Bacillus Atrophaeus Research Articles

The Antibacterial Effect of the Films Coated with the Layers Based on Uncaria tomentosa and Formitopsis betulina Extracts and ZnO Nanoparticles and Their Influence on the Secondary Shelf-Life of Sliced Cooked Ham

Microbial surface contamination of the cooked ham sliced by shop assistants has an influence on its potential secondary shelf-life. Active packaging may be the solution. The first goal of the work was to obtain coatings based on Formitopsis betulina and Uncaria tomentosa extracts (separately), with the addition of nanoparticles of ZnO (as a synergetic agent to increase plant extracts’ antimicrobial effectiveness), that could be active against selected bacterial strains. Another aim of the work was to determine the influence of obtained active layers on microbial purity and texture of the samples. The results of the study demonstrated that the layers containing F. betulina or U. tomentosa extracts with the addition of ZnO nanoparticles inhibited Staphylococcus aureus, Bacillus atrophaeus, and Escherichia coli growth completely and decreased the number of Pseudomonas syringae cells. Analyzing microbial purity of sliced cooked ham portions after storage, it was observed that the active packaging based on U. tomentosa extracts had a greater influence on the total count than the coatings containing F. betulina extracts and that both active packaging materials affected the microbial purity of the cooked ham. Analyzing the textural parameter changes after 48 h of storage, a decrease in the gumminess, chewiness and cohesiveness values was noted, but only for the ham portions stored in bags covered with the coating based on U. tomentosa. The effectiveness of the active packaging on textural parameters after 96 h of storage was not noticed.

Fungal and Bacterial Bioagents Efficiency on the Control of Potato Pest Phthorimaea operculella via Ingestion or Contact

Potatoes are one of the most important food products in the world and considered a main human nutrition sources source. Potato tuber moth (Phthorimaea operculella Zeller (PTM) (Lepidoptera: Gelechiidae)) causes remarkable economic losses to important crop, both in field and under storage conditions In this study, the insecticidal efficiency of the following bioagents: Brevibacillus brevis (FD-1), Bacillus atrophaeus (FD 17), Bacillus sphaericus (FD 49), Bacillus cereus (FD 63), Vibrio hollisae (FD 70), Bacillus thuringiensis subsp. kenyae (FDP 8) bacteria strains and Beauveria bassiana fungal isolate (ET 10), were evaluated on their efficacy to control P. operculella, under controlled conditions. In addition to insecticidal efficacy evaluations, analyses were also carried out to determine the differences between bioagents action mode: (1) uptake (ingestion as a gastric poison) and (2) contact. For (1), 20 larvae were fed on the tubers immersed in these suspensions to analyze efficacy by ingestion; for (2), suspensions of 1x108 CFU/ml of bacteria and 5.7x105 conidia/ml of fungus were prepared and sprayed to 20 larvae. FD-63 (91.67%) and FD-17 (88.33%) taken up by diet gave the most effective results against the pest.

Biosynthesis of Copper Oxide and Silver Nanoparticles by Bacillus Spores and Evaluation of the Feasibility of Their Use in Antimicrobial Paints.

