Bacilli Isolated Research Articles

Synergistic Antibacterial and Antibiofilm Effects of Clindamycin and Zinc Oxide Nanoparticles Against Pathogenic Oral Bacillus Species

Oral bacterial pathogens, including Bacillus species, form biofilms that enhance antibiotic resistance, promote bacterial adherence, and maintain structural integrity. The ability of bacteria to form biofilms is directly linked to several oral diseases, including gingivitis, dental caries, periodontitis, periapical periodontitis, and peri-implantitis. These biofilms act as a predisposing factor for such infections. Nanoparticles, known for their strong antibacterial properties, can target specific biofilm-forming microorganisms without disturbing the normal microflora of the oral cavity. This study focuses on the biofilm-forming ability and clindamycin (CM) resistance of Bacillus species found in the oral cavity. It aims to evaluate the antibacterial and antibiofilm properties of zinc oxide nanoparticles (ZnO-NPs) against oral Bacillus species and assess the effectiveness of combining CM with ZnO-NPs in reducing antibiotic resistance. The antibacterial susceptibility of Bacillus isolates was tested using ZnO-NPs and CM, demonstrating synergistic effects that reduced the minimum inhibitory concentrations by up to 8-fold. The fractional inhibitory concentration (FIC) index indicated a significant synergistic effect in most strains, with FIC values ranging from 0.375 to 0.5. It was found that the majority of Bacillus strains exhibited significant biofilm-forming capabilities, which were reduced when treated with the ZnO-NPs and CM combination. The study also evaluated the cytotoxicity of ZnO-NPs on cancer cells (CAL27) and normal fibroblasts (HFB4). CAL27 cells showed stronger cytotoxicity, with an IC50 of 52.15 µg/mL, compared to HFB4 cells, which had an IC50 of 36.3 µg/mL. Genetic analysis revealed the presence of biofilm-associated genes such as sipW and tasA, along with antibiotic resistance genes (ermC), which correlated with the observed biofilm phenotypes. Overall, this study demonstrates the potential of combining ZnO-NPs with CM to overcome antibiotic resistance and biofilm formation in the oral bacterial pathogens, Bacillus species. These findings suggest new approaches for developing more effective dental treatments targeting oral biofilm-associated infections and antibiotic resistance.

Isolation and safety evaluation of food-derived potential probiotic Bacillus with antimicrobial properties

Isolation and safety evaluation of food-derived potential probiotic Bacillus with antimicrobial properties

Batch fermentation and GC-MS analysis of biocontrol agent, Bacillus amyloliquefaciens strain KSAS6 and its impact on soilborne fungus, Sclerotium bataticola

Background: Sclerotium bataticola, a soil-born fungus, is responsible for charcoal rot in a variety of plants. It is also responsible for causing substantial damage to a wide range of horticultural crops around the world.Methods: Fifteen different Bacillus isolates were isolated and evaluated for their ability to inhibit S. batatacola's growth. The promising bacterial isolate was molecularly identified using NCBI-Blast and phylogenetic tree analysis of the 16S rRNA gene. Batch fermentation was performed in a stirred tank bioreactor to maximize culture biomass and secondary metabolite synthesis. Gas chromatography-mass spectrometry was used to discover secondary metabolite compounds.Results: The KSAS6 isolate was the most effective for inhibiting the fungal growth of mycelial cells, with a 48.2% inhibition percentage. The probable biocontrol agent, B. amyloliquefaciens strain KSAS6, was identified and recorded in GenBank under the accession number PQ271636. The culture biomass and secondary metabolites were maximized by the batch fermentation technique, reaching the highest achievable level of 2.1 g L-1 at 11 hours. This was accomplished while maintaining a steady specific growth rate (µ) of 0.13 h-1. Based on the observations, the biomass yield coefficient was found to be 0.37 g cells/g glucose. Among the 21 secondary metabolite compounds identified in GC-MS analysis, diisooctyl phthalate was the highest compound (43.31%).Conclusion: The strain of rhizobacterium B. amyloliquefaciens known as KSAS6 can inhibit the growth of S. bataticola, which makes it a promising candidate for the biocontrol of fungal infections in plants.Keywords: Sclerotium bataticola; Bacillus amyloliquefaciens; Batch fermentation; Secondary metabolites; antifungal

