Bacillus Sphaericus Research Articles

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

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

Isolation and Molecular Identification of Cellulase producing bacteria from soil and litter in Veerakkal forest area, The Western Ghats, India

The cellulolytic bacterial strains were screened from both soil and litter samples in different study sites of Veerakkal forest, Manar beat, The Western Ghats, India. In the current investigation, out of 64 and 48 differentiated total purified isolates, 53 soil isolates and 34 litter isolates were screened based on the CMC method. The percent wise calculation indicated that 82 % were cellulase positive while 18 % were negative in soil isolates. Likewise, 70 % of them were positive while 30 % were negative cellulase strains in litter isolates. The average hydrolysis capacity (HC) values ranged between 1.67 to 3.25 cm. The highly potential cellulolytic bacterial isolates viz. Bacillus thuringiensis, Bacillus licheniformis, Bacillus cereus, Bacillus sporothermodurans, Bacillus circulans, Bacillus albus, Bacillus amyloliquefaciens, Lysinibacillus sphaericus and Bacillus mobilis were identified from soil. Likewise, the litter cellulolytic bacterial species such as Bacillus sp., Lysinibacillus macroides, Bacillus paramycoides, Solibacillus silvestris, Pseudomonas stutzeri, Bacillus toyonensis, Bacillus subtilis, Bacillus pacificus, Bacillus flexus, Bacillus paranthracis and Pseudomonas putida were identified. The cellulolytic bacterial population was higher during the monsoon because of the presence of higher moisture content in leaf litter. However, the cellulolytic bacterial population of soil was higher during the pre-monsoon season because of the continuous breakdown of litter which inhaled more cellulolytic strains in the soil. Finally, it was concluded that corresponding with seasonal changes, the cellulolytic bacterial community also changed and it plays a significant role in the mineralization process.

Compatibility of commercially available biopesticidal formulations with Temperature Tolerant strain of <i>Trichogramma chilonis</i> (TTT) in pre- and post-release situations in laboratory

Laboratory experiments were conducted to evaluate the effect of some commercially available biopesticidal formulations, such as Bacillus thuringiensis var. kurstaki (2g/l), Bacillus sphaericus(2g/l), Beauveria bassiana (5g/l), Metarhizium anisopliae (5g/l), Lecanicillium lecanii (5g/l) on the Temperature Tolerant strain of Trichogramma chilonis (TTT). Two sets of experiments were conducted, in the first experiment, all the test biopesticides were sprayed on the egg cards prepared from Corcyra cephalonica eggs (pre-release situation) and percent parasitisation and adult emergence were recorded; in the second one, test bio pesticides were sprayed on the parasitized cards (post release situation) and adult emergence was recorded. The results revealed that percent parasitisation and adult emergence from treated cards in both the experiments are on par with the untreated control, hence they are considered safe and can be used along with TTT.

Exploring Antibacterial Activity and Bacterial-Mediated Allotropic Transition of Differentially Coated Selenium Nanoparticles

The use of metal nanoparticles (NPs) as antimicrobial agents has become a promising alternative to the problem of antibiotic-resistant bacteria and other applications. Silver nanoparticles (AgNPs) are well-known as one of the most universal biocide compounds. However, selenium nanoparticles (SeNPs) recently gained more attention as effective antimicrobial agents. This study aims to investigate the antibacterial activity of SeNPs with different surface coatings (BSA-coated, chitosan-coated, and undefined coating) on the Gram-negative Stenotrophomonas bentonitica and the Gram-positive Lysinibacillus sphaericus in comparison to AgNPs. The tested NPs had similar properties, including shape (spheres), structure (amorphous), and size (50-90 nm), but differed in their surface charge. Chitosan SeNPs exhibited a positive surface charge, while the remaining NPs assayed had a negative surface charge. We have found that cell growth and viability of both bacteria were negatively affected in the presence of the NPs, as indicated by microcalorimetry and flow cytometry. Specifically, undefined coating SeNPs displayed the highest percentage values of dead cells for both bacteria (85-91%). An increase in reactive oxygen species (ROS) production was also detected. Chitosan-coated and undefined SeNPs caused the highest amount of ROS (299.7 and 289% over untreated controls) for S. bentonitica and L. sphaericus, respectively. Based on DNA degradation levels, undefined-SeNPs were found to be the most hazardous, causing nearly 80% DNA degradation. Finally, electron microscopy revealed the ability of the cells to transform the different SeNP types (amorphous) to crystalline SeNPs (trigonal/monoclinical Se), which could have environmentally positive implications for bioremediation purposes and provide a novel green method for the formation of crystalline SeNPs. The results obtained herein demonstrate the promising potential of SeNPs for their use in medicine as antimicrobial agents, and we propose S. bentonitica and L. sphaericus as candidates for new bioremediation strategies and NP synthesis with potential applications in many fields.

