Bacillus Atrophaeus Research Articles

Pharmacological potential of seaweed-associated heterotrophic bacterium Bacillus atrophaeus.

Extremities in marine environmental conditions led the marine macroalga-associated bacteria to adapt and biosynthesize potential bioactive agents. The myriad of marine macroalgae and the bacterial flora they are associated with constitute a potential source of bioactive components with significant biotechnological and pharmacological applications. Heterotrophic bacteria associated with the intertidal macroalgae were isolated and assessed for their pharmacological properties. Subsequently, Firmicutes dominated more than half of the 152 cultivable isolates from macroalgae-associated bacteria collected from the Gulf of Mannar (9°17'0'' N, 79°7'0'' E), on Peninsular India's southern coast. A total of 43 of those demonstrated steady antibacterial activities against a wide range of nosocomial pathogens. Among the bacteria isolated from marine macroalgae, Bacillus atrophaeus SHB2097 (MW821482) exhibited significant antimicrobial activities against clinically important pathogens. Organic extract of B. atrophaeus SHB2097 showed potential antimicrobial activities against test pathogens (minimum inhibitory concentration 6.25µg/mL). Organic extract of B. atrophaeus SHB2097 revealed promising inhibition potential against cyclooxygenase-2 (IC90 53.26µg/mL) and 5-lipoxygenase (IC90 9.74µg/mL). The carbolytic enzyme α-glucosidase inhibition potential of the organic extract of the studied heterotrophic bacterium was significantly greater than (IC90 118µg/mL) than that displayed by acarbose (IC90 645µg/mL, p < 0.05). The significance of nuclear magnetic resonance-centered analyses of distinguishing signals in the organic extract and correlating those with bioactive potential was accentuated. The utilities of nuclear magnetic resonance-based fingerprinting emphasized the assessment of the distinctive signals in the solvent extracts and their correlation with the pharmacological properties. Thus, the heterotrophic B. atrophaeus SHB2097 could be used to develop potential therapeutic and biomedical agents.

Growth, development and thermal resistance of Bacillus atrophaeus spores using whey culture media

Whey represents an important environmental problem for the dairy industry due to its high volume and organic load. Studies that evaluate new forms of use of these residues such as growth medium for microorganisms, can help to develop a better destination providing an added value bioproduct. This work aims to evaluate the development of Bacillus atrophaeus spores ATCC 9372 growing in whey culture media to determine the reuse of this dairy residue. Whey at a concentration varying from 1.0g. L-1 to 20.0g. L-1 was dissolved into water and Bacillus atrophaeus spores were incubated for 6 days. Thermal treatments were performed at 102oC and 104oC and in all conditions evaluated, the decay of spores population was linear. In solid media, D-values at 102oC ranged from 1.24 min to 2.98 min and at 104oC ranged from 1.27 min to 2.35 min. The culture media containing whey can enable the growth and sporulation of Bacillus atrophaeus. This study confirms the possibility of using this dairy industry residue as an alternative to obtain bacterial spores, which may be used in validation of thermal.

Bacillamide F, Extracted from Marine Bacillus atrophaeus C89, Preliminary Effects on Leukemia Cell Lines.

Developing new treatments for leukemia is essential since current therapies often suffer from drug resistance and toxicity. Bacillamides are very promising, naturally occurring compounds with various bioactivities. In the present study, we investigated the use of bacillamide analogues, a new thiazole alkaloid bacillamide F that was isolated from marine Bacillus atrophaeus C89 associated with sponge Dysidea avara. The structure of the new compound bacillamide F with indolyl-thiazolyl-pyrrolidine ring was determined by high resolution mass spectrometry, secondary mass spectrometry, and nuclear magnetic resonance analyses. Intriguingly, bacillamide F is able to inhibit the proliferation of an acute myeloid leukemia cell line HL60 (IC50 (24 h) 21.82 µM), and an acute T-cell leukemia Jurkat (IC50 (24 h) 46.90 µM), rather than inhibit the proliferation of the acute histiocytic lymphoma U-937 cell line, human fetal lung fibroblast MRC-5 cell line, and some solid tumor cell lines (IC50 (24 h) &gt; 100 µM). The study provides a new indication of the pharmacological activity of natural product bacillamides.