Effective Applications of Bacillus subtilis and B. amyloliquefaciens as Biocontrol Agents of Damping-Off Disease and Biostimulation of Tomato Plants

Using Bacillus species as bioagents for environmentally sustainable and economically viable plant disease management is a viable strategy. Thus, it is important to promote their use in agriculture. In this study, two Bacillus species were isolated from the rhizosphere of tomato plants, while three fungal species were isolated from samples of tomato plants that were infected with damping-off disease. The Bacillus strains were tested in vitro for their antagonistic activity against fungal species using a dual culture technique. In a greenhouse experiment, the effectiveness of applying antagonistic bacteria with soilborne fungal disease on induced damping-off of tomato (cv. Super Strain B) plants, their physiological attributes, antioxidant enzymes, mineral content, and yield under greenhouse conditions during the 2022 and 2023 seasons were determined. The fungal isolates were identified as Fusarium oxysporum KT224063, Pythium debaryanum OP823136, and Rhizoctonia solani OP823124, while the Bacillus isolates were identified as B. subtilis OP823140 and B. amyloliquefaciens OP823147 on the basis of the rRNA gene sequences. The dual culture test revealed that B. subtilis outperformed B. amyloliquefaciens in resistance to R. solani and F. oxysporum, which were recorded as 28.33 and 33.00 mm, respectivley. In contrast, B. amyloliquefaciens caused the highest antagonistic effect against tested P. debaryanum fungus. Additionally, in a greenhouse experiment, tomato plants treated with each of these antagonistic Bacillus strains significantly suppressed fungal disease, displayed improved plant growth parameters, had an increased content of photosynthetic pigments, antioxidants enzymes, and total phenols, and an increased macronutrient content and yield during the two growing seasons. In conclusion, effective applications of B. subtilis and B. amyloliquefaciens had the potential to mitigate damping-off disease, which is caused by F. oxysporum, P. debaryanum, and R. solani in tomato plants, while simultaneously promoting growth dynamics.

Potential of plant growth promoting rhizobacteria for enhancement of tomato growth

AbstractPlant growth‐promoting rhizobacteria (PGPR) associated with roots produce several biomolecules that stimulate plant growth. The study aimed to assess the potential of PGPR for tomato (Solanum lycopersicum L.) growth enhancement. Three PGPR isolates (Pseudomonas isolates PIA2 and PIA3, and Bacillus isolate BIA1) were evaluated for growth promotion under greenhouse conditions. The experiment was conducted in three replications using Maya and Melkesalsa tomato varieties in a completely randomized design. Treatment with BIA1 resulted in the highest fresh weights of shoots (29.05 g) and roots (3.72 g) for the Maya variety (TC1) and 28.69 and 2.76 g for the Melkesalsa variety (TC2), respectively. Treatment with PIA2 showed maximum fresh weights of the shoots (25.05 g) and roots (3.26 g) for the TC2. Tomato plants treated with BIA1 and PIA2 exhibited significant increases in height, by 40.1% and 22.6% in the TC1 and 45.2% and 27.6% in the TC2, respectively. Besides, treatments with BIA1 and PIA2 in the TC1 increased the dry weight of shoots by 46.6% and 30.2% and that of roots by 73.3% and 68.7%, respectively. For the TC2, BIA1 and PIA2 isolates increased the dry weight of roots by 54.9% and 34.4% and that of roots by 68.1% and 48.9%, respectively. The results generally showed that BIA1 and PIA2 could be used to foster plant growth. Further study under field the conditions of BIA1 and PIA2 are highly recommended.