Microbial Induced Calcite Precipitation (MICP) Potential of Ureolytic Bacillus sp. Isolated from the Soil of Eroded Ecosystems for Stabilizing and Improving the Fertility of Eroded Soils

The loss of soil from lands due to erosion has a negative effect on ecosystems and food security. Bacillus due to high catabolic capability is an appropriate candidate for application in biocementation process. The aim of this study is isolate and characterize Bacillus sp. with biocementation capability from various ecosystems. The isolates were separated from 400 samples, and characterized by biochemical and molecular methods include the amplification and sequencing analysis of gyrA and 16S rRNA genes. Growth in presence of urea, in different salinity, pH, and temperature, also scanning electron microscope (SEM), X-ray diffraction (XRD), and wind tunnel analysis were applied to determine biocementation ability. A total number of 195 isolates were recovered from environmental samples, of which 25 isolates (12.82%) were identified as urease-positive Bacillus which belonged to 10 species consisting of Bacillus subtilis five strains (20%), Bacillus vallismortis and Bacillus seohaeanensis four strains (16%) each, Bacillus mobilis, Bacillus pseudofirmus, Bacillus cohnii, Bacillus cereus, Bacillus alkalinitrilicus two strains (8%) each, and Bacillus sphaericus and Bacillus megaterium one strain (4%) each. Moreover, 15 urease-positive isolates (7.7%) belonging to Ralostenia, Actinomycete, and Halomonas genera were identified. Optimum conditions for microbial induced calcite precipitation (MICP) by isolates are 30 °C, pH 9, and 6% salinity. The highest rate of calcium carbonate formation and urease activity recorded in B. subtilis with 24.15 mg/mL of calcium carbonate and 4.40 × 103 unit/L of urease, followed by B. mobilis and B. alkalinitrilicus with 22.85 mg/mL of calcium carbonate and 3.93 × 103 unit/L of urease. After MICP the lowest soil loss ratio at a flow rate of 90 km/h, was observed in B. subtilis 100-fold reduction, followed by B. seohaeanensis, B. cereus, B. vallismortis, with 90, 85, 80-folds reduction, respectively. Results indicate that the diversity of Bacillus sp. offers the potential ability for adaptation to harsh and untapped environments, also showed that the use of MICP on the soil surface can have a very significant role in reducing soil losses due to wind erosion.

Study on Cellular Localization of Bin Toxin and its Apoptosis-inducing Effect on Human Nasopharyngeal Carcinoma Cells.

Bacterial pore-forming toxins, BinA and BinB together known as the binary toxin are potent insecticidal proteins, that share structural homology with antitumor bacterial parasporin-2 protein. The underlying molecular mechanism of Bin toxin-induced cancer cell cytotoxicity requires more knowledge to understand whether the toxin induced human cytotoxic effects occur in the same way as that of parasporin-2 or not. In this study, anticancer properties of Lysinibacillus sphaericus derived Bin toxin on HK1 were evaluated through MTT assay, morphological analysis and lactate dehydrogenase efflux assay. Induction of apoptosis was determined from RT-qPCR, caspase activity and cytochrome c release assay. Internalization pattern of Bin toxin in HK1 cells was studied by confocal laser-scanning microscopic analysis. Activated Bin toxin had strong cytocidal activity to HK1 cancer cell line at 24 h postinoculation. Both BinA and BinB treated HK1 cells showed significant inhibition of cell viability at 12 μM. Induction of apoptotic mediators from RT-qPCR and caspase activity analyses indicated the activation of programmed cell death in HK1 cells in response to Bin toxin treatment. Internalization pattern of Bin toxin studied by using confocal microscopy indicated the localization of BinA on cell surface and internalization of BinB in the cytoplasm of cancer cells as well as colocalization of BinA with BinB. Evaluation of cytochrome c release also showed the association of BinB and BinA+BinB with mitochondria. Bin toxin is a cytotoxic protein that induces cytotoxic and apoptotic events in HK1 cells, and may have high therapeutic potential as an anti-cancer agent.

