Sporulation is dispensable for the vegetable‐associated life cycle of the human pathogen Bacillus cereus

AbstractBacillus cereus is a common food-borne pathogen that is responsible for important outbreaks of food poisoning in humans. Diseases caused by B. cereus usually exhibit two major symptoms, emetic or diarrheic, depending on the toxins produced. It is assumed that after the ingestion of contaminated vegetables or processed food, spores of enterotoxigenic B. cereus reach the intestine, where they germinate and produce the enterotoxins that are responsible for food poisoning. In our study, we observed that sporulation is required for the survival of B. cereus in leaves but is dispensable in ready-to-eat vegetables, such as endives. We demonstrate that vegetative cells of B. cereus that are originally impaired in sporulation but not biofilm formation are able to reach the intestine and cause severe disorders in a murine model. We propose that loss of part of the sporulation programme and reinforcement of structural factors related to adhesion, biofilm formation and pathogenic interaction with the host are adaptive traits of B. cereus with a life cycle primarily related to human hosts. Furthermore, our findings emphasise that the number of food poisoning cases associated with B. cereus is underestimated and suggest the need to revise the detection protocols, which are based primarily on spores and toxins.

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The Possible Transmission and Potential Enterotoxicity of Bacillus cereus on Lettuce Farms in Five Chinese Provinces

Frontiers in Microbiology ◽

10.3389/fmicb.2021.746632 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yang Qu ◽

Chao Wei ◽

Xiaohang Dai ◽

Yalong Bai ◽

Xin Zhao ◽

...

Keyword(s):

Bacillus Cereus ◽

Potential Risk ◽

Trace Analysis ◽

Multilocus Sequence Typing ◽

Soil Samples ◽

Foodborne Diseases ◽

Human Pathogen ◽

Toxin Genes ◽

Positive Rate ◽

Sequence Types

Bacillus cereus is a well-characterized human pathogen that produces toxins associated with diarrheal and emetic foodborne diseases. To investigate the possible transmission of B. cereus on lettuce farms in China and determine its enterotoxicity, (I) a total of 524 samples (lettuce: 332, soil: 69, water: 57, manure: 57, pesticide: 9) were collected from 46 lettuce farms in five Chinese provinces, (II) multilocus sequence typing (MLST) was used to classify B. cereus isolates and for trace analysis, and (III) the presence of toxin genes and enterotoxins (Hbl and Nhe) was detected in 68 strains. The results showed that one hundred and sixty-one lettuce samples (48.5%) tested positive for B. cereus at levels ranging from 10 to 5.3 × 104 CFU/g. Among the environmental sample categories surveyed, the highest positive rate was that of the pesticide samples at 55.6%, followed by soil samples at 52.2% and manure samples at 12.3%. Moreover, one hundred isolates of B. cereus yielded 68 different sequence types (STs) and were classified into five phylogenetic clades. Furthermore, Nhe toxin genes (nheA, nheB, nheC) were broadly distributed and identified in all 68 strains (100%), while Hbl toxin genes (hblA, hblC, hblD) were present in 61 strains (89.7%), entFM was detected in 62 strains (91.2%), and cytK was found in 29 strains (42.6%). All strains were negative for ces. As for the enterotoxin, Nhe was observed in all 68 isolates carrying nheB, while Hbl was present in 76.5% (52/68) of the strains harboring hblC. This study is the first report of possible B. cereus transmission and of its potential enterotoxicity on lettuce farms in China. The results showed that soil and pesticides are the main sources of B. cereus on lettuce farms in China, and the possible transmission routes are as follows: soil-lettuce, manure-lettuce, pesticide-lettuce, manure-soil-lettuce, and water-manure-soil-lettuce. Furthermore, the B. cereus isolates, whether from lettuce or the environment, pose a potential risk to health.

