Bacterium Bacillus Research Articles

EVALUATION OF THE EFFECTS OF MICROBIOLOGICAL AGENTS ON THE REGENERATION OF A NUTRIENT SOLUTION WHEN GROWING VIGNA RADIATA MICROGREENS IN FLOOD & DRAIN SYSTEMS

Purpose. To evaluate the effectiveness of different microbiological agents in improving the nutrient solution quality and stimulating the growth and development of the mung bean (Vigna radiata) microgreens. Methods. Statistical processing, field assessments, analytical calculations. The study was conducted in the laboratory using three main types of microbiological agents: bacteria of the genera Bacillus and Pseudomonas as well as Rhodopseudomonas palustris. The tests were conducted on samples of the mung bean (Vigna radiata) microgreens grown in Flood & Drain systems, with regular monitoring of the nutrient solution parameters (pH, concentrations of major macro- and microelements, toxic compounds). To analyze the effects of microbiological agents, I used standard methods of hydroponics and chemical analyses of the nutrient solution. The plant growth was assessed by measuring plant height, number of leaves and total biomass. Results. It was found that the microbiological agents significantly improved the nutrient solution quality. Bacillus subtilis- and Rhodopseudomonas palustris-based products reduced the concentrations of toxic compounds such as ammonium and nitrates and increased the levels of available nutrients. In the experiment, an improvement in the growth rates of the mung bean (Vigna radiata) microgreens and an increase in the number of leaves and total biomass were noted. An increase in the chlorophyll level in the leaves was observed, indicating an improvement in photosynthetic activity. Discussion. The results confirmed the positive effects of the microbiological agents on the nutrient solution quality and the growth of the mung bean (Vigna radiata) microgreens. The Rhodopseudomonas palustris- and Bacillus subtilis-containing products proved to be more effective compared to the other microbiological agents, supporting published data on their abilities to bioactivate nutrients and reduce toxic decay products. It was demonstrated that the use of the microbiological products based on Rhodopseudomonas palustris and Bacillus subtilis will allow for a reduction in costs for solution regeneration. Conclusions. The use of microbiological agents seems to be a promising approach to improve the quality and extend the period of use of nutrient solutions in Flood & Drain systems and to stimulate the growth of the mung bean (Vigna radiata) microgreens. The microbiological products based on Rhodopseudomonas palustris and Bacillus subtilis were highly efficient in maintaining optimal conditions for the growth and development of the mung bean (Vigna radiata) plants. Further research is recommended to optimize the dosage and application conditions of agents and to elucidate their interactions with other components of hydroponic systems.

SYNTHESIS, ANTIMICROBIAL AND ANTIFUNGAL ACTIVITY OF PLATINUM (II) AND PALLADIUM (II) COMPLEXES

The aim of the work is the synthesis of mono- and binuclear complexes of platinum (II) and palladium (II) containing terminal and bridging atoms of chlorine and sulfur as ligands and the study of their biological activity in relation to test cultures of Bacillus subtilis B4647, Aspergillus brasiliensis (niger) F679, Pseudomonas aeruginosa B8243, Escherichia coli. The composition and structure of the synthesized platinum (II) and palladium (II) complexes were established by methods of elemental analysis, X-ray photoelectron spectroscopy (XPS), IR spectroscopy, and X-ray diffraction (XRD) technique, which correspond to our results on the X-ray structural analysis of these complexes. Antimicrobial and antifungicidal properties were assessed by the ability of the synthesized complexes to suppress the vital activity of bacteria and fungi using the agar diffusion method and the in vitro dilution method. The results obtained showed high activity of the binuclear complex of palladium (II) (μ-S)[Pd2(SCH2CH2NH+ 3)2Cl4] and platinum (II) (μ-Cl)[Pt2(SCH2CH2NH2)2Cl2]∙3H2O of non-electrolyte type. Binuclear complexes of palladium and platinum, in contrast to mononuclear trans-[Pd(SCH2CH2NH2)2] and cis-[Pt(SCH2CH2NH2)2], exhibit higher antibacterial activity. The effectiveness of the antibacterial action of the non-electrolyte palladium complex against the bacteria Bacillus subtilis, Escherichia coli and fungi Aspergillus niger was more pronounced. The results of our study showed that by changing the structure of the complex, the composition and charge of the inner sphere, the number of coordination centers, the nature and dentacy of the ligands, it is possible to achieve a higher toxic effect of the complexes (μ-S [Pd2(SCH2CH2NH+ 3)2Cl4], μ-Cl [Pt2(SCH2CH2NH2)2Cl2]∙3H2O) in relation to bacteria and fungi.

