Combined transcriptome and metabolome analyses reveal the potential mechanism for the inhibition of Penicillium digitatum by X33 antimicrobial oligopeptide

Penicillium digitatum is the primary spoilage fungus that causes green mold during postharvest in citrus. To reduce economic losses, developing more efficient and less toxic natural antimicrobial agents is urgently required. We previously found that the X33 antimicrobial oligopeptide (X33 AMOP), produced by Streptomyces lavendulae X33, exhibited a sterilization effect on P. digitatum. In this study, the effects, and physiological mechanisms of X33 AMOP as an inhibitor of P. digitatum were investigated. The transcriptional and metabolome profiling of P. digitatum exposed to X33 AMOP revealed 3648 genes and 190 metabolites that were prominently changed. The omics analyses suggested that X33 AMOP mainly inhibited P. digitatum growth by affecting cell integrity, genetic information delivery, oxidative stress tolerance, and energy metabolism. These findings provide helpful information regarding the antimicrobial mechanism of X33 AMOP against P. digitatum at the molecular level and indicate that X33 AMOP is a potential candidate to control P. digitatum. Graphical Abstract

Standard for the Quantification of a Sterilization Effect Using an Artificial Intelligence Disinfection Robot

Recent outbreaks and the worldwide spread of COVID-19 have challenged mankind with unprecedented difficulties. The introduction of autonomous disinfection robots appears to be indispensable as consistent sterilization is in desperate demand under limited manpower. In this study, we developed an autonomous navigation robot capable of recognizing objects and locations with a high probability of contamination and capable of providing quantified sterilization effects. In order to quantify the 99.9% sterilization effect of various bacterial strains, as representative contaminants with robots operated under different modules, the operating parameters of the moving speed, distance between the sample and the robot, and the radiation angle were determined. We anticipate that the sterilization effect data we obtained with our disinfection robot, to the best of our knowledge, for the first time, will serve as a type of stepping stone, leading to practical applications at various sites requiring disinfection.

High-pressure thermal sterilization and ε-polylysine synergistically inactivates Bacillus subtilis spores by damaging its inner membrane

The study aimed to determine the sterilization effect of a combination of high-pressure thermal sterilization (HPTS) and ε-polylysine (PL) on Bacillus subtilis spores. The spores were treated with HPTS (550 MPa at 25°C, 65°C and 75°C) combining with ε-PL at 0.1% and 0.3%. The results showed that HPTS and ε-PL synergistically inactivated the spores. The increased temperature and ε-PL concentration decreased the number of surviving spores, with the maximal inactivation of the spores in the treatment of 550 MPa, 75°C combining with 0.3% ε-PL. The increases in the temperature and ε-PL concentration significantly increased the release of the intracellular components in the spore suspension, with the maximal value for the spores treated with 550 MPa, 75°C and 0.3% ε-PL. The maximal fluidity and permeability of the cell inner membrane were observed in the treatment of 550 MPa, 75°C combining with 0.3% ε-PL. Changes in membrane lipids were detected from 3000 to 2800 cm -1 by Fourier transform infrared spectroscopy. The results may provide new insights into the mechanism by which HPTS and ε-PL synergistically sterilize Bacillus subtilis spores.

Assessment of the Impact of Decellularization Methods on Mechanical Properties of Biocomposites Used as Skin Substitute

This work aimed to assess the impact of acellularization and sterilization methods on the mechanical properties of biocomposites used as a skin substitute. On the basis of the statistical analysis, it was ascertained that the values of the Young modulus for the samples before the sterilization process—only in the cases of substances such as: trypsin, 15% glycerol and dispase—changed in a statistically significant way. In the case of dispase, the Young modulus value before the sterilization process amounted to 66.6 MPa, for trypsin this value equalled 33.9 MPa, whereas for 15% glycerol it was 11 MPa. In the case of samples after the completion of the sterilization process, the analysis did not show any statistically significant differences between the obtained results of Young’s modulus depending on the respective reagents applied. It was confirmed that different methods of acellularization and the process of sterilization effect the alteration of mechanical properties of allogeneic skins. In the case of the decellularization method using SDS (Sodium Dodecyl Sulfate), liquid nitrogen and 85% glycerol the highest values of strain were observed. In the authors’ opinion, it is the above-mentioned methods that should be recommended in the process of preparation of skin substitutes.

Comparative Evaluation of the Sterilization Effect of Six Kinds of Commercial Disinfectants against Four Pathogenic Bacteria

The authors have requested that this preprint be withdrawn due to erroneous posting.

Comparative Evaluation of the Sterilization Effect of Six Kinds of Commercial Disinfectants against Four Pathogenic Bacteria

In this work, we systematically investigate the sterilization effect of six kinds of commonly used commercial disinfectants, including the DuPont Virkon disinfectant, peracetic acid disinfectant, sodium hypochlorite, bromogeramine disinfectant, water-soluble allicin, and absolute ethanol, against the Escherichia coli, Staphylococcus aureus, Monilia albican and Clostridium sporogenes. The inhibition zone was used to qualitatively determine the antibacterial effects of the six disinfectants, and then the minimum two-fold dilution method was used to quantitatively determine the minimum inhibitory concentration and minimum bactericidal concentration of the six disinfectants on the four pathogens. The result illustrated that the antibacterial effect of peracetic acid disinfectant is the best, and clostridium sporogenes is the most sensitive to it, followed by bromogermine disinfectant, which can inhibit the four pathogenic bacteria at the concentration recommended by the manufacturer. The antibacterial effect of DuPont Virkon disinfectant, sodium hypochlorite, water-soluble allicin and absolute ethanol is not as good as expected, and cannot inhibit the four kinds of pathogenic bacteria at the recommended concentration. In summary, the antibacterial effect of peracetic acid disinfectant is the strongest, followed by the bromogermine disinfectant, DuPont Virkon disinfectant, sodium hypochlorite and water-soluble allicin. The absolute ethanol exhibits the worst antibacterial properties.