Modification of paint with nanoparticles (NPs) provides self-cleaning, water/dirt-repellent, and other properties. Therefore, the aim of the present study was to biosynthesize silver (Ag) and copper oxide (CuO) NPs and to prepare NP-modified paint. To this end, AgNPs and CuONPs were biosynthesized using Bacillus atrophaeus spores and commercial and crude dipicolinic acid (DPA) extracted from the spore of this bacterium. The synthesized NPs were characterized using electron microscopy, Fourier-transform infrared (FTIR), X-ray diffraction analysis (XRD), and energy-dispersive X-ray spectroscopy (EDS) methods. A minimum inhibitory concentration (MIC) assay of NPs against Escherichia coli ATCC8739 and Staphylococcus aureus ATCC6538 was carried out. The antibacterial effects of prepared NP-paint complexes were assessed using an optical density (OD) comparison before and after adding metal sheets coated with NP-paint complexes into the nutrient broth medium. Four different types of NPs were synthesized in this research: AgNPs synthesized by spore (A), AgNPs synthesized by commercial DPA (B), AgNPs synthesized by crude DPA (C), and CuONPs synthesized by spore (D). SEM analysis confirmed the spherical shape of NPs. According to the results, NPs A, B, and D showed higher antibacterial activity against S. aureus compared to E. coli. Furthermore, the analysis of the antibacterial effects of NP-paint complexes suggested that paint-NPs A, B, and C displayed higher activity on E. coli compared to S. aureus. Moreover, the antibacterial effect of paint-NP D was significantly lower than other NPs. According to this robust antibacterial effect on pathogenic bacteria, it seems that these NP-paint complexes could be useful in public places such as hospitals, airports, dormitories, schools, and office buildings, where the rate of transmission of infection is high.

A do-it-yourself test protocol using commercial Bacillus atrophaeus spores to evaluate the effectiveness of ultraviolet-C light room-decontamination devices.

We developed a do-it-yourself test protocol using commercial Bacillus atrophaeus spores to assess the efficacy of ultraviolet-C (UV-C) light room-decontamination devices. Overall, 4 UV-C devices reduced B. atrophaeus by ≥3 log10 colony-forming units in 10 minutes, whereas a smaller device required 60 minutes. Of 10 in-use devices, only 1 was ineffective.

Endophytic Bacillus atrophaeus CHGP13 and salicylic acid inhibit blue mold of lemon by regulating defense enzymes.

Lemons (Citrus limon L.) are one of the most economically important and consumed fruit worldwide. The species is vulnerable to several postharvest decay pathogens, of which Penicillium italicum associated with blue mold disease is the most damaging. This study investigates the use of integrated management for blue mold of lemon using lipopeptides (LPs) extracted from endophytic Bacillus strains and resistance inducers. Two resistance inducers; salicylic acid (SA) and benzoic acid (BA) were tested at 2, 3, 4, and 5 mM concentrations against the development of blue mold on lemon fruit. The 5 mM SA treatment produced the lowest disease incidence (60%) and lesion diameter (1.4 cm) of blue mold on lemon fruit relative to the control. In an in vitro antagonism assay eighteen Bacillus strains were evaluated for their direct antifungal effect against P. italicum; CHGP13 and CHGP17 had the greatest inhibition zones of 2.30 and 2.14 cm. Lipopeptides (LPs) extracted from CHGP13 and CHGP17 also inhibited the colony growth of P. italicum. LPs extracted from CHGP13 and 5 mM SA were tested as single and combined treatments against disease incidence and lesion diameter of blue mold on lemon fruit. SA + CHGP13 + PI had the lowest disease incidence (30%) and lesion diameter (0.4 cm) of P. italicum on lemon fruit relative to the other treatments. Furthermore, the lemon fruit treated with SA + CHGP13 + PI had the highest PPO, POD, and PAL activities. The postharvest quality analysis of the lemon fruit including fruit firmness, total soluble solids, weight loss, titratable acidity, and ascorbic acid content revealed that the treatment SA + CHGP13 + PI had little effect on fruit quality compared to the healthy control. These findings indicate that Bacillus strains and resistance inducers can be used as components of integrated disease management for the blue mold of lemon.

Bromine and Chlorine Disinfection of Cryptosporidium parvum Oocysts, Bacillus atrophaeus Spores, and MS2 Coliphage in Water.

