Helicobacter pylori release from yeast as a vesicle‐encased or free bacterium

Abstract

Background Yeast has been suggested as a potent reservoir of H. pylori that facilitates bacterial spread within human populations. What mechanism ensures effective H. pylori release from yeast? Here, H. pylori release from yeast as a vesicle‐encased or free bacterium was studied. Materials and methods Liquid culture of Candida yeast was examined by light, fluorescence and transmission electron microscopy methods to observe the released vesicles. Vesicles were isolated and examined by TEM. Immunogold labeling was used for detection of H. pylori‐specific proteins in vesicles’ membrane. Free bacterial cells, released from yeast, were separated by immunomagnetic separation and observed by field emission scanning electron microscopy (FESEM). DNA of bead‐bound bacteria was used for amplification of H. pylori‐16S rDNA. Viability of bead‐bound bacteria was examined by live/dead stain and cultivation on Brucella blood agar. Results Microscopic observations showed that vesicles contained bacterium‐like structures. Thin sections showed release of vesicle‐encased or free bacterium from yeast. Immunogold labeling revealed occurrence of H. pylori proteins in vesicles’ membrane. FESEM showed attachment of H. pylori cells to magnetic beads. Sequencing of 521 bp PCR product confirmed the identity of bead‐bound H. pylori. Live/dead staining showed viability of bead‐bound H. pylori but the result of culture was negative. Conclusions Escape of intracellular H. pylori from yeast as a membrane‐bound or free bacterium indicates that H. pylori uses safe exit mechanisms that do not damage the host which is the principle of symbiotic associations. In human stomach, certain conditions may stimulate yeast cells to release H. pylori as a vesicle‐encased or free bacterium.

Fungal Sticky Porous Cell Wall Evolved for Efficient Uptake and Export

“…Release of vesicles has been reported in Cryptococcus neoformans, Paracoccidioides brasiliensis, Saccharomyces cerevisiae, and C. albicans (Da Silva et al 2015). In our previous study, the diameter of released vesicles from C. albicans was estimated as 50-800 nm (Heydari et al 2020) which was larger than the size of cell wall pores reported as 200-400 nm in S. cerevisiae (de Souza Pereira and Geibel 1999). In the present study, release of vesicles with different size, morphology and cargo from yeast indicated the exibility of their membranous structure.…”

“…On the one hand, the size of cell wall pores in Saccharomyces cerevisiae has been measured between 200 and 400 nm (de Souza Pereira and Geibel 1999). On the other hand, the size of extracellular vesicles (EVs) that could traverse the cell wall has been estimated as 60-300 nm in Cryptococcus neoformans (Rodrigues et al 2007), 50-500 nm in S. cerevisiae (Oliveira et al 2010) and 50-800 nm in C. albicans (Heydari et al 2020). By observing that the size of fungal exported vesicles often exceeded the exclusion size estimated for cell wall permeability, it was suggested that vesicles with lipid bilayer structure can compress to traverse the cell wall pores smaller than their diameter (Casadevall et al 2009).…”

Helicobacter pylori, Protected from Antibiotics and Stresses Inside Candida albicans Vacuoles, Cause Gastritis in Mice

“…The endosymbiosis of H. pylori in yeast cells was indicated by the presence of H. pylori in Candida cytosols, referred to as “intravacuolar H. pylori ”, as previously mentioned [ 45 , 46 ]. As such, H. pylori and C. albicans were co-incubated under different conditions, including the bacteria– Candida ratio, pH of the media, and duration of incubation); the result was the identification of H. pylori inside Candida yeast cells, as illustrated by bacteria-like bodies (BLBs) (dense black dots in a state of movement) inside the yeast cells [ 40 , 41 , 43 , 47 , 48 , 49 , 50 ], using bright-field microscopy ( Figure 1 ). With continuous time-frame illustrations, the movements of the dense black dots could be observed ( Figure 1 ), supporting the possible existence of BLBs inside the yeast cells.…”

Helicobacter pylori in the Oral Cavity: Current Evidence and Potential Survival Strategies

“…H. pylori can invade the C. albicans yeast cells and was strained green by live/dead BacLight staining, indicating that H. pylori can survive within C. albicans [ 118 , 119 ]. Consistent with this phenomenon, fast-moving bacteriolar-like bodies (BLBs) were observed within the vacuoles of the C. albicans yeast cells and were subsequently identified as H. pylori using PCR and fluorescence in situ hybridization (FISH) techniques [ 122 , 130 ]. Some non-adaptive conditions, such as nutrient deprivation [ 116 ], acidic pH [ 121 ], amoxicillin [ 120 ], and other stress factors, can further induce H. pylori to invade yeast cells.…”

“…Invading H. pylori can propagate vertically to the vacuoles of daughter cells of yeasts in consecutive subcultures of yeasts [ 118 ]. Moreover, vesicle-encased or free H. pylori can be released by C. albicans , and the released H. pylori may invade new C. albicans yeast cells [ 122 ]. In addition to transmission between yeast cells, the H. pylori can spread within yeast cells to various human bodies and niches.…”