The effect of Bacillus bacteria and nano clay on the properties of roller pavement concrete and self-healing of its cracks due to calcium carbonate deposition

ABSTRACT One of the best methods to enhance the strength and durability of concrete and repair the cracks is to use a self-healing mechanism, based on bacterial-induced calcite precipitation. In this study the effect of this mechanism was investigated on untreated roller concrete pavement containing nanoclay. The bacteria used in this study was Bacillus sphaericus. The specimens were characterized using permeability, compressive strength, tensile strength, and ultrasonic tests. At first, one face of the specimens was subjected to bacterial self-healing to permeability test and all faces to compressive and tensile strength test. Also, using a copper sheet, a standard crack was created on one side of the specimens, and then the repair rate of these cracks due to bacterial self-repair was investigated by ultrasonic testing. The results showed that permeability, compressive and tensile strengths improved by 2.2%, 7.1% and 14.4%, respectively in the treated specimens without nanoclay. Meanwhile, in concrete specimens containing nanoclay, the improvement rate increased. Also, the results of the ultrasonic test showed that repair occurs by this coating and its rate is 12% in nanoclay-treated specimens and 7% in treated specimens without nanoclay, which shows the positive effect of nanoclay in improving the bacterial repair of standard cracks.

Synthesis and characterization of nano phosphorus fertilizer from rock phosphate

Phosphorus is a vital macronutrient required for the growth and development of plants. The major concern regarding phosphorus (P) is low availability. Fertilizers are generally supplied to increase the crop growth. Rock phosphate(RP) is mainly used as the precursor for synthesizing phosphatic fertilizers. The applied phosphatic fertilizers are usually fixed in the soil and the excess fertilizers result in eutrophication and pollute the water bodies. To address these challenges nanofertilizer technology was created. In the present study, nano phosphorus fertilizer was developed using P-solubilizing bacteria (Bacillus megaterium) from RP. The nano RP was characterized using particle size analysis (PSA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). The size of nano RP using a particle size analyzer was ~450 nm with a polydispersity index of 0.803. The FTIR spectra of RP show the presence of phosphate minerals, whereas some peaks of RP were altered after bios olubilization of RP. The XRD pattern indicated the presence of apatite and calcite and the number of peaks of nano RP was 13, while RP has 25 diffraction peaks. The scanning electron microscope image of nano RP indicated the reduction in the crystalinity of RP.

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.

The Aphicidal and Repellent Activities of Oxymatrine, Bacillus amyloliquefaciens, Nimbecidine and Spinosad against Adults of Oleander Aphids (Aphis nerii Boyer De Fonscolombe) under Laboratory Conditions

Background: The study aimed to determine the effect of biological and chemical control against the oleander insect, Aphis nerii, under laboratory conditions. Methods: The current study was conducted in the Plant Protection Laboratory of Diyala Agriculture, Diyala Province, Baqubah district, Iraq, During May 2023 to evaluate commercial products, which included oxymatrine, spinosad, the bacteria Bacillus amyloliquefaciens and nimbecidine, in addition to alphacypermethrin pesticide with three concentrations of 10, 20 and 30% against adults of Oleander aphids, Aphis nerii, the study included two experiments, to evaluate the mortality rate and the second to evaluate the repellency rate under laboratory conditions. Result: The alphacypermethrin pesticide with a concentration of 30% recorded the highest mortality (93.3%) after 24 hours, while the bacteria Bacillus amyloliquefaciens with a concentration of 10% and the oil neem (nimbecidine) with a concentration of 30% recorded the highest mortality (63.3% and 63.3%, respectively), after 48 hours. The oxymatrine 30% and 20% were superior in recording the highest repellency (66.6% and 66.6%) after 5 and 15 minutes, respectivelyand the bacteria 20% recorded the highest repellency (60.0%) after 10 minutes. The results of this study indicate the possibility of replacing chemical pesticides with biological control agents as eco-friendly alternatives.