Isolation and Characterization of Bacteria with High Electroactive Potential from Poultry Wastewater.

Natural resources are in short supply, and the ecosystem is being damaged as a result of the overuse of fossil fuels. The creation of novel technology is greatly desired for investigating renewable and sustainable energy sources. Microorganisms have received a lot of interest recently for their potential to transform organic waste into sustainable energy and high-value goods. New exoelectrogens that can transmit electrons to electrodes and remove specific wastewater contaminants are expected to be studied. In this study, we examined three distinct samples (as determined by chemical oxygen demand and pH) that can be used as anolytes to generate power in single-chamber and double-chamber microbial fuel cells using graphite electrodes. Wastewater from poultry farms was studied as an exoelectrogenic anolyte for microbial fuel cell power generation. The study examined 10 different bacterial strains, numbered A1 through A10. Due to their highly anticipated capacity to metabolize organic/inorganic chemicals, the diverse range of microorganisms found in poultry wastewater inspired us to investigate the viability of generating electricity using microbial fuel cells. From the investigated bacterial strains, the highest voltage outputs were produced by strains A1 (Lysinibacillus sphaericus) and A2 (Bacillus cereus), respectively, at 402 mV and 350 mV. Among the 10 different bacterial strains, strain A6 generated the least amount of electricity, measuring 35.03 mV. Furthermore, a maximum power density of 16.16 1.02 mW/m2 was achieved by the microbial fuel cell using strain A1, significantly outperforming the microbial fuel cell using a sterile medium. The strain A2 showed significant current and power densities of 35 1.12 mA/m2 and 12.25 1.05 mW/m2, respectively. Moreover, in the two representative strains, chemical oxygen demand removal and Coulombic efficiency were noted. Samples from the effluent anode chamber were taken in order to gauge the effectiveness of chemical oxygen demand removal. Wastewater had an initial chemical oxygen demand content of 350 mg/L on average. Strains A1 and A2 decomposed 94.28% and 91.71%, respectively, of the organic substrate, according to the chemical oxygen demand removal efficiency values after 72 h. Strains A1 and A2 had electron donor oxidation efficiencies for 72 h of 54.1% and 60.67%, respectively. The Coulombic efficiency increased as the chemical oxygen demand decreased, indicating greater microbial electroactivity. With representative strains A1 and A2, Coulombic efficiencies of 10% and 3.5%, respectively, were obtained in the microbial fuel cell. The findings of this study greatly advance the field as a viable source of power technology for alternative energy in the future, which is important given the depletion of natural resources.

Lemongrass Powder in Bio-Bs Effervescent Formulation of Lombok Island Local Isolate on Viability and Amount of Bacillus Sphaericus Toxin Crystal Protein for Control of Anopheles sp. Larvae

Bio Formula – BS effervescent (Bio- Bacillus sphaericus) is an Effervescent powder-shaped formula that is easy to use by the public. Lombok's local effervescent bio-BS isolated formula has a weakness in terms of smell. The results from the literature search that fragrant lemongrass has a distinctive smell and can kill Aedes aeygpti, but scientific data has not been obtained about the ability of fragrant lemongrass to kill Anopheles Sp in the form of larvae and mosquitoes. The study aimed to find out the effect of the combination formulation of Bio-BS Effervescent local isolate Lombok Island with the addition of lemongrass powder for viability and the amount of toxin crystal protein Bacillus sphaericus. This research method is exploratory and experimental in the laboratory with the design of Post Test Only Control Group Design. The study used six treatment formulations. Samples of Anopheles sp larvae research in Batu Layar lagoon, West Lombok regency and pelur lagoon in Peringgesela, East Lombok regency and from the results of colonization of larvae. The independent Variable is a combination formulation of Bio-BS Effervescent isolated locally from Lombok Island with the addition of fragrant lemongrass powder. The dependent variable is the mortality of Larvae Anophels Sp, Viability of B. Sphaericus, and Amount of Toxin Protein Production of B. Sphaericus. The larvae death rate, the concentration of cells/endospores, and the number of repeats in each container are then tabulated and analyzed using Probit Analysis with the help of MINITAB 16 software. B. sphaericus viability data and the amount of endospore toxin protein crystal production were descriptively analyzed.