Effectiveness of formaldehyde in various soil types as a wide area decontamination approach for Bacillus anthracis spores.

The purpose of this study was to evaluate and compare the decontamination efficacy of liquid formaldehyde solutions for three soil types (sand, loam, and clay) against spores of Bacillus anthracis (B.a.) and Bacillus atrophaeus. Approximately 1 x 108 colony forming units were inoculated into each sample. Through a series of six bench-scale experiments, two concentrations and two volumes of liquid formaldehyde solution were then added to the soil samples and allowed to remain in contact for either 24 or 48 hours. Decontamination efficacy was assessed at either 22° or 10°C with or without lids atop the sample jars. Complete inactivation (no spores recovered from the soil samples, typically providing > 7 log reduction) of B.a. occurred in all soil types in five of the six tests, while complete inactivation of B. atrophaeus was achieved in all soil types for three of the six tests. The results demonstrated a higher probability of complete inactivation of spores for samples that were covered, samples that received the higher volume of formaldehyde, and those contaminated with B.a. Overall, the use of liquid formaldehyde solution (2.5-5%) was highly effective in inactivating entire spore populations (typically > 107 CFU) for both B.a. and B. atrophaeus in the soil matrices studied. Covering the soil after application would allow for less formaldehyde solution to be used without impacting the overall efficacy of the process. The data from this study may aid in the selection of appropriate decontamination parameters when using liquid formaldehyde for soil remediation. The data may also aid in the decision to use B. atrophaeus as a surrogate for B.a. when performing further decontamination studies using liquid formalin solutions.

Application of 3D-Woven Fabrics for Packaging Materials for Terminally Sterilized Medical Devices.

This research aimed to test a newly developed 3D fabric for use in a hospital sterilization unit as a packaging material. Two basic properties were tested: the efficiency of the microbial barrier, and the bursting strength of the woven fabric, determined with a steel ball. Material deformations caused by bursting are common in medical sterilization, as a consequence of the packaging of the medical tools needed in surgery. Six 3D-fabric samples were woven from the same warp, with three weft densities and in two different weaves. The weaving conditions and other construction characteristics of the fabrics were the same. To determine the effectiveness of the microbial barrier, bacterial endospores of an apathogenic species of the genus Bacillus, Geobacillus stearothermophilus and Bacillus atrophaeus, were used. Mechanical testing of the 3D-woven fabric, i.e., the bursting strength of the fabric using a steel ball, was carried out according to the standard method. The results showed the exceptional puncture strength of the woven fabrics and their formation of an effective microbial barrier, i.e., complete impermeability to microorganisms in five samples, which is the main condition for possible use as a packaging material in medical sterilization. Sample 3tp did not provide an effective microbial barrier and did not meet the basic requirements for use in medical sterilization.

Comparison of one-step with two-step production of Bacillus atrophaeus spores for use as bioindicators.

The production method of spores significantly influences the resistance of spores used as bioindicators (BI) in the validation of sterilization of packaging material surfaces in aseptic food manufacturing. Therefore, the standardization of the spore production method represents an important and desirable goal in industrial BI production to ensure reliable validation test results. Previously, we recommended a two-step production approach for submerged spore production, in which the cultivation phase to obtain high cell mass was separate from the sporulation phase. In this work, a one-step manufacturing process was investigated to reduce production complexity and facilitate standardization of spore production. It was found that one-step BI production is technically possible but at the expense of spore yield. The two-step manufacturing process can realize almost 10-fold higher spore yields.

Comparative Assessment of Pulsed and Continuous LED UV-A Lighting for Disinfection of Contaminated Surfaces

The germicidal efficacy of LED UV-A lighting has scarcely been compared in continuous and pulsed modes for contaminated surfaces. Herein, we compare the disinfection properties of pulsed versus continuous lighting at equal irradiances using a 365 nm LED device that replicates the doses of occupied-space continuous disinfection UV-A products. Representative organisms evaluated in this study included human-infectious enveloped and non-enveloped viruses (lentivirus and adeno-associated virus, respectively), a bacterial endospore (Bacillus atrophaeus), and a resilient gram-positive bacterium (Enterococcus faecalis). Nominal UV-A irradiances were tested at or below the UL standard limit for continuous human exposure (maximum irradiance of 10 W/m2). We observed photoinactivation properties that varied by organism type, with bacteria and enveloped virus being more susceptible to UV-A than non-enveloped virus and spores. Overall, we conclude that continuous-mode UV-A lighting is better suited for occupied-space disinfection than pulsing UV-A at equivalent low irradiances, and we draw comparisons to other studies in the literature.