Bioprospecting of rhizobacteria with antagonistic activity against Fusarium spp., a parasite of cucumber (Cucumis sativus)

Objective: To identify bacteria of genus Bacillus which, isolated from the tomato and cucumber rhizosphere, have an antagonistic effect against Fusarium spp. isolated from cucumber plants in Culiacan, Sinaloa. Design/Methodology/Approach: Both the in vitro and in vivo antagonisms of rhizobacterial isolates against Fusarium spp. on cucumber plants were evaluated. Bacteria with the highest antagonistic effect were identified based on their morphological and molecular characteristics. Results: Isolates FA15 and FA16 showed the highest in vitro biological efficacy against Fusarium spp., with 50.0% and 61.36% inhibition of mycelial growth, respectively. Rhizobacterium FA15 achieved the highest biological efficacy (88.89%) against Fusarium spp. in cucumber plants, while rhizobacterium FA16 recorded a 59.27% efficacy. The morphological and molecular characterization of isolates FA15 and FA16 confirmed a 100% molecular identity between FA15 and Bacillus velezensis and FA16 and B. subtilis. Study Limitations/Implications: The rhizobacteria identified in this study inhibited the mycelial growth of the phytoparasite. Therefore, further studies about these rhizobacteria should be carried out to determine the potential antibiosis that may cause the inhibitory effect. Findings/Conclusions: During the search for native beneficial rhizobacteria, two bacteria that exercise a biologically-effective control over Fusarium spp were identified in Culiacan: Bacillus velezensis and B. subtilis. This finding offers an opportunity in the agricultural biotechnology field to study beneficial native species that could provide an alternative to the use of chemicals.

New-Generation Antibacterial Agent-Cellulose-Binding Thermostable TP84_Endolysin.

The increasing antibiotic resistance among bacteria challenges the biotech industry to search for new antibacterial molecules. Endolysin TP84_28 is a thermostable, lytic enzyme, encoded by the bacteriophage (phage) TP-84, and it effectively digests host bacteria cell wall. Biofilms, together with antibiotic resistance, are major problems in clinical medicine and industry. The challenge is to keep antibacterial molecules at the site of desired action, as their diffusion leads to a loss of efficacy. The TP84_28 endolysin gene was cloned into an expression-fusion vector, forming a fusion gene cbd_tp84_28_his with a cellulose-binding domain from the cellulase enzyme. The Cellulose-Binding Thermostable TP84_Endolysin (CBD_TP84_28_His) fusion protein was biosynthesized in Escherichia coli and purified. Thermostability and enzymatic activities against various bacterial species were measured by a turbidity reduction assay, a spot assay, and biofilm removal. Cellulose-binding properties were confirmed via interactions with microcellulose and cellulose paper-based immunoblotting. The high affinity of the CBD allows for a high concentration of the fusion enzyme at desired target sites such as cellulose-based wound dressings, artificial heart valves and food packaging. CBD_TP84_28_His exhibits a lytic effect against thermophilic bacteria Geobacillus stearothemophilus, Thermus aquaticus, Bacillus stearothermophilus, and Geobacillus ICI and minor effects against mesophilic Bacillus cereus and Bacillus subtilis. CBD_TP84_28_His retains full activity after preincubation in the temperatures of 30-65 °C and exhibits significant activity up to its melting point at 73 °C. CBD_TP84_28_His effectively reduces biofilms. These findings suggest that integrating CBDs into thermostable endolysins could enable the development of targeted antibacterial recombinant proteins with diverse clinical and industrial applications.

From Spores to Suffering: Understanding the Role of Anthrax in Bioterrorism.