Conventional water treatment practices utilizing chemical disinfection, especially chlorination, are considered generally effective in producing microbiologically safe drinking water. However, protozoan pathogens such as oocysts of Cryptosporidium parvum are very resistant to chlorine, which has led to consideration of alternative disinfectants for their control. Free bromine, HOBr, has not been evaluated extensively as an alternative halogen disinfectant for inactivation of Cryptosporidium parvum in drinking water or reclaimed water for non-potable uses. Bromine is a versatile disinfectant consisting of different chemical forms with persistent microbicidal efficacy under varied water quality conditions and is effective against a range of waterborne microbes of health concern. The objectives of this study are to (1) compare the efficacy of free bromine to free chlorine at similar concentrations (as milligrams per liter) for disinfection of Cryptosporidium parvum oocysts, Bacillus atrophaeus spores, and MS2 coliphage in a model buffered water and (2) evaluate the kinetics of inactivation of these microorganisms using appropriate disinfection models. Overall, at a target concentration of ∼5 mg/L, bromine averaged 0.6 log (73.8%) reductions of C. parvum oocyst infectivity after 300 min (CT: 1166 min·mg/L) and produced up to a 0.8 log reduction disinfectant activity. An ∼5.0 mg/L chlorine dose increased oocyst infectivity by only 0.4 log (64%) after 300 min (CT: 895 min·mg/L). Bacillus atrophaeus spores and MS2 coliphage treated with bromine and chlorine were reduced by 4 log10 (99.99%) for both disinfectants over the duration of the experiments.

Isolation and characterization of Priestia megaterium KD7 for the biological control of pear fire blight.

Erwinia amylovora is a plant pathogen that causes fire blight disease in Rosaceous plants, such as pear and apple. To develop an effective biocontrol method to suppress E. amylovora, a total of 16 bacteria were isolated from pear orchard soil in China and screened for antagonistic activity in vitro. Among them, 9 isolates that exhibited antagonistic activity against E. amylovora were identified, including Bacillus atrophaeus, Priestia megaterium (previously known as Bacillus megaterium) and Serratia marcescens based on the partial 16S rDNA sequence analysis and similarity search. The plate confrontation experiments showed that strain 8 (P. megaterium strain KD7) had strong antagonistic activity against E. amylovora. The methanolic extract from cell-free supernatant of strain KD7 displayed high antibacterial activities against E. amylovora. Furthermore, the active compounds of strain KD7 were separated by thin layer chromatography (TLC) and the amino acids were detected by the presence of a spot with retention factor (Rf) of 0.71. Next, three lipopeptides were identified with high-resolution mass spectrometry (HRMS), including C13-surfactin [M+H]+ at m/z 1008.14, C15-surfactin [M+H]+ at m/z 1036.50, and C14-iturin A [M+H]+ at m/z 1043.17. Strain KD7 showed multiple antibiotic resistance, such as ampicillin, erythromycin, penicillin and tetracycline. The detached pear leaves, twigs and fruits assay showed that both protective and curative action with strain KD7 had the ability to decrease the development of fire blight. Taken together, P. megaterium strain KD7 is a potential effective biocontrol agent against fire blight.

Двухфазный рост бактерий при использовании растительного масла в качестве единственного субстрата

The growth of four bacterial strains isolated from vegetable oil samples (Mp-2 Bacillus pumilus, Mp-4 Bacillus atrophaeus, Mp-6 Sphingomonas aurantiaca and Mp-7 Microbacterium oxydans) in vegetable oil at +7°C was studied. The previously isolated soil strain Mn5 of Rhodococcus erythropolis, capable of using vegetable oil as the only substrate, was used as an object for comparison. All strains showed the ability to grow in vegetable oil with a minimum generation time of 3.5 hours (Bacillus pumilus MP-2 strain) to 14.9 hours (Bacillus atropheus MP-4 strain). In most cases, the bacterial growth curves had two peaks, that is, they corresponded to biphasic growth. Two models are proposed to explain the observed growth curves. Keywords: VEGETABLE OIL, BACILLUS PUMILUS, BACILLUS ATROPHAEUS, SPHINGOMONAS AURANTIACA, MICROBACTERIUM OXYDANS, RHODOCOCCUS ERYTHROPOLIS, BIPHASIC GROWTH, COMPUTER MODELING

