Paenibacillus Polymyxa Research Articles

Preservation of Paenibacillus polymyxa BTK01 and Bacillus subtilis BTK07 as lignocellulolytic bacterial starters for industrial applications: Physicochemical conditions, enzyme stability, freeze-drying processes and cryoprotection

In a previous study, Paenibacillus polymyxa BTK01 (BTK01) and Bacillus subtilis BTK07 (BTK07) were identified as lignocellulolytic strains that produced xylanase (XLN) and mannanase (MNN), respectively. As a biocontrol agent and a biofertilizer, these bacteria can be beneficial for organic agriculture, and they could be developed by upscaling as a bacterial starter. Moreover, the enzymes produced can be useful in the wood pulp industry. Therefore, this study focused on determining the physicochemical conditions for enzyme catalysis and for preserving BTK01 and BTK07 using a freeze-drying process. We show that the optimum physicochemical conditions for XLN and MNN produced by these strains were clearly defined by pH 7–8 and 40–60 °C, in which the lignocellulolytic enzymes of BTK01 were thermally stable. The XLN from BTK01 was stable at 40 °C but became unstable at lower temperatures. As expected, freeze-drying without cryoprotectant reduced bacterial survival rather than enzymatic activity, but the 30-day-storage of the freeze-dried bacteria primarily affected enzyme catalysis. For added value, the fermentation broth could be divided into sediment and supernatant to obtain freeze-dried products as a bacterial starter and a crude enzyme, respectively. Additionally, formulating skimmed milk and glycerol as a cryoprotectants could improve bacterial survival and enzymatic activity of freeze-dried bacteria, particularly BTK07. Accordingly, the results indicate that the freeze-dried products of BTK01 and BTK07 are suitable for industrial-scale production to supply the agricultural sector and other related fields.

The Potential Biocontrol Agent Paenibacillus polymyxa TP3 Produces Fusaricidin-Type Compounds Involved in the Antagonism Against Gray Mold Pathogen Botrytis cinerea.

Paenibacillus polymyxa is a beneficial bacterium for plant health. P.polymyxa TP3 exhibits antagonistic activity toward Botrytis cinerea and alleviates gray mold symptoms on the leaves of strawberry plants. Moreover, suppression of gray mold on the flowers and fruits of strawberry plants in field trials, including vegetative cells and endospores, was demonstrated, indicating the potential of strain TP3 as a biological control agent. To examine the anti-B. cinerea compounds produced by P.polymyxa TP3, we performed matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and fusaricidin-corresponding mass spectra were detected. Moreover, fusaricidin-related signals appeared in imaging mass spectrometry of TP3 when confronted with B. cinerea. By using liquid chromatography mass spectrometry-based molecular networking approach, we identified several fusaricidins including a new variant of mass/charge ratio 917.5455 with serine in the first position of the hexapeptide. Via advanced mass spectrometry and network analysis, fusaricidin-type compounds produced by P. polymyxa TP3 were efficiently disclosed and were presumed to play roles in the antagonism against gray mold pathogen B. cinerea.

Genetic Diversity and Characterization of Plant Growth-Promoting Effects of Bacteria Isolated from Rhizospheric Soils

Plant growth-promoting rhizobacteria (PGPR) have the potential to make a significant contribution to the development of sustainable agricultural systems. Generally, PGPRs function in three different ways, summarized as the synthesis of certain compounds for plants, facilitating the uptake of certain nutrients from the soil and protecting plants from diseases. This study aims to isolate plant growth-promoting bacteria from different plant rhizospheres from Ankara province, to reveal their genetic diversity, and to determine their plant growth-promoting properties. The identification of the 69 isolates was made according to the 16S rDNA sequence results and ARDRA analyses were also performed using AluI, HeaIII, and MspI enzymes. Nitrogen fixation, phosphate dissolving, IAA (indole-3-acetic acid) and siderophore production capacities of the 69 bacterial strains including 12 different genera (30 Pseudomonas, 13 Arthrobacter, 7 Bacillus, 4 Phyllobacter, 4 Variovorax, 3 Olivibacter, 3 Enterobacter, 2 Paenarthrobacter, 1 Stenotrophomonas, 1 Flavobacterium, 1 Caulobacter, 1 Paenibacillus) were evaluated in in vitro conditions. Nitrogen fixation capacities of 55 isolates varied between 2.29 and 46.11µgmL-1 according to micro-kjeldahl method. Among the strains studied, nifH gene was detected only in Paenibacillus polymyxa H8/2 strain. The highestPhosphorus dissolving and IAA production capacity (in tryptophan-added medium) of isolates were 186.52µgmL-1, and50.05μgmL-1 respectively, and 31 of 69 isolates were able to produce siderophore. Regarding antifungal activities, results showed that 31 bacterial isolates had antagonistic activities against at least one of the tested pathogens. Nitrogen fixation and phosphate solubilizing potential of the promising bacterial strains were determined through two-independent pot experiments with wheat and it has been found that they have positive effects on the yield parameters of wheat.

