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Subject: search.filters.subject.Anoxybacillus flavithermus

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    Novel hyperthermoacidic archaeal enzymes for removal of thermophilic biofilms from stainless steel
    (Oxford University Press on behalf of Applied Microbiology International, 2023-06) Nam Y; Barnebey A; Kim HK; Yannone SM; Flint S
    AIMS: To test the efficacy of novel hot/acid hyperthermoacidic enzyme treatments on the removal of thermophilic spore-forming biofilms from stainless steel surfaces. METHODS AND RESULTS: The present study measured the efficacy of hyperthermoacidic enzymes (protease, amylase, and endoglucanase) that are optimally active at low pH (≈3.0) and high temperatures (≈80°C) at removing thermophilic bacilli biofilms from stainless steel (SS) surfaces. Plate counts, spore counts, impedance microbiology, as well as epifluorescence microscopy, and scanning electron microscopy (SEM) were used to evaluate the cleaning and sanitation of biofilms grown in a continuous flow biofilm reactor. Previously unavailable hyperthermoacidic amylase, protease, and the combination of amylase and protease were tested on Anoxybacillus flavithermus and Bacillus licheniformis, and endoglucanase was tested on Geobacillus stearothermophilus. In all cases, the heated acidic enzymatic treatments significantly reduced biofilm cells and their sheltering extracellular polymeric substances (EPS). CONCLUSIONS: Hyperthermoacidic enzymes and the associated heated acid conditions are effective at removing biofilms of thermophilic bacteria from SS surfaces that contaminate dairy plants.
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    Effect of cations on biofilm formation by Geobacillus species and Anoxybacillus flavithermus dairy isolates : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand
    (Massey University, 2013) Somerton, Benjamin Thomas
    The concentration of free cations is one factor that may influence biofilm formation and consequent contamination of milk formulations by Geobacillus spp. and Anoxybacillus flavithermus during the manufacture of milk powders. Culture optical densities were measured to show that Ca2+ and Mg2+ predominantly increased the planktonic growth of Geobacillus spp. and A. flavithermus cultures. Culture cell numbers were enumerated, and a protein quantification assay was used to indicate that increases in optical density elicited by Ca2+ and Mg2+ supplementation was due to increased production of bacterial surface protein rather than an increase in cell numbers. High individual concentrations of Na+, K+ or Ca2+ (63 – 250 mM) inhibited the planktonic growth of Geobacillus spp., and Mg2+ protected Geobacillus spp. from high, inhibitory concentrations of Na+, K+ or Ca2+. The number of viable cells attached to stainless steel coupons was enumerated to show that cation concentrations or the monovalent to divalent cation ratio (2:1 compared to 10:1) did not influence the transition of bacteria from a planktonic to surface-attached form, or the subsequent formation of an established biofilm. However, preconditioning of the bacteria with cations increased their subsequent attachment. It was proposed that the transition of bacteria from a planktonic to surface-attached form is primarily mediated by the expression of bacterial surface proteins, as induced by cation preconditioning. The number of attached Geobacillus spp. was up to 4 log CFU cm-2 lower, for up to 18 h of biofilm formation, in a milk formulation that had a high monovalent to divalent cation ratio (greater than 10:1) relative to a milk formulation that had a monovalent to divalent cation ratio that resembled that found in unprocessed milk. Supplementation of a milk formulation that had a high monovalent to divalent cation ratio with Ca2+ or Mg2+ fully alleviated the inhibitory effect of the milk formulation on biofilm formation by Geobacillus spp. It was concluded that there is potential for the total thermophile count in milk powders that have high monovalent to divalent cation ratios to be markedly reduced. This would increase the quality and selling price of the milk powders.
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    Surface characteristics of an adhesive thermophilic spore-forming Bacillus, isolated from milk powder : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand
    (Massey University, 2008) Palmer, Jon Stuart
    The growth of thermophiles during the manufacture of milk powder leads to a progressive increase in the number of thermophilic bacteria contaminating the final product. The limited residence time of the milk in the plant during milk powder manufacture and the concentration effect of converting milk into milk powder cannot explain the number of thermophiles found in the final product. This suggests that thermophiles are attaching to the large surface area of stainless steel found within a milk powder plant and then growing and developing into biofilms, with individual cells and/or biofilm fragments sloughing off into the product line and thus contaminating the final product. The aim of the present study was to investigate the attachment mechanisms that enable the thermophile Anoxybacillus flavithermus (B 1 2) to attach to stainless steel surfaces. Passing a B 1 2 culture through a column of stainless steel chips, collecting the first cells to pass through, re-culturing and repeating the process six times, resulted in the isolation of a mutant, labelled X7, with lO-fold reduced ability to attach to stainless steel as well as a reduced ability to attach to plastic and glass. A comparison of bacterial cell surface properties indicated that X7 was less hydrophobic than its parental strain B 1 2 . Cell surface charge measurements also suggest that X7 has less net negative surface charge. Disruption of extracellular polysaccharides and DNA appeared to have no effect on the attachment process. Removal of surface proteins caused a reduction in attachment of B 1 2 and X7 as well as a reduction in surface hydrophobicity suggesting surface protein involvement in both. Analysis by two-dimensional gel electrophoresis of lysozyme/mutanolysin extracted surface proteins revealed two proteins expressed at reduced levels in X 7 compared with B 1 2 . One protein was identified by mass spectrometry as the cytoplasmic enzyme Formate acetyltransferase. The role of Formate acetyltransferase and the second unidentified protein on the attachment process of Anoxybacillus flavithermus remains unclear.