Isolation and Identification of Endophytic Bacteria from Okra Plant and Evaluation of Its Efficiency Against Spiny Bollworm Erias insulana (Boisd)

Twenty-eight endophytic bacteria were isolated from Okra plant grown in several regions in Salah El-Din-governorate fields including Balad, Ishaqi, Tikrit and Baiji. Bacterial cell treatment of isolate SB1 gave the highest rates of mortality on the third instar larvae of the spiny bollworm E. insulana reached to 66.66%, followed by isolate SB 3, which reached to 53.33%, while the isolates ST2, ST5, ST6, SB4, SJ2, SJ3, SJ5, SS2, SS3, as well as the control did not achieve any mortality rate. The results of the treatment of bacterial filtrates in the third instar larvae of the spiny bollworm showed the highest mortality rate was 93.33% by the isolate SB1, followed by 80.00% by the isolate SB3, while the filtrates of bacterial isolates SS5, SS1, SJ7, SJ3, SB5, ST4, and ST3 did not achieve any mortality rate. The results of the molecular diagnosis according to the nucleotide sequence analysis of the 16S rRNA gene and the conformity with the strains recorded in the World Genetic Bank (NCBI) showed the highest bacterial isolates in killing the insect, which included the isolates SB1, SB3, SB6, SJ6, and ST7 return to the species Brevibacillus laterosporus, Bacillus amyloliquefaciens, Bacillus thuringiensis, Bacillus subtilis and Lysinibacillus sphaericus and recorded in the World Genetic Bank under the accession numbers ON844995.1, ON844985.1, ON844996.1, ON844994.1. ON845438.1, respectively.

A study on bacterial self-healing concrete encapsulated in lightweight expanded clay aggregates

Concrete is a widely used construction material susceptible to cracking due to internal and external stresses, affecting the long-term strength and durability of the structure. Self-healing concrete appears to be a promising solution to address this issue. For concrete, self-healing is naturally achievable to a certain extent by utilising unhydrated cement particles. However, to heal significant internal and external cracks over a long period, we need to develop new techniques to reach a practical level of self-healing. This study investigates autonomous self-healing concrete using Microbially Induced Calcite Precipitation (MICP). The concrete mix is created by incorporating Lightweight Expanded Clay Aggregate (LECA) encapsulated with Lysinibacillus sphaericus and Bacillus coagulans bacteria. Encapsulation is used to prolong the life of the bacteria and shield them from the highly alkaline environment of the concrete. A bacterial concrete mixture was made by replacing 20% coarse aggregate by volume with the bacteria-encapsulated LECA. The properties of self-healing concrete specimens were compared with conventional concrete specimens of grade M30. After curing, the cracked bacterial specimens underwent a 14-day wet and dry cycle to examine how well the bacteria healed the cracks. Then, the durability property was analysed based on water permeability and chloride penetration tests. The microstructure of concrete was examined using SEM and EDX analysis. Bacillus coagulans and Lysinibacillus sphaericus bacteria specimens showed favourable results compared to conventional concrete for hardened and durability tests performed. The two bacteria-encapsulated concrete also exhibited positive crack healing, and the macrocracks in the range of 0.1 to 0.5 mm were healed. A salt analysis confirmed the presence of Calcium Carbonate (CaCO3) in the healed portion of the concrete. Lysinibacillus sphaericus bacteria showed slightly better results than Bacillus coagulans, and both bacteria can be used for self-healing concrete applications.