Effect of sett bacterization on sugarcane seedlings under greenhouse conditions

Sugarcane being major a cash crop suffers with inappropriate fertilization practices and excessive pesticide usage which leads in increased costs for farmers and poses environmental and public health risks. Research and practical interventions are critical for maintaining sugarcane yields while minimizing environmental impacts. In this context the efficacy of 40 root-colonizing bacterial strains in promoting sugarcane seedling growth was evaluated under greenhouse conditions. Single-node setts of sugarcane cultivar 2009A 107 were inoculated with bacterial suspension (10-9 CFU ml-1) and subsequently sown in a cocopeat-vermicompost mixture. Germination percentage, shoot length, and seedling vigour index (SVI) were assessed at 40 days post-sowing. Several Bacillus and Pseudomonas isolates demonstrated significant enhancements in these growth parameters compared to the untreated control. Notably, four bacterial strains Bacillus inaquosorum strain SRB2, Bacillus vallismortis strain SRB20, Pseudomonas chlororaphis subsp. aurantiaca strain SRP19 and Pseudomonas aeruginosa strain SRP20, previously identified for their antagonistic properties, exhibited particularly strong positive effects on SVI. These findings suggest that sett bacterization with selected bacterial isolates can be a promising approach to improve sugarcane seedling establishment and vigour.

Microbial diversity and interactions: Synergistic effects and potential applications of Pseudomonas and Bacillus consortia.

Microbial diversity and interactions in the rhizosphere play a crucial role in plant health and ecosystem functioning. Among the myriads of rhizosphere microbes, Pseudomonas and Bacillus are prominent players known for their multifaceted functionalities and beneficial effects on plant growth. The molecular mechanism of interspecies interactions between natural isolates of Bacillus and Pseudomonas in medium conditions is well understood, but the interaction between the two in vivo remains unclear. This paper focuses on the possible synergies between Pseudomonas and Bacillus associated in practical applications (such as recruiting beneficial microbes, cross-feeding and niche complementarity), and looks forward to the application prospects of the consortium in agriculture, human health and bioremediation. Through in-depth understanding of the interactions between Pseudomonas and Bacillus as well as their application prospects in various fields, this study is expected to provide a new theoretical basis and practical guidance for promoting the research and application of rhizosphere microbes.

The Effects of Bio-Priming on Seed Germination and Seedling Growth of Italian Ryegrass (Lolium multiflorum Lam.)

Seed bio-priming applications with plant growth promoting rhizobacteria (PGPR) have been widely used recently to improve germination and seedling growth. Therefore, the aim of this study was to investigate the effects of bio-priming with different bacterial strains on germination and seedling development of Italian ryegrass seeds. The sterilized seeds of the Elif variety (Lolium multiflorum Lam) were inoculated with nine different bacterial strains belonging to Bacillus species (108 cfu/mL bacterial suspension) for 15 min at 120 rpm and then dried at room temperature. The treated seeds were germinated in petri dishes with 25 seeds between 3 filter papers at 22 ±2 ˚C. The study was carried out in a completely randomized design with three replications. As a result of the study, no significant difference was obtained between the treatments in germination percentage and root length, but it was determined that SY2 and SY5 (Bacillus isolates) showed superior performance compared to the control in terms of shoot length and seedling fresh and dry weights.

Bacillus endophytes for sustainable management of tomato spotted wilt virus and yield production.