Influencing parameters of vaporized hydrogen peroxide on the sterilization of polyethylene terephthalate bottles

Hydrogen peroxide vapor sterilization of containers is commonly used in aseptic filling processes for liquid food such as dairy products. The sterilization of polyethylene terephthalate (PET) bottles presents a considerable challenge because of their temperature sensitivity. Therefore, the influence of the vapor temperature between 65 °C and 115 °C was considered, as it was significantly higher on other substrates in previous studies. An extensive Design of Experiments was conducted to determine the effects of different parameters and their interactions on the count reduction rate. The maximum observable count reduction rate was log (N0/N) = 6.6 for Bacillus atrophaeus DSM 675 spores. The count reduction rate could be positively influenced by increasing the gas temperature at liquid hydrogen peroxide (35% (v/v)) amounts above 0.186 mL for 500 mL bottles. Gas temperatures above 80 °C, in combination with the injection of vaporized H2O2 twice instead of once, increased the count reduction rates. By preheating the PET bottles to at least 35 °C and using a gas temperature of 80 °C, count reduction rates were higher than at lower temperatures. Not only the individual parameters but also their combinations had a significant effect on the inactivation of the spores.

Passenger vehicle interior decontamination by low concentration hydrogen peroxide vapor following a wide area biological contamination incident.

To assess low concentration hydrogen peroxide (LCHP) (H2O2) vapor dispersed with a home humidifier for its ability to decontaminate vehicle interiors contaminated with Bacillus anthracis surrogate Bacillus atrophaeus spores. Efficacy of a vaporized 3% H2O2 solution was evaluated for liquid volumes, on/off vehicle heating, ventilation, and air conditioning (HVAC) system operations, and temperatures that ranged from 5 to 27°C. Survival of the spores was assessed by quantification of remaining viable spores with efficacy quantified in terms of mean log10 reduction. Decontamination efficacy after the 6-day dwell time increased when the 3% H2O2 liquid volume was doubled, increasing from 4-of-10 to 10-of-10 nondetects (zero colonies counted using standard dilution and filter plating) inside the vehicle cabin. Recirculating cabin air through the HVAC system during decontamination decreased efficacy to 6-of-10 non-detects. While no 6-log10 reduction in viable spores was observed on the cabin filter with the cabin filter kept in place, a 6-log10 reduction was achieved after its removal and placement in the cabin during treatment. Results from this study allow for informed decisions on the use of LCHP vapor as an effective decontamination approach for vehicle interiors.

Isolation, identification and optimization of exopolysaccharide-based bioflocculant synthesis by soil bacteria Bacillus atrophaeus NR-12

Bioflocculants are polysaccharide-based, biodegradable macromolecules synthesized by soil microorganisms. A bacterium prodicing an extracellular bioflocculant wasisolated from the salty and dry soil and identified as Bacillus atrophaeus. Effects of culture conditions including carbon sources, nitrogen sources, pH, shaker speed on bioflocculant production were studied. Isolate comparative analysis of 16S rRNA sequence identified the isolate to have 99% similarity to Bacillus atrophaeus and it was deposited in the GenBank as Bacillus atrophaeus NR- 2 with accession number OP679007. The strain was characterized by ability to grow and synthesize the bioflocculant in alkaline conditions – pH 11. It was supposed that the strain can overcome adverse effects of environment – alkalinity and salinity by enhanced production of bioflocculant in stress. In the optimized medium (sucrose and tryptone used as C/N sources) the strain produced 4.76 mL bioflocculant.

