Biofilm Formation and Sporulation by Bacillus cereus on a Stainless Steel Surface and Subsequent Resistance of Vegetative Cells and Spores to Chlorine, Chlorine Dioxide, and a Peroxyacetic Acid–Based Sanitizer

2005 ◽  
Vol 68 (12) ◽  
pp. 2614-2622 ◽  
Author(s):  
JEE-HOON RYU ◽  
LARRY R. BEUCHAT

Biofilm formation by Bacillus cereus 038-2 on stainless steel coupons, sporulation in the biofilm as affected by nutrient availability, temperature, and relative humidity, and the resistance of vegetative cells and spores in biofilm to sanitizers were investigated. Total counts in biofilm formed on coupons immersed in tryptic soy broth (TSB) at 12 and 22°C consisted of 99.94% of vegetative cells and 0.06% of spores. Coupons on which biofilm had formed were immersed in TSB or exposed to air with 100, 97, 93, or 85% relative humidity. Biofilm on coupons immersed in TSB at 12°C for an additional 6 days or 22°C for an additional 4 days contained 0.30 and 0.02% of spores, respectively, whereas biofilm exposed to air with 100 or 97% relative humidity at 22°C for 4 days contained 10 and 2.5% of spores, respectively. Sporulation did not occur in biofilm exposed to 93 or 85% relative humidity at 22°C. Treatment of biofilm on coupons that had been immersed in TSB at 22°C with chlorine (50 μg/ml), chlorine dioxide (50 μg/ml), and a peroxyacetic acid–based sanitizer (Tsunami 200, 40 μg/ml) for 5 min reduced total cell counts (vegetative cells plus spores) by 4.7, 3.0, and 3.8 log CFU per coupon, respectively; total cell counts in biofilm exposed to air with 100% relative humidity were reduced by 1.5, 2.4, and 1.1 log CFU per coupon, respectively, reflecting the presence of lower numbers of vegetative cells. Spores that survived treatment with chlorine dioxide had reduced resistance to heat. It is concluded that exposure of biofilm formed by B. cereus exposed to air at high relative humidity (≥97%) promotes the production of spores. Spores and, to a lesser extent, vegetative cells embedded in biofilm are protected against inactivation by sanitizers. Results provide new insights to developing strategies to achieve more effective sanitation programs to minimize risks associated with B. cereus in biofilm formed on food contact surfaces and on foods.

2009 ◽  
Vol 72 (3) ◽  
pp. 510-514 ◽  
Author(s):  
RICHARD PODOLAK ◽  
PHILIP H. ELLIOTT ◽  
BRADLEY J. TAYLOR ◽  
AAKASH KHURANA ◽  
DARRYL G. BLACK

A study was conducted to determine the effects of three commercially available disinfectants on the reduction of Alicyclobacillus acidoterrestris spores in single-strength apple juice applied to stainless steel surfaces. Apple juice was inoculated with A. acidoterrestris spores, spread onto the surface of stainless steel chips (SSC), dried to obtain spore concentrations of approximately 104 CFU/cm2, and treated with disinfectants at temperatures ranging from 40 to 90°C. The concentrations of disinfectants were 200, 500, 1,000, and 2,000 ppm of total chlorine for Clorox (CL) (sodium hypochlorite); 50, 100, and 200 ppm of total chlorine for Carnebon 200 (stabilized chlorine dioxide); and 1,500, 2,000, and 2,600 ppm for Vortexx (VOR) (hydrogen peroxide, peroxyacetic acid, and octanoic acid). For all temperatures tested, VOR at 2,600 ppm (90°C) and CL at 2,000 ppm (90°C) were the most inhibitory against A. acidoterrestris spores, resulting in 2.55- and 2.32-log CFU/cm2 reductions, respectively, after 2 min. All disinfectants and conditions tested resulted in the inactivation of A. acidoterrestris spores, with a maximum reduction of >2 log CFU/cm2. Results from this study indicate that A. acidoterrestris spores, in single-strength apple juice, may be effectively reduced on stainless steel surface by VOR and CL, which may have practical applications in the juice industry.