Bacillus spp.-Mediated Growth Promotion of Rice Seedlings and Suppression of Bacterial Blight Disease under Greenhouse Conditions.

Rice (Oryza sativa L.) is a major cereal and staple food crop worldwide, and its growth and production are affected by several fungal and bacterial phytopathogens. Bacterial blight (BB) is one of the world's most devastating rice diseases, caused by Xanthomonas oryzae pv. oryzae (Xoo). In the current study, Bacillus atrophaeus FA12 and B. cabrialesii FA26 were isolated from the rice rhizosphere and characterized as having broad-range antifungal and antibacterial activities against various phytopathogens, including Xoo. In addition, the selected strains were further evaluated for their potent rice growth promotion and suppression efficacy against BB under greenhouse conditions. The result shows that FA12 and FA26, applied as seed inoculants, significantly enhanced the vigor index of rice seedlings by 78.89% and 108.70%, respectively. Suppression efficacy against BB disease by FA12 and FA26 reached up to 59.74% and 54.70%, respectively, in pot experiments. Furthermore, MALDI-TOF MS analysis of selected strains revealed the masses ranged from m/z 1040 to 1540, representing that iturins and fengycin are the major antimicrobial compounds in the crude extracts, which might have beneficial roles in rice defence responses against BB. In conclusion, FA12 and FA26 possess broad-range antagonistic activity and have the capability to promote plant growth traits. More importantly, applying these strains has a high potential for implementing eco-friendly, cost-effective, and sustainable management practices for BB disease.

Direct Observation of the Sporicidal Action of Hydrogen Peroxide on Bacillus atrophaeus Spores By Optical Trapping Raman Microscopy

Hydrogen peroxide (H2O2), a strong oxidizer, is frequently used for chemical sterilization in aseptic food processing. Due to their inherent robustness, bacterial spores, i.e. spores of Bacillus atrophaeus, are commonly employed to evaluate the efficacy of the sterilization procedure [1]. Despite its widespread use, however, the details of the sporicidal action of H2O2 are not yet fully understood, with various mechanisms being discussed in the literature [2,3]. Here, we employ optical trapping Raman microscopy to elucidate the sporicidal mechanism of H2O2. Optical trapping Raman microscopy allows us to isolate, investigate, and manipulate individual spores from a sample (Fig. 1A). Combining optical microscopy with the real-time, label-free chemical information obtained from Raman spectroscopy directly reveals the sequence of steps that lead to oxidative spore death after H2O2 exposure (Fig. 1B).We find that spore degradation begins with the fast, cooperative release of dipicolinic acid (DPA), a key spore biomarker and a major component of spore’s core. This indicates a breach of the inner membrane surrounding the core. The onset of DPA release depends on the concentration of H2O2. DPA outflux is accompanied by the formation of oxidation products (mostly carbonyl compounds) and oxidation continues after exchange of DPA with the surrounding medium is complete. The remaining spore shell then slowly disintegrates and continues to shrink on a timescale of hundreds of seconds. Simultaneous observation of spore morphology and size by optical microscopy and particle tracking corroborates this three-step mechanism.The presented assay allows on-line monitoring of spore composition and morphology, which directly reveals the mechanism underlying the sporicidal action of H2O2. In addition, trapped spores can be exposed to different chemical or physical stimuli (temperature, light, chemical composition of the surrounding medium, etc.) to investigate a variety of industrially relevant sterilization conditions. Jildeh, Z. B., Wagner, P. H. & Schöning, M. J. Sterilization of Objects, Products, and Packaging Surfaces and Their Characterization in Different Fields of Industry: The Status in 2020. physica status solidi (a) 218, 2000732 (2021). Setlow, P. & Christie, G. What’s new and notable in bacterial spore killing. World J Microbiol Biotechnol 37, 144 (2021). Setlow, P. Spores of Bacillus subtilis: their resistance to and killing by radiation, heat and chemicals. J Appl Microbiol 101, 514-525 (2006). Figure 1