Isolation, identification and optimization of exopolysaccharide-based bioflocculant synthesis by soil bacteria Bacillus atrophaeus NR-12

Bioflocculants are polysaccharide-based, biodegradable macromolecules synthesized by soil microorganisms. A bacterium prodicing an extracellular bioflocculant wasisolated from the salty and dry soil and identified as Bacillus atrophaeus. Effects of culture conditions including carbon sources, nitrogen sources, pH, shaker speed on bioflocculant production were studied. Isolate comparative analysis of 16S rRNA sequence identified the isolate to have 99% similarity to Bacillus atrophaeus and it was deposited in the GenBank as Bacillus atrophaeus NR- 2 with accession number OP679007. The strain was characterized by ability to grow and synthesize the bioflocculant in alkaline conditions – pH 11. It was supposed that the strain can overcome adverse effects of environment – alkalinity and salinity by enhanced production of bioflocculant in stress. In the optimized medium (sucrose and tryptone used as C/N sources) the strain produced 4.76 mL bioflocculant.

Effects of multiwalled carbon nanotube and Bacillus atrophaeus application on crop root zone thermal characteristics of saline farmland

Presently, the effects of crop roots on crop root zone thermal characteristics are poorly understood, and new fertilizers are rarely considered from the perspective of changing crop root zone thermal characteristics. This study explored the effect of applying two new fertilizers, multiwalled carbon nanotubes (MWCNTs) and Bacillus atrophaeus (B. atrophaeus), on the crop root zone thermal characteristics of saline farmland soils through in situ measurements. The results showed that MWCNTs and B. atrophaeus could indirectly affect crop root zone thermal characteristics by changing the crop root growth. Combined application of MWCNTs and B. atrophaeus could promote both to induce positive effects, promote crop root growth, and significantly alleviate the adverse effects of soil salinization. The thermal conductivity and heat capacity of the shallow root zone were reduced due to the presence of crop roots, while the opposite was true in the deep root zone. For example, the thermal conductivity of the 0–5 cm rich root zone in the MWCNT treatment was 0.8174 W m−1 ·K−1, and the thermal conductivity of the poor root zone was 13.42% higher than that of the rich root zone. MWCNTs and B. atrophaeus can also change the spatial distribution of soil moisture, soil salt, and soil particle size characteristics by influencing the root-soil interactions and indirectly affecting crop root zone thermal characteristics. In addition, MWCNTs and B. atrophaeus could directly affect the root zone thermal characteristics by changing the soil properties. The higher the soil salt content was, the more obvious the effect of the MWCNTs and B. atrophaeus on the crop root zone thermal characteristics. The thermal conductivity and heat capacity of the crop root zone were positively correlated with the soil moisture content, soil salt content and soil particle specific surface area and negatively correlated with the soil particle size and the fresh and dry root weights. In summary, MWCNTs and B. atrophaeus significantly affected crop root zone thermal characteristics directly and indirectly and could adjust the temperature of the crop root zone.

Arsenic and mercury tolerant rhizobacteria that can improve phytoremediation of heavy metal contaminated soils.

Mining deposits often contain high levels of toxic elements such as mercury (Hg) and arsenic (As) representing strong environmental hazards. The purpose of this study was the isolation for plant growth promoting bacteria (PGPBs) that can improve phytoremediation of such mine waste deposits. We isolated native soil bacteria from the rhizosphere of plants of mine waste deposits and agricultural land that was previously mine tailings from Tlalpujahua Michoacán, Mexico, and were identified by their fatty acid profile according to the MIDI Sherlock system. Plant growth promoting traits of all bacterial isolates were examined including production of 3-indoleacetic acid (IAA), siderophores, biofilm formation, and phosphate solubilization. Finally, the response of selected bacteria to mercury and arsenic was examined an in-vitro assay. A total 99 bacterial strains were isolated and 48 identified, representing 34 species belonging to 23 genera. Sixty six percent of the isolates produced IAA of which Pseudomonas fluorescens TL97 produced the most. Herbaspirillum huttiense TL36 performed best in terms of phosphate solubilization and production of siderophores. In terms of biofilm formation, Bacillus atrophaeus TL76 was the best. Most of the bacteria isolates showed high level of tolerance to the arsenic (as HAsNa2O4 and AsNaO2), whereas most isolates were susceptible to HgCl2. Three of the selected bacteria with PGP traits Herbispirillum huttiense TL36, Klebsiella oxytoca TL49 and Rhizobium radiobacter TL52 were also tolerant to high concentrations of mercury chloride, this might could be used for restoring or phytoremediating the adverse environmental conditions present in mine waste deposits.