Desymmetric Reductive Amination of 1,3-Cyclopentadiones to Single Stereoisomer of β-Amino Ketones with an All-Carbon Quaternary Stereocenter by Engineered Amine Dehydrogenases

Regio- and stereoselective reductive amination of diketones offers an attractive method to access chiral β-amino ketones with multiple stereocenters which are unique scaffolds and building blocks for bioactive molecules, but it is still a great challenge in organic chemistry. In this study, mutant amine dehydrogenases (LsAmDHs) were created by directed evolution of a l-phenylalanine dehydrogenase from Lysinibacillus sphaericus to catalyze the desymmetric reductive amination of 2,2-disubstituted-1,3-cyclopentadiones. Using these beneficial LsAmDHs, the corresponding (2R, 3R)-β-amino ketones with an all-carbon quaternary stereocenter were prepared with up to 99% de and ee and up to 84% isolated yields. A cyclopenta[b]hydroquinoline derivative was obtained from 2-methyl-2-(2′-bromobenzyl)-1,3-cyclopentadione or 2-methyl-2-(2′-chlorobenzyl)-1,3-cyclopentadione via sequential enzymatic desymmetric reductive amination and an intramolecular Buchwald–Hartwig cross coupling reaction. Molecular docking and dynamics simulations provided some insights into the roles of key mutations on the improved activity and excellent stereoselectivity toward these un-native substrates. This study not only developed biocatalysts to realize the unprecedented desymmetric reductive amination of 2,2-disubstituted-1,3-cyclopentadiones to the single stereoisomer of the corresponding β-amino ketones but also suggested that engineering of amine dehydrogenase provides a useful tool to address the challenges in asymmetric reductive amination of diketones.

Development and Application of Biopesticides for the Management of Disease Vectors and Pests of Public Health Importance

The development and practical use of natural products occurred in the late 1970s when a spore-forming bacterium producing enterotoxins was discovered. This organism was designated as Bacillus thuringiensis ssp. israelensis (Bti). By 1985, large quantities of Bti formulations were employed in mosquito and black fly control programs globally. As research efforts in this area continued, a second bacterium Bacillus sphaericus (Bsph) was isolated and found to be highly effective against most mosquito species. This entomopathogen found its way into mosquito control around 1997. Today, both these (Bti and Bsph) microbial control agents are produced by large-scale fermentation processes in many countries. Recent advances in formulation technology of both bacteria have increased their usefulness in vector control programs. Another soil bacterium known as Saccharopolyspora spinosa (Actinomycetes), was discovered, producing bioactive components known as spinosyn A and spinosyn D. Large-scale fermentation technology has been developed and the product known as spinosad was produced and developed in agriculture, and recently for use in public health. However, spinosad has not been used to any great extent in public health as yet. All three microbial control agents have a good margin of safety for mammals, birds, and wildlife and are environmentally friendly. Considerable efforts were directed toward developing plant extracts for vector control, especially mosquitoes. In this context, plant-based extracts were formulated for the control of larval and adult mosquitoes. Some of the plant parts were used in manufacturing mosquito coils which number into the billions on a worldwide basis; however, only a small proportion of coils are manufactured with plant-derived products. A major area for the development of plant-based products is the use of plant essential oils which are formulated in various ways for personal protection from the attack of hematophagous insects. A number of such insect-repellent products are commercialized in many countries. The public has the perception that plant-based and other natural products are environmentally friendly and safer to use for vector control or apply to human skin as personal protectants than synthetic chemicals. In this paper, we will dwell upon the research and development efforts leading to the development, production, and application of microbial control agents, and phytochemicals for the control of adult and preimaginal stages of disease vectors, as well as the development and use of plant essential oils for personal protection from anthropophilic insects.