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Analysis of the Life Cycle of the Soil Saprophyte Bacillus cereus in Liquid Soil Extract and in Soil

Applied and Environmental Microbiology ◽

10.1128/aem.03076-05 ◽

2006 ◽

Vol 72 (7) ◽

pp. 4970-4977 ◽

Cited By ~ 106

Author(s):

Sébastien Vilain ◽

Yun Luo ◽

Michael B. Hildreth ◽

Volker S. Brözel

Keyword(s):

Organic Matter ◽

Life Cycle ◽

Bacillus Cereus ◽

Agar Medium ◽

Soil Extract ◽

Associated Bacteria ◽

Soil Microcosms ◽

Agar Surface ◽

Microscopic Inspection ◽

Current Paradigm

ABSTRACT Bacillus is commonly isolated from soils, with organisms of Bacillus cereus sensu lato being prevalent. Knowledge of the ecology of B. cereus and other Bacillus species in soil is far from complete. While the older literature favors a model of growth on soil-associated organic matter, the current paradigm is that B. cereus sensu lato germinates and grows in association with animals or plants, resulting in either symbiotic or pathogenic interactions. An in terra approach to study soil-associated bacteria is described, using filter-sterilized soil-extracted soluble organic matter (SESOM) and artificial soil microcosms (ASM) saturated with SESOM. B. cereus ATCC 14579 displayed a life cycle, with the ability to germinate, grow, and subsequently sporulate in both the liquid SESOM extract and in ASM inserted into wells in agar medium. Cells grew in liquid SESOM without separating, forming multicellular structures that coalesced to form clumps and encasing the ensuing spores in an extracellular matrix. Bacillus was able to translocate from the point of inoculation through soil microcosms as shown by the emergence of outgrowths on the surrounding agar surface. Microscopic inspection revealed bundles of parallel chains inside the soil. The motility inhibitor l-ethionine failed to suppress outgrowth, ruling out translocation by a flagellar-mediated mechanism such as swimming or swarming. Bacillus subtilis subsp. subtilis Marburg and four Bacillus isolates taken at random from soils also displayed a life cycle in SESOM and ASM and were all able to translocate through ASM, even in presence of l-ethionine. These data indicate that B. cereus is a saprophytic bacterium that is able to grow in soil and furthermore that it is adapted to translocate by employing a multicellular mode of growth.

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Microbicidal activity of crude extracts from Sargassum wightii against Bacillus cereus

International Current Pharmaceutical Journal ◽

10.3329/icpj.v3i10.20338 ◽

2014 ◽

Vol 3 (10) ◽

pp. 326-327 ◽

Cited By ~ 2

Author(s):

Amritha Krishna Bhuvaneshwari Venugopal ◽

Vinoth Kumar Thirumalairaj ◽

Geetharamani Durairaj ◽

Mahitha Puthanpurayal Vijayan ◽

Navya Lazar ◽

...

Keyword(s):

Petroleum Ether ◽

Bacillus Cereus ◽

Inhibitory Concentration ◽

Minimum Bactericidal Concentration ◽

Brown Seaweed ◽

Pharmaceutical Journal ◽

Human Pathogen ◽

Zone Of Inhibition ◽

Microbicidal Activity ◽

Crude Extracts

The present study was investigated to explore the antibacterial activity of four different solvent (petroleum ether, chloroform, acetone and ethanol) crude extracts of marine brown seaweed Sargassum wightti. Crude extracts were screened against human pathogen Bacillus cereus. The antibacterial efficiency was performed by agar well diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. The results revealed that the crude extract of petroleum ether showed prominent inhibiting activity against B. cereus and other crude extracts showed below detectable level. The highest microbicidal activity (zone of inhibition) 9.0 ± 0.32 mm was obtained at the concentration of 250 ?g /ml and the lowest activity was 3 ± 0.20 mm at 31.25 ?g /ml concentration. The MIC and MBC values were found to be 125 and 250 ?g /ml respectively. Results of this study suggested that the compounds present in the crude extracts of petroleum ether showed high activity against B. cereus and further studies are required to purify the active principles.DOI: http://dx.doi.org/10.3329/icpj.v3i10.20338 International Current Pharmaceutical Journal, September 2014, 3(10): 326-327

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Reference genes for quantitative, reverse-transcription PCR in Bacillus cereus group strains throughout the bacterial life cycle

