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Four Types of TiO₂ Reduced the Growth of Selected Lactic Acid Bacteria Strains.

ABSTRACT: Food-grade titanium dioxide (TiO₂) containing a nanoparticle fraction (TiO₂ NPs -nanoparticles) is widely used as a food additive (E171 in the EU). In recent years, it has increasingly been raising controversies as to the presence or absence of its harmful effects on the gastrointestinal microbiota. The complexity and variability of microbiota species present in the human gastrointestinal tract impede the assessment of the impact of food additives on this ecosystem. As unicellular organisms, bacteria are a very convenient research model for investigation of the toxicity of nanoparticles. We examined the effect of TiO₂ (three types of food-grade E171 and one TiO₂ NPs, 21 nm) on the growth of 17 strains of lactic acid bacteria colonizing the human digestive tract. Each bacterial strain was treated with TiO₂ at four concentrations (60, 150, 300, and 600 mg/L TiO₂). The differences in the growth of the individual strains were caused by the type and concentration of TiO₂. It was shown that the growth of a majority of the analyzed strains was decreased by the application of E171 and TiO₂ NPs already at the concentration of 150 and 300 mg/L. At the highest dose (600 mg/L) of the nanoparticles, the reactions of the bacteria to the different TiO₂ types used in the experiment varied.

SUBMITTER: Baranowska-Wojcik E

PROVIDER: S-EPMC8146636 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:The antibiotic resistances of 45 lactic acid bacteria strains belonging to the genera Lactobacillus, Streptococcus, Lactococcus, Pediococcus, and Leuconostoc were investigated. The objective was to determine antibiotic resistances and to verify these at the genetic level, as is currently suggested by the European "qualified presumption of safety" safety evaluation system for industrial starter strains. In addition, we sought to pinpoint possible problems in resistance determinations. Primers were used to PCR amplify genes involved in beta-lactam antibiotic, chloramphenicol, tetracycline, and erythromycin resistance. The presence of ribosomal protection protein genes and the ermB gene was also determined by using a gene probe. Generally, the incidences of erythromycin, chloramphenicol, tetracycline, or beta-lactam resistances in this study were low (<7%). In contrast, aminoglycoside (gentamicin and streptomycin) and ciprofloxacin resistances were higher than 70%, indicating that these may constitute intrinsic resistances. The genetic basis for ciprofloxacin resistance could not be verified, since no mutations typical of quinolone resistances were detected in the quinolone determining regions of the parC and gyrA genes. Some starter strains showed low-level ampicillin, penicillin, chloramphenicol, and tetracycline resistances, but no known resistance genes could be detected. Although some strains possessed the cat gene, none of these were phenotypically resistant to chloramphenicol. Using reverse transcription-PCR, these cat genes were shown to be silent under both inducing and noninducing conditions. Only Lactobacillus salivarius BFE 7441 possessed an ermB gene, which was encoded on the chromosome and which could not be transferred in filter-mating experiments. This study clearly demonstrates problems encountered with resistance testing, in that the breakpoint values are often inadequately identified, resistance genes may be present but silent, and the genetic basis and associated resistance mechanisms toward some antibiotics are still unknown.

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Four Types of TiO₂ Reduced the Growth of Selected Lactic Acid Bacteria Strains.

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Dataset Information

Four Types of TiO2 Reduced the Growth of Selected Lactic Acid Bacteria Strains.

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OmicsDI is part of the ELIXIR infrastructure

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Four Types of TiO₂ Reduced the Growth of Selected Lactic Acid Bacteria Strains.