Anthrax, caused by the bacterium Bacillus anthracis, stands as a formidable threat with both natural and bioterrorism-related implications. Its ability to afflict a wide range of hosts, including humans and animals, coupled with its potential use as a bioweapon, underscores the critical importance of understanding and advancing our capabilities to combat this infectious disease. In this context, exploring futuristic approaches becomes imperative, as they hold the promise of not only addressing current challenges but also ushering in a new era in anthrax management. This review delves into strategies to mitigate the impact of anthrax on global health and security, envisioning a future where our arsenal against anthrax is characterized by precision and adaptability. This article highlights the significant potential of anthrax as a bioweapon, while also highlighting current knowledge and strategies developed against this deadly pathogen. We have performed an extensive research and literature review in concordance with the criteria outlined by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A search strategy was conducted by using numerous keywords on various academic databases, yielding an initial set of 546 records along with 80 supplementary articles. The search included research papers, review papers, perspectives, clinical guidelines, and scientific blogs. The primary and secondary screening of the articles were conducted by 2 independent reviewers along with a third reviewer mitigating any discrepancies and biases encountered during the process. A set of inclusion and exclusion criteria were formulated, and a PICO framework was adapted based on which multiple records were analyzed and considered for the review. In total, 53 articles were selected after completing a comprehensive systematic literature review. This review proposes novel approaches and scientific analysis of the complexities surrounding anthrax in the context of bioterrorism, highlighting the emerging technologies and strategies employed for bioterrorism mitigation. The upcoming advancements in anthrax research will be based on cutting-edge technologies and innovative approaches that demonstrate great potential for prevention, detection, and treatment. These advancements may include the incorporation of synthetic biology techniques such as precise manipulation of biological components, nanoscale diagnostics, and Clustered regularly interspaced short palindromic repeats-based technologies, which could revolutionize our ability to combat anthrax on a molecular level. As these progressive methodologies continue to evolve, the integration of these technologies has the potential to redefine our strategies against anthrax, providing more accurate, personalized, and adaptable approaches to address the challenges posed by this infectious threat.

Metagenomic and Physicochemical Characterization of Diesel Contaminated Soil from University of Calabar Power Plant: In-Sights to Bacterial Diversity and Community Function

Petroleum-contaminated soils provide an ideal environment for hydrocarbon-degrading bacteria, necessitating the study of their microbial ecology and community changes. This research compared diesel-impacted power plant soil (PPS) from the University of Calabar with pristine soil (CSS) as a control, the samples (50 g) were randomly collected from depths of 0–15 cm, 15–30 cm, and 30–45 cm. Physicochemical and metagenomic analyses were conducted. Taxonomic profiling with functional gene analyses via COG and PRK frameworks performed. PPS displayed higher concentrations of organic carbon (7.02%), total petroleum hydrocarbons (8500 mg/kg), nitrogen (0.51%), phosphorus (3.65 g/kg), lead (175 mg/kg), iron (2619 mg/kg), and copper (196.55 mg/kg) than CSS. Conversely, CSS had higher pH, temperature, conductivity, and moisture content. Bacterial abundance was slightly higher in CSS (89.24%) than in PPS (87.47%), with distinct dominant microbial taxa between samples. Functional analysis identified COG Class I (lipid transport and metabolism) as the most abundant in PPS (32.37%), linked to the predominant hydrocarbon-degrading bacterium Bacillus amyloliquefaciens (26.24%), absent in CSS. In contrast, CSS had COG Class O (posttranslational modification) as the highest (94%). These results demonstrate that petroleum pollution promotes the growth of hydrocarbon-degrading bacteria, underscoring the ecological impacts of contamination on soil microbial communities.

TAXONOMIC COMPOSITION AND PHYSIOLOGICAL AND BIOCHEMICAL PROPERTIES OF CULTIVATED MICROORGANISMS ISOLATED FROM KUDURITE ROCKS OF THE PRIMORSKY KRAI AND THE REPUBLIC OF ALTAI (RUSSIA)

The reason for the consumption of rocks (kudurits) by wild animals has not yet been identified. One of the hypotheses of geophagy is a microbiological factor, i.e. rocks can be a source of microorganisms useful for wild animals. In this work, the composition of cultured microorganisms of kudurits of Primorsky Krai and the Altai Republic, as well as some physiological and biochemical properties of the isolated bacteria were studied using molecular genetic analysis of the 16S RNA gene. It has been shown that the studied breeds contain a high amount of physiological groups of bacteria (saprophytic, ammonifying, nitrifying, silicate, hydrolytic) and yeasts (106-109 cells/ml) useful for animals. Among the isolated culturable microorganisms in the curls of Primorsky Krai, representatives of the genus Pseudomonas, Bacillus, Rhodotorula, Paenibacillus, and Stenotrophomonas predominated. The bacteria of the genus Bacillus, Chryseobacterium, and Streptomyces dominated in the edible soils of Altai. Among the isolates, non-pigmented, motile (35-70%) catalase-positive (86-91%) and oxidase-negative (68-76%) rods (67-90%) predominated. All cultures were characterized by a high level of extracellular enzymatic activity, especially in relation to such substrates as casein (57-75%), starch (57-60%), urea (43-45%). The isolated microorganisms are able to develop in a wide range of temperatures (5-500C), pH (5-12), NaCl concentration (1-18%) and utilize a wide range of carbohydrates and alcohols. It has been established that the microorganisms and biologically active compounds they produce can be a factor that encourages animals to instinctively consume rocks. High antibiotic activity of the isolated cultures has been noted against opportunistic bacteria Staphylococcus aureus, Micrococcus luteus and phytopathogenic fungi Fusarium oxysporum.