Inactivation kinetics of Bacillus atrophaeus in liquid hydrogen peroxide for aseptic package sterilization

Liquid hydrogen peroxide is used as a common sterilant for the aseptic packaging materials. Based on the Food Safety Objective (FSO) for specific products, a surrogate organism, Bacillus atrophaeus, is used to validate the sterilization processes. This study aims to develop a methodology for the kinetic inactivation parameter estimation of B. atrophaeus. Spores of B. atrophaeus were challenged with various peroxide concentrations (20%, 28%, and 33%; v/v) and temperatures such as 23, 55, 71.1, and 82.2 °C. The log-linear and Weibull models were used for the inactivation models for liquid peroxide at different temperatures. The parameters were estimated at a reference temperature of 80 °C for log-linear and Weibull models. With peroxide concentrations of 20, 28, and 33%, the log-linear model estimated D values were 0.95, 0.47, and 0.08 min and z values were 94.67, 86.86, and 41 °C, respectively. The Weibull model δ values were 0.31, 0.23, and 0.05 min with a z value of 85.18, 81.23, and 41.39 °C for 20, 28, and 33% peroxide, respectively. The RMSE values varied from 0.60 to 0.79 log CFU/ml, the sum of the squares was between 27.3 and 39.7, and the parameters' relative errors were less than 6%.

Persistence of surrogates for high consequence viral and bacterial pathogens in a pilot-scale activated sludge treatment system.

The persistence of high consequence public health pathogens in a wastewater treatment system can significantly impact worker safety, as well as the public and downstream water bodies, particularly if the system is forced to shut down the treatment processes. This study utilizes organism viability to compare the persistence of three pathogen surrogates in wastewater using a pilot-scale activated sludge treatment (AST) system, operated to mimic treatment processes of large-scale plants. Bacillus globigii spores, surrogate for Bacillus anthracis, persisted in the AST system for at least a 50-day observation period leading to a possible steady condition far beyond the solid retention time for sludge particles. MS2 bacteriophage, surrogate for Poliovirus and other non-enveloped enteric viruses, was observed for up to 35 days after introduction, which largely and expectedly correlated to the measured solid retention time. Phi-6 bacteriophage, a surrogate for Ebola virus and other enveloped viruses, was detected for no more than 4 days after introduction, even though the AST system was operated to provide three times slower solids removal than for the other surrogates. This suggests Phi-6 is subject to inactivation under AST conditions rather than physical removal. These results may suggest similar persistence for the surrogated pathogens, leading to appropriate consequence management actions.

Interaction of a natural compound nanoemulsion with Gram negative and Gram positive bacterial membrane; a mechanism based study using a microfluidic chip and DESI technique

The antibacterial activity of a nanoemulsion prepared from Satureja Khusitanica essential oil against a Gram-negative (Escherichia coli) and a Gram-positive (Bacillus atrophaeus) bacteria evaluated using microfluidic and conventional techniques. The effect of different residence time and concentrations on the antibacterial activity of nanoemulsion was studied by measuring the release of protein, nucleic acids, potassium, and also recording the MIC, MBC and time killing assays. Remarkable intensification was observed by employing microfluidic chip regarding a high-contact surface area between nanodroplets and bacterial membrane. The MIC and MBC values for E. coli and B. atrophaeus in conventional method were 400 and 1600 µg mL−1, respectively, whereas these values reduced to 11 to 50 µg mL−1 using microfluidic system. B. atrophaeus seemed to be more resistant than E. coli to the nanoemulsion treatment, perhaps due to different cell wall structures. Bacterial cell wall changes were examined using a desorption electrospray ionization (DESI) technique. It was found that the structural changes were more imminent in Gram negative E. coli by detecting a number of released lipids including phosphatidyl glycerol and phosphatidyl ethanolamines. The DESI spectra of B. atrophaeus revealed no M/Z related lipid release. These findings may help providing novel nano based natural antibacterials.