Tomato-spotted wilt virus (TSWV) from the Tospovirus genus affects over 1000 plant species, including key crops, and traditional control methods often prove inadequate. This study investigates the effectiveness of Bacillus amyloliquefaciens and Bacillus subtilis in reducing TSWV infection, enhancing plant growth, and strengthening defense in Nicotiana benthamiana. The aim is to assess Bacillus as a sustainable biocontrol alternative, offering an eco-friendly solution for managing TSWV disease in agriculture. Here, we report the efficacy of five Bacillus isolates (out of 15 tested) - B. amyloliquefaciens (DJB5, YN48, YN28, Mg6) and B. subtilis L1-21 - significantly reducing TSWV copies per gram in N. benthamiana leaves, using a half-leaf assay. In glasshouse trials, isolates DJB5, YN48, and Mg6 decreased TSWV copies per gram by 75.7%, 83.6%, and 88.2%, with biocontrol efficacy rates of 91.2%, 94.1%, and 95.7% respectively. All the isolates consistently mitigated the symptoms of TSWV, reduced the disease severity, and area under the disease progress curve (AUDPC) at 21 days post-inoculation. Additionally, these isolates enhanced plant growth parameters, including shoot and root length, leaf number, area, and biomass. The application of endophytes in the infected plants activated antioxidant defense enzymes by elevating the activities of polyphenol oxidase (PPO), peroxidase (POD), superoxide dismutase (SOD), and chitinase. However, defense-related enzymes, such as malondialdehyde (MDA), catalase (CAT), phenylalanine ammonia-lyase (PAL), total phenol, and β-1,3-glucanase decreased as TSWV infection reduced in the leaves. Our findings indicate that B. amyloliquefaciens isolates, DJB5, YN48, and Mg6, effectively manage TSWV by activating plant defense, reducing virus load, reducing TSWV symptoms, and promoting plant growth. © 2024 Society of Chemical Industry.

Exploring the antidiabetic activity of potential probiotic bacteria isolated from traditional fermented beverage.

Type 2 Diabetes continues to be one of the major public health issues worldwide without any sustainable cure. The modulation of gut microbiota is believed to be caused by probiotic bacteria and several probiotic strains have previously shown antidiabetic activity. The present study aims to isolate potential probiotic bacteria from traditionally used fermented rice beer of Assam, India and to investigate its anti-hyperglycemic effect. Of the 20 isolated bacterial isolates, 5 isolates showed potential probiotic activities, of which, 2 isolates viz. Bacillus sp. FRB_A(A) and Acetobacter sp. FRB_B(S) showed good in vitro anti-oxidant and anti α-glucosidase activities. Based on the in vitro results, isolate Bacillus sp. FRB_A(A) was further used to evaluate the antidiabetic activity in streptozotocin induced diabetic rat model. After 21 days, the blood glucose level in diabetic rats with probiotic administration significantly lowered from 458.00 ± 46.62mg/dl to 108.20 ± 6.76mg/dl (p < 0.001), whereas, in diabetic rats without probiotic remained high (576.20 ± 29.48mg/dl). On analyzing the endogenous antioxidant profile in various tissues of the experimental rats, reduced lipid peroxidation, glutathione level and superoxide dismutase and glutathione peroxidase activity were observed in probiotic administered rats in comparison to the streptozotocin treated diabetic controls. In conclusion, the bacteria Bacillus sp. FRB_A(A) isolated from fermented rice beer possesses probiotic attributes and exhibits significant anti-hyperglycemic activities.

Role of exopolysacharide bacteria in improving the tolerance of Zea mays (L.) Seedlings to drought stress

In this study, 20 Bacillus and 20 Pseudomonas bacteria were isolated from arid and semiarid soil samples. Bacillus and Pseudomonas bacteria are soil-dwelling bacteria that can promote plant growth. They are known to produce exopolysaccharides (EPS), which can help plants retain water and tolerate drought stress. The isolates were morphologically and microscopically characterized and tested for their ability to produce exopolysaccharides. The isolates that were most capable of producing exopolysaccharides were used as biofertilizer to improve drought tolerance of maize seedlings. The seedlings were irrigated every 24, 48, or 72 h. The results showed that biofertilizers containing the most EPS-producing Bacillus and Pseudomonas isolates, B. subtillus, B. brevibacillus, P. putida, P. fluorescens, significantly improved the transpiration rate, stress tolerance index, drought tolerance, chlorophyll stability and membrane damage index of maize seedlings.

BIOLOGICAL ACTIVITY OF IRON CHELATES BASED ON BACILLUS SP.