Characterizing Bacillus globigii as a Bacillus anthracis surrogate for wastewater treatment studies and bioaerosol emissions.

This study characterized Bacillus globigii (BG) as a Bacillus anthracis Sterne (BAS) surrogate for wastewater treatment-related studies of UV inactivation, adsorption onto powdered activated carbon (PAC), and bioaerosol emission. The inactivation of BG was faster than that of BAS in DI water (pseudo first-order rate constants of 0.065 and 0.016 min-1 respectively) and in PBS solution (0.030 and 0.005 min-1 respectively). BG was also removed more quickly than BAS by PAC adsorption in DI (0.07 and 0.05 min-1 respectively) and in PBS (0.09 and 0.04 min-1 respectively). In DI, BG aggregated more (P < 0.05) than BAS when the pH was 7 or greater but there were no statistically significant differences in NaCl solution. Spore aggregation was also studied with extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) models. Less than 1% of all spores were released as bioaerosols, and there was no significant difference (P > 0.05) in emission between BG and BAS. To the author's knowledge, this study is the first to demonstrate that BG is a suitable surrogate for BAS for bioaerosol emissions, but a poor surrogate for both UV inactivation and PAC adsorption. These results can be used to understand the ability of BAS to act as a surrogate for BA Ames because of its genetic and morphological similarities with BAS.

Millettia Pinnata leaves extract mediated ZnO nanoparticles and their antimicrobial, cytotoxicity study

Synthesizing ZnO nanoparticles for their antibacterial and cytotoxic properties is performed using a green concept in this study. Millettia Pinnata leaf extract was used to reduce zinc acetate to prepare ZnO nanoparticles. Due to the high concentration of biomolecules (flavonoids, alkaloids etc.,), Millettia Pinnata leaf extract produces stable ZnO nanoparticles. The structural and optical properties of ZnO nanoparticles have been investigated using UV–visible spectroscopy, X-ray diffraction spectroscopy, Fourier-transfer infrared spectroscopy, scanning electron microscopy, and X-ray energy dispersive spectroscopy. The prepared ZnO nanoparticles are spherical, have a hexagonal crystal phase, and are relatively stable. ZnO nanoparticles were tested for antibacterial and antifungal properties against Bacillus globigii, Escherichia coli and Aspergillus niger. The MTT assay measured the cytotoxic activity against the human breast cancer (MCF-7) cell lines. Its environmentally friendly properties suggest that the synthesized ZnO nanoparticles may be used in a wide variety of environmental remediation applications due to their antibacterial, antifungal, and anticancer properties.

Digital Twin for biological safety cabinet to reproduce performance and field certification test specified by NSF/ANSI 49 - 2019

The airflow balance test to confirm the physical performance of biological safety cabinets (BSC) is standardized by JIS K 3800 in accordance with NSF/ANSI 49 in Japan. In the test, Bacillus atrophaeus spores are used as an evaluation index, which poses a few limitations, such as their dependence on the environmental conditions to be tested. The aim of this study is to develop BSC digital twins and discuss reasonable alternatives for performance evaluation tests while maintaining the accuracy of the bacterial test performance. Herein, we provide the outline of a digital twin model for BSCs and the results of a numerical analysis, where a passive scalar is used as an alternative pollutant in the evaluation index.