Corrigendum to “Does the use of two probiotic bacteria (Latiplantibacillus plantarum and Bacillus toyonensis) as water additives enhance growth performance, the immune responses, antioxidative maintenance, water quality and intestinal bacterial counts of Nile tilapia?” [Aquac. Rep. 39 (2024) 102471

Corrigendum to “Does the use of two probiotic bacteria (Latiplantibacillus plantarum and Bacillus toyonensis) as water additives enhance growth performance, the immune responses, antioxidative maintenance, water quality and intestinal bacterial counts of Nile tilapia?” [Aquac. Rep. 39 (2024) 102471

Synthesis, Characterization, Biological, and Antioxidant Activity of New Metal Ion Complexes with Schiff Base Derived from 2-Hydroxybenzohydrazide

The study involved the synthesis of new complexes with tetradentate ligand (LH). The general formula of complexes was [M(LH)(H2O)2] with M of Ni2+, Co2+, Cu2+, and Zn+. The ligand was synthesized by treating the 2-hydroxybenzohydrazide with salicylaldehyde. The structural characteristics of ligands and complexes were analyzed using various techniques, including elemental analyses, magnetic susceptibility, molar conductivity, infrared, ultraviolet absorption, mass, and NMR spectroscopy studies. The physical measurements indicated that the prepared complexes are non-electrolyte and showed that the ligand is tetradentate when coordinated with metal ions through the nitrogen of azomethine (–C=N–), two oxygen atoms of O–H phenolic, and an oxygen atom of carbonyl (C=O) for benzohydrazide. It was found that Co2+, Cu2+, and Zn2+ complexes are octahedral, while Ni2+ complexes are square planar. The biological screening of the complexes demonstrates that the Schiff base metal complexes exhibit remarkable efficacy in combating microorganisms by utilizing Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli) bacteria, as well as Candida albicans fungi. Hence, their results were good in inhibition. Then, the potential of these prepared compounds as antioxidants was determined by inhibiting free radicals.

Bridging the Gap: biofilm-mediated establishment of Bacillus velezensis on Trichoderma guizhouense mycelia

Bacterial-fungal interactions (BFIs) are important in ecosystem dynamics, especially within the soil rhizosphere. The bacterium Bacillus velezensis SQR9 and the fungus Trichoderma guizhouense NJAU 4742 have gathered considerable attention due to their roles in promoting plant growth and protecting their host against pathogens. In this study, we utilized these two model microorganisms to investigate BFI. We firstly demonstrate that while co-inoculation of B. velezensis and T. guizhouense could promote tomato growth, these two microorganisms display mutual antagonism on agar solidified medium. To resolve this contradiction, we developed an inoculation method, that allows B. velezensis colonization of T. guizhouense hyphae and performed a transcriptome analysis. During colonization of the fungal hyphae, B. velezensis SQR9 upregulates expression of biofilm related genes (e.g. eps, tasA, and bslA) that is distinct from free-living cells. This result suggested an intricate association between extracellular matrix expression and hyphae colonization. In accordance, deletion epsD, tasA, or both epsD and tasA genes of B. velezensis diminished colonization of the T. guizhouense hyphae. The insights from our study demonstrate that soil BFIs are more complex than we understood, potentially involving both competition and cooperation. These intricate biofilm-mediated BFI dynamics might contribute to the remarkable diversity observed within soil microbiota, providing a fresh perspective for further exploration of BFIs in the plant rhizosphere.