2006 ◽  
Vol 69 (8) ◽  
pp. 1892-1903 ◽  
Author(s):  
AUDREY C. KRESKE ◽  
JEE-HOON RYU ◽  
LARRY R. BEUCHAT

Chlorine (10 to 200 μg/ml), chlorine dioxide (10 to 200 μg/ml), and a peroxyacetic acid–based sanitizer (40 and 80 μg/ml) were evaluated for effectiveness in killing spores of Bacillus cereus and Bacillus thuringiensis in suspensions and on the surface of stainless steel and apples. Water and 5% horse serum were used as carriers for spore inoculum applied to the surface of stainless steel coupons, and 5% horse serum was used as a carrier for inoculum applied to apples. Inocula were dried on stainless steel for 5 h and on apples for 22 to 24 h before treating with sanitizers. At the concentrations of sanitizers tested, sensitivities of planktonic B. cereus and B. thuringiensis spores were similar. A portion of the spores surviving treatment with chlorine and, more markedly, chlorine dioxide had decreased tolerance to heat. Planktonic spores of both species were more sensitive to sanitizers than were spores on the surface of stainless steel or apples. At the same concentrations, chlorine was more effective than chlorine dioxide in killing spores in suspension and on stainless steel. The lethality of chlorine dioxide was markedly reduced when inoculum on stainless steel coupons was suspended in 5% horse serum as a carrier rather than water. Chlorine and chlorine dioxide at concentrations of 10 to 100 μg/ml were equally effective in killing spores on apples. Significant reductions of ≥3.8 to 4.5 log CFU per apple were achieved by treatment with 100 μg/ml of either of the two sanitizers. The peroxyacetic acid sanitizer (40 and 80 μg/ml) was ineffective in killing Bacillus spores in the test systems investigated. Results provide information on the effectiveness of sanitizers commonly used in the food processing industry in killing Bacillus spores in suspension, on a food-contact surface, and on a ready-to-eat food.


2019 ◽  
Vol 7 (11) ◽  
pp. 536 ◽  
Author(s):  
Mi Jin Kwon ◽  
Chae Lim Lee ◽  
Ki Sun Yoon

We investigated the ability of biofilm formation, survival, and behavior of diarrheal and emetic Bacillus cereus vegetative cells and spores in tofu. Both diarrheal and emetic B. cereus did not proliferate at a temperature below 9 °C in tofu. However, the emetic B. cereus grew faster than diarrheal B. cereus at 11 °C and had better survival ability at low temperatures. Both diarrheal and emetic B. cereus were able to form a biofilm on stainless steel. These biofilm cells were transferred to tofu in live state. The transferred biofilm cells could not grow at a temperature below 9 °C but grew over 11 °C, like planktonic cells. B. cereus contamination in tofu at a high concentration (>6 logs CFU/g) was not entirely killed by heating at 80, 85, or 90 °C for 2 h. Spores and emetic B. cereus had higher resistance to heat than vegetative cells and diarrheal B. cereus, respectively.


2012 ◽  
Vol 32 (1) ◽  
pp. 142-150 ◽  
Author(s):  
Danila Soares Caixeta ◽  
Thiago Henrique Scarpa ◽  
Danilo Florisvaldo Brugnera ◽  
Dieyckson Osvani Freire ◽  
Eduardo Alves ◽  
...  

The biofilm formation of Pseudomonas aeruginosa and Pseudomonas fluorescens on AISI 304 stainless steel in the presence of reconstituted skim milk under different temperatures was conducted, and the potential of three chemical sanitizers in removing the mono-species biofilms formed was compared. Pseudomonas aeruginosa cultivated in skim milk at 28 °C presented better growth rate (10.4 log CFU.mL-1) when compared with 3.7 and 4.2 log CFU.mL-1 for P. aeruginosa and P. fluorescens cultivated at 7 °C, respectively. Pseudomonas aeruginosa formed biofilm when cultivated at 28 °C. However, only the adhesion of P. aeruginosa and P. fluorescens was observed when incubated at 7 °C. The sodium dichloroisocyanurate was the most efficient sanitizer in the reduction of the adhered P. aeruginosa cells at 7 and 28 °C and those on the biofilm, respectively. The hydrogen peroxide was more effective in the reduction of adhered cells of P. fluorescens at 7 °C.


