Microbiology neutralization of zearalenone using Lactococcus lactis and Bifidobacterium sp.

The aim of the study was to neutralize zearalenone by lactic acid bacteria (LAB) such as Lactococcus lactis and Bifidobacterium sp. and investigate the mechanism of zearalenone (ZEA) binding. Neutralization of ZEA by LAB was confirmed by identification of binding kinetics and spectroscopic studies such as Fourier transform infrared spectroscopy (FT-IR) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The obtained results showed that the kinetic process of zearalenone binding to L. lactis is not homogeneous but is expressed with an initial rapid stage with about 90% of ZEA biosorption and with a much slower second step. In case of Bifidobacterium sp., the neutralization process is homogeneous; the main stage can be described with about 88% of ZEA biosorption. MALDI-TOF-MS measurements and FTIR analysis confirmed the uptake of zearalenone molecules by bacterial species. Moreover, the assessment of dead and live lactic acid bacteria cells after zearalenone treatment was performed using fluorescence microscopy. Graphical abstract Microbiology neutralization of zearalenone using Lactococcus lactis and Bifidobacterium sp. was confirmed by identification of binding kinetics and spectroscopic studies such as FT-IR spectroscopy and MALDI-TOF-MS spectrometry. The mechanism of ZEA binding was also investigated.

Zinc oxide nanoparticles: Synthesis, antiseptic activity and toxicity mechanism.

Zinc oxide (ZnO), as a material with attractive properties, has attracted great interest worldwide, particularly owing to the implementation of the synthesis of nano-sized particles. High luminescent efficiency, a wide band gap (3.36eV), and a large exciton binding energy (60meV) has triggered intense research on the production of nanoparticles using different synthesis methods and on their future applications. ZnO nanomaterials can be used in industry as nano-optical and nano-electrical devices, in food packaging and in medicine as antimicrobial and antitumor agents. The increasing focus on nano zinc oxide resulted in the invention and development of methods of nanoparticles synthesis. Recently, various approaches including physical, chemical and biological ("green chemistry") have been used to prepare ZnO nanocomposites with different morphologies. The obtained nanoparticles can be characterized with a broad range of analytical methods including dynamic light scattering (DLS), electron microscopy (TEM, SEM), UV-VIS spectroscopy, X-ray diffraction (XRD) or inductively coupled plasma with mass spectrometry (ICP-MS). With these it is possible to obtain information concerning the size, shape and optical properties of nanoparticles. ZnO NPs exhibit attractive antimicrobial properties against bacteria (Gram-positive and Gram-negative) and fungi. Zinc oxide nanocomposites show also selective toxicity toward normal and cancerous cells, which is explained by reactive oxygen formation (ROS). Yet despite the potentially interesting antitumor activity of ZnO nanoparticles, it has been proven that they can be also cytotoxic and genotoxic for multiple types of human cells (i.e. neuronal or epithelial cells). This paper reviews the methods of synthesizing zinc oxide nanocomposites as well as their characteristics, antimicrobial activity and cytotoxicity against normal and tumor cells.

Study of silver nanoparticles synthesized by acidophilic strain of Actinobacteria isolated from the of Picea sitchensis forest soil.

AIMS: In the present work the acidophilic actinobacteria strain was used as a novel reducing agent for the cheap, green and single-step synthesis of nanostructure silver particles. Structural, morphological and optical properties of the synthesized nanoparticles have been characterized by spectroscopy, dynamic light scattering and electron microscopy approach. The antimicrobial activity of silver nanoparticles against clinical strains such as Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis and Salmonella infantis alone and in combination with antibiotics were studied. METHODS AND RESULTS: The crystalline and stable biosynthesized silver nanoparticles ranged in size from 4 to 45 nm and were mostly spherical in shape being characterized evolving several analytical techniques. The bioAgNPs inhibited growth of most bacterial strains. The highest antimicrobial activity was observed against Ps. aeruginosa (10 mm), followed by Staph. aureus, B. subtilis and Pr. mirabilis (all 8 mm). The lower activity was noticed for E. coli and Kl. pneumoniae (6 and 2 mm, respectively). Moreover, the synergistic effect of bio(AgNPs) with various commercially available antibiotics was also evaluated. The most significant results were observed for bio(AgNPs) combined with tetracycline, kanamycin, ampicillin and neomycin, followed by streptomycin and gentamycin against E. coli, Salm. infantis and Kl. pneumoniae. The most resistant bacteria to commercial antibiotics was Pr. mirabilis. CONCLUSION: The Streptacidiphilus sp. strain CGG11n isolated from acidic soil can be used to efficiently synthesize the bioactive nanoparticles using inexpensive substances in an eco-friendly and nontoxic manner. The present work provides helpful insight into the development of new antimicrobial agents with the synergistic enhancement of the antibacterial mechanism against pathogenic micro-organisms. SIGNIFICANCE AND IMPACT OF THE STUDY: The synthesized silver bionanoparticles from Streptacidiphilus sp. strain CGG11n possess potent inhibitory effect that offers valuable contribution to pharmaceutical associations.