product, resulting in microbial specification limits being exceeded. Spoilage of product may result from the metabolic products, such as enzymes, produced by these biofilms.

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“…isolated from the dairy industry in milk formulations A and B, although the degree of inhibition varied between strains. Strain variation in dairy isolates of Geobacillus has been reported (27) and is to be expected.…”

Section: Namentioning

confidence: 99%

Changes in Sodium, Calcium, and Magnesium Ion Concentrations That Inhibit Geobacillus Biofilms Have No Effect on Anoxybacillus flavithermus Biofilms

Somerton

Lindsay

Palmer

et al. 2015

Appl Environ Microbiol

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cThis study investigated the effects of varied sodium, calcium, and magnesium concentrations in specialty milk formulations on biofilm formation by Geobacillus spp. and Anoxybacillus flavithermus. The numbers of attached viable cells (log CFU per square centimeter) after 6 to 18 h of biofilm formation by three dairy-derived strains of Geobacillus and three dairy-derived strains of A. flavithermus were compared in two commercial milk formulations. Milk formulation B had relatively high sodium and low calcium and magnesium concentrations compared with those of milk formulation A, but the two formulations had comparable fat, protein, and lactose concentrations. Biofilm formation by the three Geobacillus isolates was up to 4 log CFU cm ؊2 lower in milk formulation B than in milk formulation A after 6 to 18 h, and the difference was often significant (P < 0.05). However, no significant differences (P < 0.05) were found when biofilm formations by the three A. flavithermus isolates were compared in milk formulations A and B. Supplementation of milk formulation A with 100 mM NaCl significantly decreased (P < 0.05) Geobacillus biofilm formation after 6 to 10 h. Furthermore, supplementation of milk formulation B with 2 mM CaCl 2 or 2 mM MgCl 2 significantly increased (P < 0.05) Geobacillus biofilm formation after 10 to 18 h. It was concluded that relatively high free Na ؉ and low free Ca 2؉ and Mg 2؉ concentrations in milk formulations are collectively required to inhibit biofilm formation by Geobacillus spp., whereas biofilm formation by A. flavithermus is not impacted by typical cation concentration differences of milk formulations.T hermophilic bacilli belonging to the Geobacillus spp. and Anoxybacillus flavithermus groups are the predominant spoilage bacteria that may contaminate milk during its manufacture into milk powder (1, 2). The number of thermophilic bacilli in milk powder is of major importance because it is a measure of its quality and determines its market selling price (1, 2). Geobacillus spp. and A. flavithermus grow as biofilms on product contact surfaces in regions of milk powder manufacturing plants, such as in plate heat exchangers and evaporators, that are held at high temperatures (up to 70°C) (1, 2). It is postulated that these biofilms act as a reservoir of cells that slough off and disperse into milk as it transits through the plant (1, 2). The majority of thermophilic bacilli that appear in milk powder originate from biofilms on product contact surfaces (2).The concentrations and ratios of free cations in the aqueous phase that immerses a biofilm can influence biofilms in many ways. Electrostatic interactions of free cations with bacterial polymers in a biofilm matrix can influence the structural integrity and cohesion of a biofilm (3, 4). In addition, bacteria respond to fluctuations in free cation concentrations by adapting their physiology, which may influence biofilm formation. For example, Kara et al. (5) showed that increasing Na ϩ concentrations increased the proportion of negatively char...

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Characterization of thermophilic bacilli from a milk powder processing plant

Cited by 49 publications

References 30 publications

Spores in dairy – new insights in detection, enumeration and risk assessment

Spores in dairy – new insights in detection, enumeration and risk assessment

Characterisation and biofilm screening of the predominant bacteria isolated from whey protein concentrate 80

Changes in Sodium, Calcium, and Magnesium Ion Concentrations That Inhibit Geobacillus Biofilms Have No Effect on Anoxybacillus flavithermus Biofilms

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