Enhancement of the ligninolytic activity of Lysinibacillus sphaericus by the addition of MnSO4 and its impact on subsequent methane production from Oil Palm Empty Fruit Bunches (OPEFB)

Palm empty fruit bunches (OPEFB) is a recalcitrant agricultural waste not readily digested which is produced in abundance. The recently isolated bacteria, Lysinibacillus sphaericus is a facultative anaerobe which can digest lignin. The objective of this study was to determine if the addition of L. sphaericus and MnSO4 could aid the bioconversion of OPEFB, and if this could enhance methane production during subsequent anaerobic digestion (AD). The untreated OPEFB had a specific methane potential of 0.099 L/g VS which was doubled following pre-treatment with L. sphaericus. In the presence of 0.25 mM MnSO4 a further 1.5-fold increase in methane production was observed. This illustrates for the first time how the addition of inducers (MnSO4) can significantly enhance this bacteria's ability to degrade lignocellulose through enhancement of its lignin degrading enzymes. Thus, enabling this agricultural waste to be utilised more effectively for biogas production.

Bioremediation of heavy metals polluted environment and decolourization of black liquor using microbial biofilms.

With increased urbanization and industrialization, modern life has led to an anthropogenic impact on the biosphere. Heavy metals pollution and pollutants from black liquor (BL) have caused severe effects on environment and living organisms. Bacterial biofilm has potential to remediate heavy metals and remove BL from the environment. Hence, this study was planned to investigate the potential of microbial biofilms for the bioremediation of heavy metals and BL polluted environments. Eleven biofilm forming bacterial strains (SB1, SB2, SC1, AF1, 5A, BC-1, BC-2, BC-3, BC-4, BC-5 and BC-6) were isolated and identified upto species level via 16S rRNA gene sequencing. Biofilm strains belonging to Bacillus and Lysinibacillus sphaericus were used to remediate heavy metals (Pb, Ni, Mn, Zn, Cu, and Co). Atomic absorption spectroscopy showed significantly high (P ≤ 0.05) bioremediation potential by L. sphaericus biofilm (1462.0 ± 0.67µgmL-1) against zinc (Zn). Similarly, Pseudomonas putida biofilm significantly (P ≤ 0.05) decolourized (65.1%) BL. Fourier transform infrared (FTIR) analysis of treated heavy metals showed the shifting of major peaks (1637 & 1629-1647, 1633 & 1635-1643, and 1638-1633cm-1) corresponding to specific amide groups due to C = O stretching. The study suggested that biofilm of the microbial flora from tanneries and pulp paper effluents possesses a strong potential for heavy metals bioremediation and BL decolourization. To our knowledge, this is the first report showing promising biofilm remediation potential of bacterial flora of tanneries and pulp-paper effluent from Kasur and Sheikhupura, Punjab, Pakistan, against heavy metals and BL.

Addition of sodium alginate capsules containing Lysinibacillus sphaericus for self-healing of cracks in mortars

The biomineralization technique of crack remediation in construction mortar can be achieved through the incorporation of calcifying bacteria within the mortar matrix. However, the thermal and autogenous shrinkage associated with the hydration of cement can be detrimental to the survival of the bacterial spores. Encapsulation of the spores in a matrix such as superabsorbent hydrogels, specifically sodium alginate, can provide protection from such detrimental conditions while also serving as a water reservoir for the metabolic activity of the bacterial cells. This paper investigated the addition of sodium alginate capsules prepared through spherification in construction mortars, aiming to preserve and optimize rheological, physical and mechanical properties, and to release bacteria when cracks occur. Mortar formulations with capsules containing Lysinibacillus sphaericus were calculated in order to maintain the granulometric distribution of standard formulation, thus obtaining products with excellent rheological, physical and mechanical properties, and allowing the addition of up to 1% capsules. Multivariate analysis of variance was applied at each age, showing that formulations with capsules kept the same properties as the original formula. After cracking, it was possible to observe the action of the released bacteria, through the formation of crystalline structures at the cracks. The capsules were prepared through a simple and cheap process, and it was proved that not only they do not affect concrete properties, but also are effective in both protecting the bacteria during mixing and hardening and releasing it after cracking.