2003 ◽  
Vol 69 (7) ◽  
pp. 4329-4331 ◽  
Author(s):  
Belinda Galeano ◽  
Emily Korff ◽  
Wayne L. Nicholson

ABSTRACT Stainless steel surfaces coated with paints containing a silver- and zinc-containing zeolite (AgION antimicrobial) were assayed in comparison to uncoated stainless steel for antimicrobial activity against vegetative cells and spores of three Bacillus species, namely, B. anthracis Sterne, B. cereus T, and B. subtilis 168. Under the test conditions (25°C and 80% relative humidity), the zeolite coating produced approximately 3 log10 inactivation of vegetative cells within a 5- to 24-h period, but viability of spores of the three species was not significantly affected.


2020 ◽  
Vol 50 (3) ◽  
Author(s):  
Tatiane Viana Dutra ◽  
Daniela Biral do Prado ◽  
Márcia Maria dos Anjos ◽  
Miguel Machinski Junior ◽  
Jane Martha Graton Mikcha ◽  
...  

ABSTRACT: The objective of this study was to evaluate the effect of the initial microbial load, temperature and contact time on the biofilm formation of Alicyclobacillus acidoterrestris on stainless steel and natural food-grade rubber using orange juice as culture medium. The low initial load of A. acidoterrestris (2 log CFU/mL) led to biofilm formation on the stainless steel surface after 48 h of contact at 28 ºC and after 24 h at 45 ºC, and on natural food-grade rubber surface after 48 h of contact at both temperatures. The high initial microbial load (5 log CFU/mL) led to biofilm formation on stainless steel after 4 h of contact at 28 °C and 45 °C, while biofilm was formed on natural food-grade rubber after 8 h of contact at 28 °C and 4 h at 45 °C. The microbial load also affected the presence of spores in biofilm, which was observed on both surfaces only at high initial loads of A. acidoterrestris.


2005 ◽  
Vol 68 (8) ◽  
pp. 1734-1738 ◽  
Author(s):  
JEE-HOON RYU ◽  
HOIKYUNG KIM ◽  
LARRY R. BEUCHAT

A study was done to determine the effect of interacting factors on sporulation of Bacillus cereus in broth. Vegetative cells (1.4 to 2.2 log CFU/ml) of B. cereus strain 038-2 (capable of growing at 12°C) and strain F3812/84 (capable of growing at 8°C) were inoculated into 30 ml of tryptic soy broth (TSB), TSB supplemented with manganese (50 μg/ml), diluted (10%) TSB (dTSB), and dTSB supplemented with manganese (50 μg/ml) and incubated at 8, 12, or 22°C for up to 30, 30, or 10 days, respectively. Unheated and heated (80°C for 10 min) cultures were plated on brain heart infusion agar to determine total cell counts (vegetative cells plus spores) and the number of spores produced, respectively. Both strains of B. cereus survived in TSB and dTSB for 30 days at 8°C but did not sporulate. At 12°C, cells grew in TSB to a population of 6.0 ± 0.8 log CFU/ml, which was maintained for 30 days. Neither strain grew in dTSB at 12°C and survived for at least 30 days. Spores were not produced in any of the test broths at 12°C. At 22°C, cells reached a stationary growth phase between 12 and 24 h in TSB, TSB supplemented with manganese, and dTSB supplemented with manganese, and approximately 1% of the CFU were spores. In dTSB, cell growth and spore formation were retarded at 22°C and a significantly lower number of spores was produced compared with the number of spores produced in TSB, TSB supplemented with manganese, and dTSB supplemented with manganese. The addition of manganese to TSB did not affect cell growth or spore formation, but manganese did enhance sporulation in dTSB. This study provides useful information on spore formation by B. cereus as affected by conditions that may be imposed in liquid milieus on the surface of foods and on food contact surfaces in processing environments.


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