Introduction. Iron is one of the most important essential elements for all living organisms and one of the most common metals in the earth's crust and soils. The aim of the work: to evaluate the biological activity of iron chelate complexes obtained by the method of targeted bacterial synthesis based on soil isolates of Bacillus sp., in relation to bacteria, fungi and higher plants. Material and methods. Soil samples taken near quarries of non-ferrous and ferrous metallurgy mining enterprises (quarry of PJSC Gaisky Mining and Processing Plant, quarry and "blue" lake of the Blyavinsky copper-pyrite deposit of OOO MMSC, Orenburg region) served as a source of metal-resistant strains of Bacillus sp. The diffusion method of agar wells, serial dilutions, "replicas" were used, phytotesting was carried out in accordance with ISO 11269-2:2012 and GOST 12038-84. Results. The obtained in the process of one-stage interaction of the destructured biomass of the B. cereus sample Cu pit with a solution of FeSO47H2O (precursor) at a concentration of 0.125 M in a ratio of 1:10 has a high potential for use as a bactericidal complex characterized by a pro-nounced inhibitory effect on S. aureus and P. aeruginosa (p &lt; 0.01). In a model experiment on Triticum aestivum and Sinapis alba, a reliably significant stimulation of the formation of chlorophyll a and b of both test cultures and an increase in compensatory mechanisms with an increase in their stress resistance were recorded. The study of fungicidal activity of test samples of biomaterial B. cereus Cu pit in combination with FeSO47H2O 0.250 M completely suppresses the growth of the studied fungi. Conclusions. The potential for using chelate complexes based on the iron-resistant strain B. cereus Cu pit is due to the level of its biological activity depending on the concentration of the introduced precursor.

Study on the Mobile Colistin Resistance (mcr-1) Gene in Gram-Negative Bacilli in a Rural Tertiary Care Hospital in Western Maharashtra.

Colistin, a last-resort antibiotic for treating multidrug-resistant Gram-negative bacterial infections, has increased resistance as a result of the emergence of the mcr-1 gene. Themcr-1gene, which confers colistin resistance, is often carried on plasmids, facilitating its spread by horizontal gene transfer among bacterial populations. The rising prevalence of mcr-1-mediated resistance poses significant challenges for infection control and treatment efficacy. This study aimed to detect and investigate the prevalence of the mcr-1 gene among Gram-negative bacilli isolated from clinical specimens in a rural tertiary care hospital and to analyze the plasmid-mediated mechanisms of colistin resistance. A cross-sectional study was conducted over two years at Krishna Institute of Medical Sciences, Karad. Gram-negative bacilli were isolated from clinical specimens and identified using standard methodology. Antimicrobial susceptibility testing was performed by using the Vitek-2 Compact (bioMerieux, Marcy-l'Étoile, France) method and the colistin-resistance broth microdilution method (BMD). Polymerase chain reaction (PCR) was done for the presence of mcr-1 gene in colistin-resistant isolates. Out of 359 Gram-negative bacilli isolates, 93 (25.90%) demonstrated resistance to colistin. Among these resistant strains, the mcr-1 gene was identified in 13 (13.97%) of the isolates. The gene was predominantly found in Pseudomonas aeruginosa (8, 61.53%), followed by Klebsiella pneumoniae (3, 23.07%), Acinetobacter baumannii (2, 15.38%) among the 13 isolates. Out of the various specimens received, mcr-1 gene was found in endotracheal tube (4, 30.76%), urine (4, 30.76%), pus (3, 23.07%), sputum (1, 7.69%), and blood (1, 7.69%). Colistin minimum inhibitory concentration (MIC) value for these resistant isolates ranged from 4 to 16 µg/ml. The study highlights a significant prevalence of mcr-1 plasmid-mediated colistin resistance gene among Gram-negative bacilli in the hospital. This possibly highlights the frequent misuse of colistin in animal husbandry from this rural area. The findings underscore the importance of monitoring resistance patterns and implementing stringent infection control measures.