Incorporation of Ambient Water-H into the C-Bonded H Pool of Bacteria during Substrate-Specific Metabolism

The stable isotope ratios of C-bonded H (δ2Hn values) can be used to locate soil samples for forensic purposes because of their close correlation with the δ2H values of precipitation. Post-sampling bacterial activity might change the δ2Hn values via glycolysis. We tested to which degree C-bonded H is replaced by H from ambient water under favorable and unfavorable growing conditions. We provided two heterotrophic bacteria (Bacillus atrophaeus, Escherichia coli) with glucose (favorable) or lysine (unfavorable) under aerobic conditions. We assessed the H incorporation from ambient water via 2H labeling. We found that the H incorporation into bacterial biomass in the glucose treatment was 79 ± 5.9% (B. atrophaeus) and 43 ± 3.0% (E. coli), likely as a consequence of glycolysis and conservation of the δ2H value in the anabolic mode of the tricarboxylic acid (TCA) cycle. Differences between species were possibly related with different compositions of metabolite mixtures. The bacteria did hardly grow with lysine while respiration continued, and we found no H incorporation because the catabolic mode of the TCA cycle, which was active when the bacteria grew on lysine, is associated with CO2 release and a complete cleavage of former C–2H bonds. Our results support the glycolysis pathway as a mechanism underlying the incorporation of ambient-water H into the C-bonded H pool of bacteria. Stressful conditions forcing bacteria into a catabolism-dominated metabolism disable the incorporation of ambient-water H, and δ2Hn values can be applied to identify the origin of soil samples in forensics.

Disinfection of an ambulance using a compact atmospheric plasma device.

The worldwide spread of the coronavirus SARS-CoV-2 has highlighted the need for fast and simple disinfection processes, amongst others for ambulance cars on site. To overcome current drawbacks regarding room disinfection, the use of cold atmospheric plasma in remote operation represents a promising alternative for the disinfection of larger volumes. In this study, a compact plasma system was evaluated regarding its disinfection efficiency inside an ambulance car. The developed plasma device is based on a dielectric barrier discharge (DBD) and operates with ambient air as process gas. The humidified afterglow from the plasma nozzle was introduced into an ambulance car with a volume of approximately 10 m3 while Bacillus atrophaeus endospores, Staphylococcus aureus or Phi 6 bacteriophages dried on different surfaces (PET-films, glass slides or aluminum foil) were exposed to the reactive gas inside the ambulance vehicle at eight different positions. Reductions of spores by more than 4 orders of magnitude were found on all surfaces and positions within 2 h. Due to their higher susceptibility, Phi 6 bacteriophages and S. aureus counts were reduced by at least 4 orders of magnitude within 30 min on all surfaces. The results show that different microorganisms dried on variable surfaces can be inactivated by several orders of magnitude inside an ambulance by plasma gas from of a compact DBD plasma nozzle. Plasma gas generated on site by a DBD plasma nozzle proved to be highly efficient for the disinfection of the interior of an ambulance car. Compact plasma systems could be a viable alternative for the disinfection of vehicles or rooms.

Secretion of poly-γ-glutamic acid by Bacillus atrophaeus NX-12 enhanced its root colonization and biocontrol activity.

Bacilli are used as biocontrol agents (BCAs) against phytopathogens and most of them can produce poly-γ-glutamic acid (γ-PGA) as one of the major extracellular polymeric substances (EPSs). However, the role of γ-PGA in plant biocontrol is still unclear. In this study, Bacillus atrophaeus NX-12 (γ-PGA yield: 16.8 g/l) was screened, which formed a strong biofilm and has been proved to be a promising BCA against Cucumber Fusarium wilt. Then, the γ-PGA synthesis gene cluster pgsBCA was knocked out by CRISPR-Cas9n. Interestingly, the antifungal ability of γ-PGA synthetase-deficient strain NX-12Δpgs (γ-PGA yield: 1.65 g/l) was improved in vitro, while the biocontrol ability of NX-12Δpgs was greatly diminished in situ. Data proved that γ-PGA produced by NX-12 contributes to the biofilm formation and rhizosphere colonization, which effectively improved biocontrol capability. Taken together, these findings prove that the mechanism of γ-PGA promotes the colonization of NX-12 and thus assists in controlling plant diseases, which highlight the key role of γ-PGA produced by BCA in biocontrol.