Soil bio-cementation treatment strategies: state-of-the-art review

Bio-cementation is a new sustainable approach that has gained popularity due to its low energy and carbon dioxide footprint compared with those of existing technologies for geotechnical and geoenvironmental engineering applications. Bio-cementation is a soil improvement technique that involves binding the pore space of soil particles with calcium carbonate minerals by microbially induced carbonate precipitation (MICP) and filling the soil pore space. The purpose of this paper is to present the current state of the art and a comprehensive discussion on the development of bio-cementation for soil improvement/reinforcement. Premixing, injection, immersing and surface percolation are identified as four distinct bio-cementation treatment techniques. Furthermore, scholars have reported employing ureolytic bacteria such as Sporosarcina pasteurii, Bacillus sphaericus and Lysinibacillus sphaericus isolated from corals, limestone caves, soils, waste materials, seawater and other sources to accomplish effective bio-cementation. Some of the major issues (bacterial cultivation costs and ammonium production) that impede its industrial potential and promising remedial techniques are also discussed. This state-of-the-art review also discusses the benefits and drawbacks of bio-cementation compared with traditional approaches. The significance of enzyme-induced carbonate precipitation as a soil bio-cementation alternative to MICP is also highlighted. Finally, the sustainable procedure, bio-cementation principles and future implications are discussed.

Impact of rhizobacteria community of citrus root on Tylenchulus semipenetrans and on Citrus plant growth

ABSTRACT Tylenchulus semipenetrans Cobb, is a parasitic nematode of citrus, causing significant reduction in citrus growth and yield. Biological antagonists including bacteria and fungi have been used to control citrus nematodes. Citrus rhizosphere bacteria were collected from mature orchards in Tunisia and they have been studied to evaluate their nematicidal potentials on citrus nematode and abilities to stimulate plant root growth. Sixty bacterial strains isolated from egg masses of citrus nematode, citrus roots and associated to nematode trapping fungi, were tested for their abilities to parasitize T. semipenetrans and their impact on citrus growth parameters. The data analysis revealed that Bacillus weihenstephanensis, Lysinibacillus sphaericus, Bacillus subtilis, Bacillus thuringiensis, Bacillus pumilus and Bacillus cereus showed the highest effectiveness on T. semipenetrans juvenile (J2) causing up to 85% mortality of juveniles (J2) after 6 days of exposure in vitro. B. subtilis, B. amyloliquefaciens, B. pumilus and B. weihenstephanensis also inhibited egg hatching of citrus nematode in vitro. Furthermore, the majority of these rhizobacteria significantly stimulated citrus growth parameters. The application of B. weihenstephanensis, B. cereus, B. mycoides, B. thuringiensis, L. sphaericus, and Alcaligenes faecalis stimulated sour orange root growth in vitro compared to the control. Citrus rhizosphere bacteria must be studied further due to their diversity, abundance, and ability to effectively control T. semipenetrans.

Interspecies Horizontal Transfer and Specific Integration of the Mosquitocidal Toxin-Encoding Plasmid pTAND672-2 from Bacillus thuringiensis subsp. israelensis to Lysinibacillus sphaericus.