A Simple Method for Generating Narrowly-dispersed Bioaerosols in Various Sizes

Biological warfare agents (BWAs) cause disease in humans, animals, and plants when purposefully dispersed in an area. To minimize contamination and personnel exposure and initiate early treatment, effective BWA detection or monitoring techniques are needed. Currently, bioaerosol detection or monitoring techniques are used for detecting BWA; however, these techniques have limitations, such as limited sensitivity. To improve the detection performance and develop novel techniques, an additional step in sample preparation, such as obtaining particles of various sizes, is needed. In this study, we investigated the simple and effective generation of bioaerosol particles using a custom-made inkjet aerosol generator (IJAG). Unlike previous inkjet aerosol generators, the operation conditions of the IJAG are fixed at a nozzle heating temperature of 140°C, a driver voltage of 150 V, a pulse width of 60 µs, and a frequency of 250 Hz. The only controlled factor was the concentration of bioaerosol models, including Bacillus globigii spores, ovalbumin, and polystyrene sphere latex. Our system generated bioaerosols with a diameter of 1–8 µm and a narrow distribution size. These results suggest that our IJAG system can achieve the simple and versatile generation of narrow-dispersed bioaerosols for a wide range of available materials. Our study can help improve the sensitivity of detection and monitoring systems for BWAs and bioaerosols.

Чувствительность агрономически-ценных штаммов р. Bacillus к лиофилизации

The effect of lyophilization with the use of lyoprotective substrates and without lyoprotectors on the survival of endospores of two strains of Bacillus spp., prospective as biological agents for the protection of agricultural plants from a complex of fungal diseases, was studied. Without the use of lyoprotectors, the survival rate of endospores after lyophilization of the strain B. atrophaeus RSA-1 was 61.2%, of the strain B. subtilis RSA-20(2) – 47.6%. Faibich's protective substrate statistically significantly increased the proportion of surviving endospores of the B. atrophaeus RSA-1 strain by 1.46 times, but did not lead to an increase in the proportion of surviving endospores of the strain B. subtilis RSA-20(2). The use of peptone-sucrose-glycerin mixture did not lead to a statistically significant increase in the proportion of survivors of endospore lyophilization in both strains. The injection of ascorbic acid as an antioxidant into the protective substrate of Faibich led to a statistically significant decrease in the proportion of surviving endospores in comparison with the version without lyoprotectors (1.6 times for the strain B. atrophaeus RSA-1 and 25 times for the strain B. subtilis RSA-20(2)). Keywords: BIOLOGICAL PROTECTION OF PLANTS FROM DISEASES, ANTAGONIST STRAINS, BACILLUS ATROPHAEUS, BACILLUS SUBTILIS, LYOPHILIZATION, LYOPROTECTIVE SUBSTRATE

Geobacillus stearothermophilusandBacillus atrophaeusspores exhibit linear inactivation kinetic performance when treated with an industrial scale vaporized hydrogen peroxide (VH2O2) sterilization process

This study aims to determine the inactivation kinetics of Geobacillus stearothermophilus and Bacillus atrophaeus biological indicators, treated with vaporized hydrogen peroxide (VH2O2) at an industrial scale. There is an assumption that sterilization processes generate linear kinetic plots of treated biological indicators that are used for informing probability-based decision-making by the MedTech industry for effective sterilization treatments; however, this has not been reported for sterilization using VH2O2. Survivor curves were generated, and sterilization performances were separately determined using G. stearothermophilus and B. atrophaeus biological indicators following the development of appropriate process challenge devices (PCDs). Regression analysis revealed that the inactivation kinetics for VH2O2-treated microorganisms exhibited log linear profiles. The use of scanning electron microscope (SEM) revealed no significant topographical changes in the outer surface of these VH2O2-treated spores. Both biological indicators exhibited log linear inactivation kinetics when treated with an industrial scale vaporized hydrogen peroxide (VH2O2) sterilization process. Therefore, this novel finding corroborates and proves the appropriateness of using VH2O2 as a sterilization method in accordance with applicable ISO standards.