Improving Degradation of Polycyclic Aromatic Hydrocarbons by Bacillus atrophaeus Laccase Fused with Vitreoscilla Hemoglobin and a Novel Strong Promoter Replacement.

Simple SummaryPolycyclic aromatic hydrocarbons (PAHs) are a large group of persistent organic pollutant chemicals that have significant carcinogenic effects on humans and animals. Degradation of PAHs by microbial laccase is a low-cost and high-efficiency pipeline, but the catalytic activity and expression level for most of the native bacterial laccases are low, limiting their wide use in industry. A recombinant enzyme called LacH5 showed high-efficiency PAH degradation activity, and its degradation activity was further improved by fusion expression and the expression level was augmented by a novel strong promoter replacement. The results from the current investigation provide new insights and strategies for PAH degradation and the development of a new candidate laccase for PAH biodegradation.Laccases catalyze a variety of electron-rich substrates by reducing O2 to H2O, with O2 playing a vital role as the final electron acceptor in the reaction process. In the present study, a laccase gene, lach5, was identified from Bacillus atrophaeus through sequence-based screening. LacH5 was engineered for modification by fusion expression and promoter replacement. Results showed that the purified enzyme LacH5 exhibited strong oxidative activity towards 2,2’-azinobis(3-ehtylbenzothiazolin-6-sulfnic acid) ammonium salt (ABTS) under optimum pH and temperature conditions (pH 5.0, 60 °C) and displayed remarkable thermostability. The activity of the two fusion enzymes was enhanced significantly from 14.2 U/mg (LacH5) to 22.5 U/mg (LacH5-vgb) and 18.6 U/mg (Vgb-lacH5) toward ABTS after LacH5 fusing with Vitreoscilla hemoglobin (VHb). Three of six tested polycyclic aromatic hydrocarbons (PAHs) were significantly oxidized by two fusion laccases as compared with LacH5. More importantly, the expression level of LacH5 and fusion protein LacH5-vgb was augmented by 3.7-fold and 7.0-fold, respectively, by using a novel strong promoter replacement. The results from the current investigation provide new insights and strategies for improving the activity and expression level of bacterial laccases, and these strategies can be extended to other laccases and multicopper oxidases.

Maize growth response to different Bacillus strains isolated from a salt-marshland area under salinity stress

Maize (Zea mays) growth performance has been hindered due to the high soil salinity. Salinity is one of the most severe abiotic stresses that has led to growth imbalance and profitability of harvests in arid and semi-arid regions. Plants have taken advantage of salt-tolerant bacteria as plant growth-promoters to enhance growth and reduce the adverse effects of salinity through the regulation of some biochemical, physiological, and molecular features. Preferences for non-chemical, eco-friendly, and economical approaches have caused the inquiry of the Bacillus genus as a joint group of plant growth-promoting rhizobacteria known to alleviate salt-stress impacts. In the present study, halotolerant Bacillus strains were isolated from salt-marshland soil and characterized for their physiological, molecular, and biochemical properties. Twenty-four bacterial isolates collected from high saline fields of salt marshland were analyzed by MALDI-TOF MS proteome analysis, which confirmed the taxonomic affiliation with Bacillus cereus, Bacillus subtilis, Bacillus atrophaeus, and Bacillus thorngiensis. Applying the isolates on maize plants as bio-inoculant bacteria obviously increased the growth parameters (P < 0.01). Pot experiments showed that isolates 74 and 90 were the most prominent strains to minimize the harmful effects of salinity. Its effects are heightening the potassium/sodium ratio and K-Na selectivity in shoots and roots measured by flame atomic absorption photometry (AAS). Accordingly, Bacillus cereus isolate 74 showed a maximum increase in dry weights of the shoot (133.89%), root (237.08%), length of the shoot (125%), and root (119.44%) compared to the control condition. Our findings suggest that bacteria isolated from marshland may be an economical and simple means to increase plant growth and resistance to high salinity soil conditions.