The Leaf Essential Oils of Syzygium oblatum and Syzygium abortivum: Chemical Composition, Antimicrobial Activity, and Molecular Docking Study

Background and Objectives Syzygium (the family Myrtaceae) is a well-known genus in the field of food chemistry and medicinal purposes. The current study aims to provide a chemical analysis of essential oils from the fresh leaves of two Vietnamese Syzygium species Syzygium oblatum (Roxb.) Wall. ex Steudel and S. abortivum (Gagnep.) Merr. &amp; L.M.Perry. Methods Chemical compounds in essential oils were identified using GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analysis. The broth microdilution method was used for the antimicrobial assay. Docking stimulation aided experimental results. Results ( E)-Caryophyllene (27.89%), α-selinene (18.34%), β-selinene (17.48%), and α-pinene (5.20%) were identified to be the main compounds in S. oblatum leaf essential oil, whereas the leaf essential oil of S. abortivum was dominated by ( E)-caryophyllene (19.56%), δ-cadinene (11.03%), germacrene D (10.34%), and γ-muurolene (5.50%). It noted that both studied oil samples with the MIC/IC50 values of 8-32 µg/mL/4.56-10.37 µg/mL were comparable to the standard drugs in antimicrobial experiments against the Gram-positive bacteria Bacillus cereus and Enterococcus faecalis, and yeast Candida albicans. Molecular docking results showed that the main compound ( E)-caryophyllene primarily formed hydrophobic interactions with the microbial proteins C. albicans N-myristoyl transferase B. cereus patB1, and E. faecalis carbamate kinase with the binding affinities of −6.969, −6.342, and −5.530 kcal/mol, respectively Conclusion It is advised to isolate the main chemicals and conduct in vivo antibacterial experiments for both essential oils and their main compounds.

The Effect of Using Ureolytic Bacteria as Self-Healing Agent in Concrete on Workability, Density and Absorption

Abstract Concrete is one of the fastest growing construction materials in Indonesia. Concrete has a low tensile strength that causes concrete to crack easily. One way to overcome this is by using self-healing concrete. This concrete is able to repair small cracks. Ureolytic bacteria can be used as a medium in self-healing concrete. These bacteria undergo a CaCO3 precipitation process to produce calcite which later fills the cracks in the concrete. This research aims to determine the effect of the application of ureolytic bacteria on the workability, density, and absorption of high-strength concrete. Additionally, the study investigates the elemental composition of self-healing concrete using Bacillus sp., Solibacillus sp., and Staphylococcus sp. as the healing medium. In the study, the test specimens used were cubes measuring 5 cm × 5 cm × 5 cm. The tests carried out in this study were testing the workability, density, and absorption of concrete. In this study, ureolytic bacteria Bacillus sp., Solibacillus sp., and Staphylococcus sp. were used with variations of 0%, 0.5%, 0.6% and 0.7% by weight of fine aggregate. The lowest flow reduction value is found in the addition of Bacillus sp. 0.5% bacteria with a value of 2%. The decrease in density value in self-healing concrete is not too significant. The lowest decrease was found in concrete with the addition of Staphylococcus sp. 0.5% bacteria with a value of 0.3%. The lowest absorption value is found in the specimen without the addition of bacterial capsules, which is 2.44%. Energy dispersive X-ray spectroscopy (EDS) test results on ureolytic bacterial self-healing concrete show that there are elements of C, O, Mg, Al, Si, S, and Ca in this concrete.

Effect of ureolytic bacteria Bacillus sp. from local landfill for crack healing on flexural tensile strength of high-strength concrete