Application of statistical designs strategy to improve cellulase production using agro-waste residue by a novel isolate Bacillus licheniformis strain-MA1 and assessing the enzyme effect on apple juice quality

BackgroundCellulose is the major part of lignocellulosic biomass. It can be hydrolyzed into glucose units via specific enzymes called cellulases that have been applied in many commercial fields. There are several studies illustrate the influence of enzymes on apple juice clarification. However, to the best of our knowledge, the effect of microbial cellulase on volatile compounds of apple juice is not well known. The present study aimed to assess the effect of cellulase from a new bacterial isolate on the physicochemical properties of apple juice as well as volatile compounds. The hydrolysis of some polysaccharides (cellulose, hemicellulose, pectin) and polyphenols during apple juice production is necessary to reduce cloud sedimentation or color deterioration and increase the yield of juice. So, enzymes from new microbial isolates serve as processing aids to obtain clear juice with a high yield.ResultsCellulase-producing bacterium was isolated, characterized and molecularly identified as Bacillus licheniformis strain-MA1 with an accession number of ON840115. Optimization of medium parameters was implemented using Plackett–Burman design (PBd) followed by Box-Behnken design (BBd) of response surface methodology (RSM). The PBd revealed the three most important (significant) variables including carboxymethyl cellulose (CMC), corn cob, and peptone that had positive impact on cellulase production. Additionally, using the agricultural residue (corn cob) by the bacterial strain as a carbon source helps in reducing the costs of enzyme production, recycling the by-products, and preserving the environment. The optimized medium using PBd and BBd enhanced cellulase production from B. licheniformis strain-MA1 by 6.8-fold. A remarkable increase was observed in juice yield in enzyme treated-juice sample (88.2 ± 0.15%) in comparison with control juice (75.4 ± 0.09%). The total phenolic contents in cloudy and clarified apple juices were 0.957 ± 0.09 and 0.412 ± 0.03 mg/mL, respectively. Also, DPPH and FRAP assays showed a remarkable increase in antioxidant activity (Low IC50) in the control sample compared to enzyme treatment. Twenty-seven volatile compounds were extracted using headspace solid-phase microextraction-gas and analysis was performed by GC–MS. The identified volatile constituents belonged to several chemical classes: 15 esters; 6 alcohols; 4 aldehydes and 2 acids. The predominant class in apple juice volatile fraction was esters with a sweet and fruity odor.ConclusionThe crude cellulase obtained from the novel bacterial isolate B. licheniformis strain-MA1 was successfully applied as a clarifying agent in apple juice.

Isolation and characterization of halophilic Bacillus thuringiensis from local Egyptian sites and their potential against Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

BackgroundBacillus thuringiensis (Bt) serves as a peculiar soil microbe that is Gram-positive, rod-shaped, spore-forming, and aerobic facultative. It endures across a range of conditions and has been demonstrated to be an effective biological pest control agent against several insect pests. The main objective of the study is to isolate and recognize Bt bacteria from saline environments in Egyptian soil for biological surveillance uses.ResultsIsolates three, four, five, ten, eleven, twelve, and thirteen were found to be moderately tolerant, while isolate eight showed highly tolerant, but isolate six was found to be borderline extreme halophile. On the other hand, the other isolates showed extreme halophiles. To find out the presence of crystals, a scanning electron microscope was carried out and the result showed that the crystals ranged from spherical to bi-pyramidal spherical. Molecular analysis was carried out using universal primers to confirm the presence of cry genes. The results showed that 84.6% of the isolates contain cry seven and eight, whereas cry one and four are distributed by 92.3%. Cry two genes were found to be 100 percent in all tested and isolated cultures. Cry genes were present and distribution among isolated was detected using gene-specific primers. cry3Ba1 and cry8B showed the lowest and equal distribution among the isolates, while the cry2Ab2gene frequency distribution was (84.6%) among isolated cultures. Around six cry genes were found to be absent in all isolated cultures. The bioinsecticidal activity and bioassays were carried out to check the potential effect of halophilic Bt isolates against 1st instar larvae of the Fall Armyworm (FAW) Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). Mortality was calculated after infecting S. frugiperda with thirteen Bt isolates. The most virulent Bt isolate was isolate 7, followed by isolate 10, with LC50 values of 9.542 × 107 spores/ml and 1.289 × 108 spores/ml, respectively, after 72 h. Morphological traits of the larvae were carried out, to check the effect of Bt isolates as a biological control against the FAW.ConclusionTo protect and enhance the sustainability of field crops and vegetables, especially in new high salinity lands, from disease-causing insects such as FAW, it is necessary to identify new strains of Bt from these saline lands. In this field, local isolates of Bt from several regions in Egypt known for their high levels of salinity were documented and showed an effective bioinsecticide on FAW larvae.