pTAND672-2, a 144-kb resident plasmid of Bacillus thuringiensis serovar israelensis strain TAND672, was sequenced and characterized. This extrachromosomal element carries mosquitocidal toxin-, conjugation-, and recombinase-encoding genes, together with a putative arbitrium system, a genetic module recently discovered in temperate phages controlling lysogeny-lysis transition and in mobile genetic elements (MGEs) where its function remains clarified. Using conjugation experiments, pTAND672-2 is shown to be a novel integrative and conjugative element (ICE), which can horizontally transfer from B. thuringiensis serovar israelensis to Lysinibacillus sphaericus, another mosquitocidal bacterium, where it integrates into the chromosome. Its integration and circularization are reversible and involve a single-cross recombination between 33-bp specific sites, attB in the chromosome of L. sphaericus and attP in pTAND672-2. CDS143, coding for the putative tyrosine integrase Int143 distantly related to site-specific tyrosine Xer recombinases and phage integrases, can mediate the integration of pTAND672-2 to attB. The B. thuringiensis mosquito-killing genes carried by pTAND672-2 are efficiently transcribed and expressed in L. sphaericus, displaying a slight increased toxicity in this bacterium against Aedes albopictus larvae. The occurrence of pTAND672-2-like plasmids within the Bacillus cereus group was also explored and indicated that they all share a similar genetic backbone with diverse plasmid sizes, ranging from 58 to 225 kb. Interestingly, among them, the pEFR-4-4 plasmid of Bacillus paranthracis EFR-4 and p5 of B. thuringiensis BT-59 also display conjugative capability; moreover, like pTAND672-2 displays a chimeric structure between the pCH_133-e- and pBtoxis-like plasmids, pBTHD789-3 also appears to be mosaic of two plasmids. IMPORTANCE Horizontal transfer of mobile genetic elements carrying mosquitocidal toxin genes may play a driving role in the diversity of mosquitocidal bacteria. Here, the 144-kb mosquitocidal toxin-encoding plasmid pTAND672-2 is the first verified integrative and conjugative element (ICE) identified in Bacillus thuringiensis serovar israelensis. The key tyrosine integrase Int143, involved in the specific integration, is distantly related to other tyrosine recombinases. The study also reports the occurrence and potential interspecies transmission of pTAND672-2-like plasmids with varied sizes in B. thuringiensis, Bacillus paranthracis, and Bacillus wiedmannii isolates belonging to the Bacillus cereus group. This study is important for further understanding the evolution and ecology of mosquitocidal bacteria, as well as for providing new direction for the genetic engineering of biopesticides in the control of disease-transmitting mosquitoes.

Clove leaf-based magnesium nanoparticles synthesis for antimicrobial applications

Nanoparticles can be synthesized by various chemical, physical, or biological methods. Chemical and physical methods have certain drawbacks such as time consuming, high cost, high energy requirement, low yield and also produces hazardous chemicals which will be harmful to environment. Bio-synthesis seems a possible solution for the environment friendly synthesis of nanoparticles with enhances stability and clean synthesis technology to minimize environment and health associated risk. Bio nanotechnology encourages replacement of existing products with new environment friendly nano-products. Present study reports, the plant-based synthesis of magnesium nanoparticles with Syzygium aromaticum and their characterized with Dynamic Light scattering, Scanning Electron Microscope, UV-spectrophotometer and Fourier transfer infrared (FTIR). Bio-synthesized nanoparticles show promising antimicrobial activity against Gram + ve (Bacillus sphaericus, Bacillus subtilis) and Gram -ve bacteria (Escherichia coli) group of Microorganisms.

Pelgipeptins, a Nonribosomal Lipopeptide Family, Show Larvicidal Activity against Vectors Transmitting Viruses

Aedes aegypti and Culex quinquefasciatus are vectors of numerous diseases of worldwide public importance, such as arboviruses and filariasis. The main strategy for controlling these vectors is the use of chemicals, which can induce the appearance of resistant insects. The use of Bacillus thuringiensis (Bt) and Lysinibacillus sphaericus (Ls) with larvicidal activity against arboviral-transmitting insects has been successful in many studies. In contrast, the use and knowledge of peptides with insecticidal activity are so far scarce. In this work, 25 peptides and 5 strains of each bacterial species were prospected individually or together regarding their insecticidal activity. Initially, in vitro assays of cellular cytotoxicity of the peptides against SF21 cells of Spodoptera frugiperda were performed. The peptides Polybia-MPII and pelgipeptin caused 69 and 60% of cell mortality, respectively, at the concentration of 10 μM. Thus, they were evaluated in vivo against second-stage larvae of the two Culicidae. However, in the in vivo bioassays, only pelgipeptin showed larvicidal mortality against both larvae (LC50 6.40 μM against A. aegypti, and LC50 1.22 μM against C. quinquefasciatus). The toxin-producing bacterial strain that showed the lowest LC50 against A. aegypti was Bt S8 (LC50 = 0.71 ng/mL) and against C. quinquefasciatus, it was Ls S260 (LC50 = 2.32 ng/mL). So, the synergistic activity between the association of the bacterial toxins and pelgipeptin was evaluated. A synergic effect of pelgipeptin was observed with Ls strain S260 against C. quinquefasciatus. Our results demonstrate the possibility of synergistic or individual use of both biologically active larvicides against C. quinquefasciatus and A. aegypti.