SigB regulates stress resistance, glucose starvation, MnSOD production, biofilm formation, and root colonization in Bacillus cereus 905

Bacillus cereus is a foodborne pathogen that often persists in dairy environments and is associated with food poisoning and spoilage. This spore-forming bacterium has a high propensity to develop biofilms onto dairy processing equipment and resists to chemical cleaning and disinfecting. This study deals with the in vitro application of thyme oil-based sanitizer solutions against biofilms formed by B. cereus genotypes which persist in pasteurized-milk processing lines. The effect of Thymus ciliatus essential oil on B. cereus planktonic cells and biofilms was assessed. The oil was tested alone and in combination with organic acids or industrial cleaning agents, in order to improve the removal of B. cereus recurrent genotypes. Minimal inhibitory concentrations of planktonic growth (MICs), biofilm formation (MBIC) and biofilm eradication (MBEC) of oil and organic acids were evaluated by microdilution assays. Thyme oil was more effective than organic acids against B. cereus planktonic growth, biofilm formation and established bio-films. High values of MICs were obtained for the three organic acids tested (3.5-4.5%) in comparison with those of essential oil (0.082-0.088%). The combination of oil with other antimicrobials as acetic acid, NaOH or HNO3 improves their effectiveness against B. cereus biofilms. These oil-based sanitizer solutions allow complete B. cereus biofilm eradication and should be an attractive candidate for the control and removal of biofilms in the dairy envi-ronment.

Download Full-text

Bacillus velezensisWall Teichoic Acids Are Required for Biofilm Formation and Root Colonization

Applied and Environmental Microbiology ◽

10.1128/aem.02116-18 ◽

2018 ◽

Vol 85 (5) ◽

Cited By ~ 4

Author(s):

Zhihui Xu ◽

Huihui Zhang ◽

Xinli Sun ◽

Yan Liu ◽

Wuxia Yan ◽

...

Keyword(s):

Plant Growth ◽

Biofilm Formation ◽

Root Colonization ◽

Molecular Networks ◽

Model Organisms ◽

Bacillus Velezensis ◽

Content Type ◽

Plant Growth Promoting ◽

Colonization Process ◽

Growth Promoting

ABSTRACTRhizosphere colonization by plant growth-promoting rhizobacteria (PGPR) along plant roots facilitates the ability of PGPR to promote plant growth and health. Thus, an understanding of the molecular mechanisms of the root colonization process by plant-beneficialBacillusstrains is essential for the use of these strains in agriculture. Here, we observed that ansfpgene mutant of the plant growth-promoting rhizobacteriumBacillus velezensisSQR9 was unable to form normal biofilm architecture, and differential protein expression was observed by proteomic analysis. A minor wall teichoic acid (WTA) biosynthetic protein, GgaA, was decreased over 4-fold in the Δsfpmutant, and impairment of theggaAgene postponed biofilm formation and decreased cucumber root colonization capabilities. In addition, we provide evidence that the major WTA biosynthetic enzyme GtaB is involved in both biofilm formation and root colonization. The deficiency in biofilm formation of the ΔgtaBmutant may be due to an absence of UDP-glucose, which is necessary for the synthesis of biofilm matrix exopolysaccharides (EPS). These observations provide insights into the root colonization process by a plant-beneficialBacillusstrain, which will help improve its application as a biofertilizer.IMPORTANCEBacillus velezensisis a Gram-positive plant-beneficial bacterium which is widely used in agriculture. Additionally,Bacillusspp. are some of the model organisms used in the study of biofilms, and as such, the molecular networks and regulation systems of biofilm formation are well characterized. However, the molecular processes involved in root colonization by plant-beneficialBacillusstrains remain largely unknown. Here, we showed that WTAs play important roles in the plant root colonization process. The loss of thegtaBgene affects the ability ofB. velezensisSQR9 to sense plant polysaccharides, which are important environmental cues that trigger biofilm formation and colonization in the rhizosphere. This knowledge provides new insights into theBacillusroot colonization process and can help improve our understanding of plant-rhizobacterium interactions.

Download Full-text

Root colonization and growth promotion of soybean, wheat and Chinese cabbage by Bacillus cereus YL6

PLoS ONE ◽

10.1371/journal.pone.0200181 ◽

2018 ◽

Vol 13 (11) ◽

pp. e0200181 ◽

Cited By ~ 6

Author(s):

Yongli Ku ◽

Guoyi Xu ◽

Xiaohong Tian ◽

Huiqin Xie ◽

Xiangna Yang ◽

...