Antagonistic Effects and Volatile Organic Compound Profiles of Rhizobacteria in the Biocontrol of Phytophthora capsici.

Phytophthora capsici is a devastating pathogen in horticultural crops, particularly affecting Capsicum annuum (pepper). The overuse of chemical fungicides has led to resistance development, necessitating alternative strategies. This study investigates the antagonistic effects of four rhizobacterial isolates (Bacillus sp., Pseudomonas putida, Bacillus subtilis, Bacillus amyloliquefaciens) against P. capsici, focusing on the production of volatile organic compounds (VOCs). Using in vitro dual culture assays, we observed a significant inhibition of mycelial growth and sporangia production, especially by B. subtilis and B. amyloliquefaciens. The GC-MS/SPME-HS analysis identified key VOCs responsible for these antagonistic effects. Our findings demonstrate that specific rhizobacteria and their VOCs offer a promising biocontrol strategy, potentially reducing the reliance on chemical fungicides and contributing to sustainable agriculture.

Investigation of the effect of urease bioadditives on porosity and water absorption of cement composites

The results of the application of the biomineralization process in concrete to improve concrete properties such as porosity and water absorption are presented. As a result of the research, an assessment of the activity of various bioadditives based on the Bacillus subtilis strain and isolates isolated from samples of chernozem soil of the Yelets district of the Lipetsk region was given.It was found that the immobilized bacteria slightly differ from the native form in terms of urease activity, however, when stored for more than 50 days. they maintain their activity at a high level, and native microorganisms lose their ability to function, reducing urease activity by 10 times practically to minimum values. It was also revealed that when using Portland cement of various types, there is a decrease in water absorption up to 30%, and porosity decreases up to 40%.The use of different types of fine aggregate also affects porosity, so when using the same parts of sand P1 and P2, porosity is lower than with a homogeneous fine aggregate.It was also noted that all samples had increased strength characteristics – compressive strength and bending strength by 15–25%, respectively. Thus, the use of bioadditives is optimal to achieve improved concrete characteristics.

Enhanced vitamin B12 production by isolated Bacillus strains with the application of response surface methodology

BackgroundVitamin B12 is a crucial B-group vitamin, first isolated from the liver due to its role in combating pernicious anemia. It is distinguished by its unique and complex structure, which makes its chemical synthesis challenging and expensive. Consequently, vitamin B12 is alternatively obtained through microbial fermentations. Molasses, an affordable and safe agro-industrial waste, can be used as a carbon source for vitamin B12 production, offering a cost-effective alternative to expensive sugars in the production medium.ResultsA total of 87 yeast, actinomycete, and bacterial isolates were screened for vitamin B12 production, with 15 isolates showing high productivity. Bacillus isolates were selected for further analysis using MALDI-TOF and molecular identification. These isolates were identified as four strains of Bacillus subtilis (MZ08, JT10, BY11, and JT17), one strains of Bacillus sp. (CB09), and one strain of Peribacillus acanthi (MZ01). Genetic circuits associated with vitamin B12 production were demonstrated in a closely related strain of Peribacillus acanthi MZ01 strain. Three strains (MZ01, MZ08, and JT17) were selected for further evaluation of vitamin B12 productivity under different sugar types (glucose, sucrose, fructose, lactose, and galactose) and varying inoculum sizes. The inoculum size significantly impacted vitamin B12 production, with an increase from 5 to 10% enhancing yields. The ability of the strains to produce vitamin B12 varied depending on the type of sugar used. Peribacillus acanthi MZ01 strain showed the highest productivity and subsequently, selected for optimizing vitamin B12 production conditions using response surface methodology. Furthermore, the optimized conditions were then applied to molasses-based medium to achieve high vitamin B12 yields by MZ01 strain.ConclusionIn this study, Peribacillus acanthi was characterized for the first time as a vitamin B12 producer, demonstrating high productivity among various tested strains. The optimization of production conditions using response surface methodology, further enhanced vitamin B12 yields, showcasing the strain’s efficiency in microbial fermentations. This research also highlights the potential of using molasses as a cost-effective alternative carbon source, significantly reducing production costs.