Journal of Microbiological Methods ◽

10.1016/j.mimet.2011.05.006 ◽

2011 ◽

Vol 86 (2) ◽

pp. 210-217 ◽

Cited By ~ 44

Author(s):

Lillian Reiter ◽

Anne-Brit Kolstø ◽

Armin P. Piehler

Keyword(s):

Life Cycle ◽

Bacillus Cereus ◽

Reverse Transcription ◽

Reference Genes ◽

Bacillus Cereus Group ◽

Quantitative Reverse Transcription Pcr ◽

Reverse Transcription Pcr

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Bacillus Cereus Bacterium: A Human Pathogen

Annals of Applied Microbiology & Biotechnology Journal ◽

10.36876/aamb.1009 ◽

2018 ◽

Vol 2 (1) ◽

pp. 1-2

Author(s):

Karim Ennouri

Keyword(s):

Bacillus Cereus ◽

Human Pathogen

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Ultrastructural analysis of “Sensory” surface nerve endings and “putative” neurotransmitter sites in Schistosoma mansoni Miracidia

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100156791 ◽

1989 ◽

Vol 47 ◽

pp. 962-963

Author(s):

Betty Ruth Jones ◽

Steve Chi-Tang Pan

Keyword(s):

Nervous System ◽

Life Cycle ◽

Schistosoma Mansoni ◽

Snail Host ◽

Complex Life Cycle ◽

Rational Approach ◽

Effective Control ◽

The Social ◽

Social And Economic Development ◽

Basic Biology

INTRODUCTION: Schistosomiasis has been described as “one of the most devastating diseases of mankind, second only to malaria in its deleterious effects on the social and economic development of populations in many warm areas of the world.” The disease is worldwide and is probably spreading faster and becoming more intense than the overall research efforts designed to provide the basis for countering it. Moreover, there are indications that the development of water resources and the demands for increasing cultivation and food in developing countries may prevent adequate control of the disease and thus the number of infections are increasing.Our knowledge of the basic biology of the parasites causing the disease is far from adequate. Such knowledge is essential if we are to develop a rational approach to the effective control of human schistosomiasis. The miracidium is the first infective stage in the complex life cycle of schistosomes. The future of the entire life cycle depends on the capacity and ability of this organism to locate and enter a suitable snail host for further development, Little is known about the nervous system of the miracidium of Schistosoma mansoni and of other trematodes. Studies indicate that miracidia contain a well developed and complex nervous system that may aid the larvae in locating and entering a susceptible snail host (Wilson, 1970; Brooker, 1972; Chernin, 1974; Pan, 1980; Mehlhorn, 1988; and Jones, 1987-1988).

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A freeze-fracture-etched study of the physarum polycephalum plasma membrane during early formation of the macroplasmodial stage

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100147570 ◽

1993 ◽

Vol 51 ◽

pp. 346-347

Author(s):

Randolph W. Taylor ◽

Henrie Treadwell

Keyword(s):

Plasma Membrane ◽

Life Cycle ◽

Growth Phase ◽

Filter Paper ◽

Physarum Polycephalum ◽

Freeze Fracture ◽

Petri Dish ◽

Wire Screen ◽

Wide Mouth ◽

Sterile Filter

The plasma membrane of the Slime Mold, Physarum polycephalum, process unique morphological distinctions at different stages of the life cycle. Investigations of the plasma membrane of P. polycephalum, particularly, the arrangements of the intramembranous particles has provided useful information concerning possible changes occurring in higher organisms. In this report Freeze-fracture-etched techniques were used to investigate 3 hours post-fusion of the macroplasmodia stage of the P. polycephalum plasma membrane.Microplasmodia of Physarum polycephalum (M3C), axenically maintained, were collected in mid-expotential growth phase by centrifugation. Aliquots of microplasmodia were spread in 3 cm circles with a wide mouth pipette onto sterile filter paper which was supported on a wire screen contained in a petri dish. The cells were starved for 2 hrs at 24°C. After starvation, the cells were feed semidefined medium supplemented with hemin and incubated at 24°C. Three hours after incubation, samples were collected randomly from the petri plates, placed in plancettes and frozen with a propane-nitrogen jet freezer.

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