Keyword(s):

Bacillus Cereus ◽

Chinese Cabbage ◽

Root Colonization ◽

Growth Promotion

Download Full-text

Strain variation in Bacillus cereus biofilms and their susceptibility to extracellular matrix-degrading enzymes

PLoS ONE ◽

10.1371/journal.pone.0245708 ◽

2021 ◽

Vol 16 (6) ◽

pp. e0245708

Author(s):

Eun Seob Lim ◽

Seung-Youb Baek ◽

Taeyoung Oh ◽

Minseon Koo ◽

Joo Young Lee ◽

...

Keyword(s):

Extracellular Matrix ◽

Bacillus Cereus ◽

Biofilm Formation ◽

Dnase I ◽

Extracellular Dna ◽

Proteinase K ◽

Strain Variation ◽

Protein Ratio ◽

Degrading Enzymes ◽

Matrix Degrading Enzymes

Bacillus cereus is a foodborne pathogen and can form biofilms on food contact surfaces, which causes food hygiene problems. While it is necessary to understand strain-dependent variation to effectively control these biofilms, strain-to-strain variation in the structure of B. cereus biofilms is poorly understood. In this study, B. cereus strains from tatsoi (BC4, BC10, and BC72) and the ATCC 10987 reference strain were incubated at 30°C to form biofilms in the presence of the extracellular matrix-degrading enzymes DNase I, proteinase K, dispase II, cellulase, amyloglucosidase, and α-amylase to assess the susceptibility to these enzymes. The four strains exhibited four different patterns in terms of biofilm susceptibility to the enzymes as well as morphology of surface-attached biofilms or suspended cell aggregates. DNase I inhibited the biofilm formation of strains ATCC 10987 and BC4 but not of strains BC10 and BC72. This result suggests that some strains may not have extracellular DNA, or their extracellular DNA may be protected in their biofilms. In addition, the strains exhibited different patterns of susceptibility to protein- and carbohydrate-degrading enzymes. While other strains were resistant, strains ATCC 10987 and BC4 were susceptible to cellulase, suggesting that cellulose or its similar polysaccharides may exist and play an essential role in their biofilm formation. Our compositional and imaging analyses of strains ATCC 10987 and BC4 suggested that the physicochemical properties of their biofilms are distinct, as calculated by the carbohydrate to protein ratio. Taken together, our study suggests that the extracellular matrix of B. cereus biofilms may be highly diverse and provides insight into the diverse mechanisms of biofilm formation among B. cereus strains.

Download Full-text

Inactivation of the Transcriptional Regulator-Encoding Gene sdiA Enhances Rice Root Colonization and Biofilm Formation in Enterobacter cloacae GS1

Journal of Bacteriology ◽

10.1128/jb.01236-12 ◽

2012 ◽

Vol 195 (1) ◽

pp. 39-45 ◽

Cited By ~ 9

Author(s):

M. Shankar ◽

P. Ponraj ◽

D. Illakkiam ◽

J. Rajendhran ◽

P. Gunasekaran

Keyword(s):

Biofilm Formation ◽

Root Colonization ◽

Transcriptional Regulator ◽

Enterobacter Cloacae ◽

Rice Root ◽

Encoding Gene

Download Full-text

Root Exudate-Induced Alterations in Bacillus cereus Cell Wall Contribute to Root Colonization and Plant Growth Promotion

PLoS ONE ◽

10.1371/journal.pone.0078369 ◽

2013 ◽

Vol 8 (10) ◽

pp. e78369 ◽

Cited By ~ 28

Author(s):

Swarnalee Dutta ◽

T. Swaroopa Rani ◽

Appa Rao Podile

Keyword(s):

Cell Wall ◽

Plant Growth ◽

Bacillus Cereus ◽

Plant Growth Promotion ◽

Root Exudate ◽

Root Colonization ◽

Growth Promotion

Download Full-text

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

Journal of Food Protection ◽

10.4315/0362-028x-68.12.2614 ◽

2005 ◽

Vol 68 (12) ◽

pp. 2614-2622 ◽

Cited By ~ 129

Author(s):

JEE-HOON RYU ◽

LARRY R. BEUCHAT

Keyword(s):

Stainless Steel ◽

Relative Humidity ◽

Bacillus Cereus ◽

Chlorine Dioxide ◽

Biofilm Formation ◽

Total Cell ◽

Stainless Steel Surface ◽

Peroxyacetic Acid ◽

Vegetative Cells ◽

Cell Counts

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.

Download Full-text