Isolation and selection of spore-forming bacilli with potential for self-healing of concrete

The self-healing of concrete through the use of bacteria is an ecological, sustainable, and environmentally friendly method that can replace time-consuming and costly repairs. The aim of this research was to isolate and select spore-forming bacilli with potential for concrete self-healing. Soil samples from the limestone mines of Simbal, Trujillo, La Libertad, Peru were used. These samples were processed to primarily isolate spore-forming bacteria. The self-healing potential of these bacteria was evaluated through their ability to produce the urease enzyme, grow at an alkaline pH, and produce calcium carbonate crystals in a culture medium with urea and CaCl2 at pH 8.0. The produced crystals were visualized with scanning electron microscopy and their calcium content was confirmed through EDS analysis. The isolated bacteria were identified by 16 S rRNA gene amplification by PCR as Bacillus sp and Streptomyces sp. It was observed that Bacillus sp. produces CaCO3 crystals with vaterite morphology, while Streptomyces sp. produces rhombohedral calcite crystals. It is concluded that the isolated bacteria have the potential to be used in concrete self-healing processes.

Effects of Bacillus spp. inoculation on suggested shoot tolerance mechanisms in lowland rice (Oryza sativa L.) grown under iron toxicity

AbstractBackgroundIn areas of lowland rice production, high iron concentrations in the soil often lead to yield reductions. Local adapted varieties possess different adaptation mechanisms, which, however, are not fully understood. Previous studies have shown that endophytic bacteria can influence plant tolerance to abiotic stresses, including iron toxicity.AimThis study aims at analyzing the effects of different Bacillus isolates on distinct shoot tolerance mechanism in different rice cultivars grown under iron toxicity.MethodsThree lowland rice cultivars, varying in their tolerance against iron toxicity (IR31785‐58‐1‐2‐3‐3, Sahel 108, Suakoko 8), were inoculated with three Bacillus strains (two of B. pumilus and one of B. megaterium). One week after Bacillus inoculation plants were subjected to high iron levels (1000 ppm) for 7 days. Leaf symptom scoring was used to assess tolerance levels. Activities of ascorbate peroxidase (APX), glutathione reductase (GR), catalase (CAT), superoxide dismutase (SOD), and guaiacol peroxidase (PRX) were measured by spectrophotometric assays. Transcription of genes related to iron toxicity (OsFER, OsFRO1, OsNRAMP6) was determined by RT‐qPCR. Bacterial production of NO was evaluated by measuring nitrite levels in the culture supernatants.ResultsIn general, iron toxicity affected the activities of APX, GR, CAT, and PRX but not SOD activity. Only PRX activity in response to iron differed between cultivars with a significantly stronger increase in IR31785‐58‐1‐2‐3‐3. Inoculation with B. pumilus Ni9MO12 led to higher activity of CAT in the leaf sheaths of all cultivars and an increase in GR activity in the sheaths that was significantly higher in Suakoko 8. In the young leaf blades of IR31785‐58‐1‐2‐3‐3, transcription of OsFRO1 and OsNRAMP6 was not significantly affected by Bacillus inoculation, whereas accumulation of OsFER mRNA was significantly higher in iron‐stressed, B. pumilus Ni9MO12 inoculated plants compared to non‐inoculated, non‐iron‐stressed plants. Nitrite concentration as an indicator for NO production was increased in B. pumilus Ni9MO12 culture supernatants.ConclusionOur results show that in the sensitive cultivar IR31785‐58‐1‐2‐3‐3 tolerance to iron toxicity increases when inoculated with B. pumilus Ni9MO12, coinciding with higher levels of ferritin transcription. NO production by the Bacillus isolate might confer the promotion of OsFER gene transcription in the inoculated plants.