Abstract High-strength concrete made with large amount of cement augmented with additives causing high hydration heat and large shrinkage during hardening process, making it susceptible to cracks at early age due to its still low tensile capacity. These cracks must be mitigated early. Self-healing method using ureolytic bacteria Bacillus sp. as concrete crack-healing can be smart solution to overcome this problem. Urease enzyme produced by ureolytic bacteria can hydrolyze urea and Ca2+ (derived from CaCl2) added as precursors to precipitate CaCO3 as concrete cracks closure biologically. This study aims to analyze effect of ureolytic bacteria Bacillus sp. cultivated from local landfill Gampong Jawa, Banda Aceh as crack self-healing on flexural tensile strength of high-strength concrete. Bacteria were immobilized into diatomaceous earth to increase viability during casting and after residing in harsh environment of concrete which used as 10% substitution for fine aggregates. Concentration of bacteria and growth media used were varied by 0%; 0.5%; 0.6%; and 0.7% of cement weight. Specimens were beams measuring 100×100×400mm which was given 1D10 mm tensile reinforcement to prevent brittle failure during testing. First, an initial crack load of 60% of 7 days concrete flexural tensile strength was given, then treatment was carried out for 28 days in water to observe crack healing for 7, 14, 21 and 28 days. After completing crack healing phase, flexural tensile capacity testing was carried out until the specimens collapsed. The results showed that flexural tensile capacity of high-strength concretes was 5.49 ton, 5.69 ton, 5.89 ton and 5.86 ton respectively and the percentage of concrete crack closure after healing phase for 28 days after being initially cracked was 4.76%; 77.90%; 87.09%; and 89.09% each, at variations of Bacillus sp. 0.0%; 0.5%; 0.6%; and 0.7%. Optimum value was obtained at bacterial percentage of 0.7% resulting in an increase both in flexural tensile capacity of 6.74% and in crack healing efficacy of 84.27% compared to non-bacteria concrete.

Treatment of landfill leachate MBR effluent by ozone combined with a semi-aerobic aged refuse bioreactor

Given the issue of high concentrations of refractory organic matter in wastewater treated by landfill leachate membrane bioreactor (MBR), a wastewater which is not suitable for further biological treatment, ozone molecules can be used to interact with unsaturated bonds in the organic matter from landfill leachate, reduce the concentration of organic matter and generate a large number of microbially available carbon sources. The ozone combined with semi-aerobic aged refuse bioreactor (SAARB) system was established to treat effluent from MBR treatment of landfill leachate (MBRE). The results indicated that under optimal conditions (ozone dosage of 39.21 mg/min and reaction time of 60 min), in the SAARB, the removal of each pollutant was higher after recharge with effluent from ozone pre-oxidized MBRE (OLE) than after direct recharge with MBRE. Specifically, the average removal rates of color number (CN), light absorbance at 254 nm (UV254), chemical oxygen demand (COD), ammonium nitrogen (NH4+-N), and total nitrogen (TN) increased by 29.28 %, 35.64 %, 13.46 %, 26.85 % and 25.59 %, respectively. After long-term recharge with OLE, the α diversity of the microbial communities in the SAARB increased significantly, the adaptability to the environment and anti-interference ability were enhanced. Meanwhile, several dominant functional bacteria (Bacillus, norank_p_Crenarchaeota, Nitrosospira and unclassified_c_Gammaproteobacteria) were enriched. As a result, the ecological functional abundance distribution of microorganisms in SAARB changed, that is, the metabolic function of small molecular organic matter and the functional abundance related to nitrification and denitrification increased. And in this process, three environmental factors, UV254, NH4+-N and TN, had the greatest impact on the community composition of microorganisms within the SAARB. This study can provide a new method for the treatment of MBRE.

Construction of polylactic acid plastisphere microbiota for enhancing nitrate reduction in denitrification biofilters

Developing methods for reusing biodegradable plastics, like polylactic acid (PLA) straws, is highly needed. Here, PLAs were applied to substitute traditional commercial ceramic media (CCM) in denitrification biofilters. During long-term operation, replacing CCM with PLA significantly enhanced nitrate removal efficiency from 32.68–54.39 % to 41.64–66.26 %. Ammonia nitrogen effluent maintained below 0.5 mg/L in all reactors. PLA plastisphere shaped unique microbial communities, i.e., denitrifying bacteria Bacillus, Pseudomonas and Acidovorax preferred to inhabit or degrade PLA. Compared to CCM biofilms, PLA diminished the importance of stochastic process in biofilm assembly of PLA plastisphere. Metagenomic sequencing suggested that PLA biofilms possessed greater metabolic capabilities of denitrification and glycolysis compared to CCM. Additionally, Bacillus strain P01 isolated from PLA plastisphere demonstrated strong PLA depolymerization. Overall, this study revealed that PLA serves as carbon source and biofilm carrier, offering a promising approach to integrating plastic reuse with wastewater treatment.