Effective inactivation of Bacillus atrophaeus spores and Escherichia coli on disposable face masks using ultraviolet laser irradiation

Due to the widespread emergence of COVID-19, face masks have become a common tool for reducing transmission risk between people, increasing the need for sterilization methods against mask-contaminated microorganisms. In this study, we measured the efficacy of ultraviolet (UV) laser irradiation (266 nm) as a sterilization technique against Bacillus atrophaeus spores and Escherichia coli on three different types of face mask. The UV laser source demonstrated high penetration of inner mask layers, inactivating microorganisms in a short time while maintaining the particle filtration efficiency of the masks. This study demonstrates that UV laser irradiation is an efficient sterilization method for removing pathogens from face masks.

Combined effect of Debaryomyces hansenii and Bacillus atrophaeus on the physicochemical attributes, defense-related enzyme activity, and transcriptomic profile of stored litchi fruit

Postharvest disease and peel browning are critical problems in the storage and transportation of litchi fruit. Our previous studies demonstrated that either Debaryomyces hansenii (Y-1) or Bacillus atrophaeus (TE-7) used individually significantly reduced postharvest diseases in mango fruit. The combined postharvest use of Y-1 and TE-7 on litchi fruit (Litchi chinensis), however, has not been investigated. In the present study, the effect of the combined use of Y-1 and TE-7 on the disease index, physicochemical attributes, defense-related enzyme activity, and the transcriptomic profile of litchi fruit stored at 25 ℃ were investigated. Results demonstrated that the combined use of Y-1 and TE-7 (Y-TE) lowered the browning index (BI) and disease index (DI), inhibited weight loss (WL), reduced electrolyte leakage (EL) and the level of malondialdehyde (MDA) in stored litchi fruit. Y-TE-treated fruit maintained a significantly higher level of total soluble solids (TSS), titratable acidity (TA), and vitamin C (Vc), compared to untreated, control fruit, and also enhanced peroxidase (POD) and superoxide dismutase (SOD) activity. In addition, RNA-seq analysis of the transcriptome of treated and untreated fruit revealed that the Y-TE treatment modulated several metabolic pathways, including those involved in plant-hormone signal transduction and plant-pathogen interaction. RT-qPCR analysis indicated that the expression level of LcAUX28, LcAUX1, LcARF1, LcRD19A, and LcWRKY1 were significantly up-regulated in stored litchi fruit by the Y-TE treatment. Collectively, these findings provide a greater understanding of how Y-TE prevents disease and maintains the quality of stored litchi fruit. The combined use of these biocontrol agents represents a new strategy for managing postharvest diseases and preserving the postharvest quality of litchi fruit during storage and transportation.

Влияние средства защиты растений на основе Bаcillus atrophaeus ВКПМ В-11474 на агрономические характеристики бахчевых культур в Астраханской области

The Astrakhan region is the main vegetable-growing and melon-growing center of Russia, characterized by favorable agro–climatic conditions for growing vegetable and gourd crops. The agro-climatic conditions of the region make it possible to obtain the earliest, highest and most stable yields. Currently, in the southern regions, the problem of reducing the use of mineral fertilizers and pesticides in agriculture with their replacement by biological methods &#x0D; of plant protection is quite acute. Biological methods, in comparison with chemical means of protection, are distinguished by the selectivity of impact and by the environmental safety. Preliminary studies have shown that the studied laboratory sample of the agent based on Bacillus atrophaeus B‐11474 has pronounced fungistatic and growth-stimulating activities, which were confirmed by the field research results. The studied laboratory sample of the agent had a positive effect on the germination, development and biometric parameters of watermelon. The sample helped to increase productivity, reduce anthracnose, improve the qualitative and quantitative indicators of the cultivated crop. The prospects for using the triple treatment (spraying the bottom of the furrow and double spillage under the root of the plant with a laboratory sample of the agent have been established. In general, the use of a biological agent in the cultivation of watermelon in the fields of the Astrakhan region will make it possible to obtain environmentally friendly and safe products.