Occurrence of phenotypic variation in Paenibacillus polymyxa E681 associated with sporulation and carbohydrate metabolism

We report the phenotypic variation in Paenibacillus polymyxa E681 (E681), a plant growth-promoting rhizobacterium (PGPR) isolated from a winter barley root in Korea. Phenotypic variation (F-type) occurred when E681 (B-type) was grown in the media, and F-type was generated from B-type. B- and F-types were characterized by their morphological, Biolog, and GC-MIDI analyses. F-type cells altered the original biological capacity of B-type cells on endospore and flagella formation, changes in pH in culture, and carbon utilization. In growth curve analysis, B-type variants recovered bacterial growth as the variation occurred after the decline phase, but F-type variants did not. To determine this cause, we conducted comparative proteome analysis between B- and F-types using two-dimensional gel electrophoresis (2-DE). Of the identified proteins, 47% were involved in glycolysis and other metabolic pathways associated with carbohydrate metabolism. Therefore, our findings provide new knowledge on the mechanism of phenotypic variation and insights into agricultural biotechnology.

Production of Different Biochemicals by Paenibacillus polymyxa DSM 742 From Pretreated Brewers' Spent Grains.

Brewers’ spent grains (BSG) are a by-product of the brewing industry that is mainly used as feedstock; otherwise, it has to be disposed according to regulations. Due to the high content of glucose and xylose, after pretreatment and hydrolysis, it can be used as a main carbohydrate source for cultivation of microorganisms for production of biofuels or biochemicals like 2,3-butanediol or lactate. 2,3-Butanediol has applications in the pharmaceutical or chemical industry as a precursor for varnishes and paints or in the food industry as an aroma compound. So far, Klebsiella pneumoniae, Serratia marcescens, Clostridium sp., and Enterobacter aerogenes are being used and investigated in different bioprocesses aimed at the production of 2,3-butanediol. The main drawback is bacterial pathogenicity which complicates all production steps in laboratory, pilot, and industrial scales. In our study, a gram-positive GRAS bacterium Paenibacillus polymyxa DSM 742 was used for the production of 2,3-butanediol. Since this strain is very poorly described in literature, bacterium cultivation was performed in media with different glucose and/or xylose concentration ranges. The highest 2,3-butanediol concentration of 18.61 g l–1 was achieved in medium with 70 g l–1 of glucose during 40 h of fermentation. In contrast, during bacterium cultivation in xylose containing medium there was no significant 2,3-butanediol production. In the next stage, BSG hydrolysates were used for bacterial cultivation. P. polymyxa DSM 742 cultivated in the liquid phase of pretreated BSG produced very low 2,3-butanediol and ethanol concentrations. Therefore, this BSG hydrolysate has to be detoxified in order to remove bacterial growth inhibitors. After detoxification, bacterium cultivation resulted in 30 g l–1 of lactate, while production of 2,3-butanediol was negligible. The solid phase of pretreated BSG was also used for bacterium cultivation after its hydrolysis by commercial enzymes. In these cultivations, P. polymyxa DSM 742 produced 9.8 g l–1 of 2,3-butanediol and 3.93 g l–1 of ethanol. On the basis of the obtained results, it can be concluded that different experimental setups give the possibility of directing the metabolism of P. polymyxa DSM 742 toward the production of either 2,3-butanediol and ethanol or lactate.

Apple leaf macro- and micronutrient content as affected by soil treatments with fertilizers and microorganisms

The effects of bacterial and fungal inocula on the nutritional status of ‘Sampion’ apple trees was evaluated in three-years study (2018–2020). The experiment was set up in a two-factor system: (i) fertilization (without fertilization or mineral fertilization with nitrogen, phosphorus, potassium); (ii) application of beneficial microorganisms (without application, application of fungi or bacteria). The mixture of beneficial soil fungi contained two species: Aspergillus niger and Purpureocillium lilacinum. The mixture of beneficial bacteria contained three strains of Bacillus (Bacillus sp., Bacillus amyloliquefaciens and Paenibacillus polymyxa). The analysis of mineral content and leaf greenness (SPAD index) was performed on the samples collected from the trees in August. The lack of mineral fertilization caused a significant decrease in the nitrogen content of apple leaves, which resulted in their lighter color (lower SPAD index). The application of filamentous fungi or bacterial strains had a modifying effect on the mineral composition of apple leaves, what became evident especially in the third year of the study. An increase in the concentration of nitrogen, calcium, magnesium, sulphur and most microelements (except for boron) was found as a result of the influence of tree mineral fertilization and microorganisms applied to the soil. In the absence of mineral fertilization of the trees, the applied microbial inocula resulted in the significant increase of concentration of most macro- and microelements in the leaf tissue (except for magnesium and boron).

Population pharmacokinetics of polymyxin B: a systematic review.

BackgroundPolymyxin B (PMB) is a basic cyclic polypeptide antibiotic produced by Bacillus polymyxa, and is one of the last options for treating multi-drug-resistant negative bacterial infections in clinical practice. In recent years, many population pharmacokinetic studies of PMB have been conducted. This paper sought to comprehensively summarize the characteristics of population pharmacokinetic models of PMB and provide a theoretical basis for the individualized use of PMB.MethodsIn this review, we systematically searched the PubMed and Embase databases to find articles on population pharmacokinetic models published from database establishment to August 2021.ResultsA total of 10 studies were included in this review, including studies on various types of severe infections caused by multi-drug-resistant bacteria, hospital-acquired infections with fibrosis and other male and female populations, and a study of 2 continuous renal replacement therapy (CRRT) patients, aged 16–94 years, who received PMB doses of 10–360 mg/day (0.13–3.45 mg/kg/day), at an administration time of 0.5–6 hours. First-order linear elimination was used in all the studies; a 1-compartment model was used in 5 studies, and a 2-compartment model was used in 5 studies. The most common covariates were creatinine clearance (CrCL) and body weight.DiscussionAlthough these studies included several covariates and total clearance (CL) was close, but the external validation of some models was poorly correlated between the actual and predicted value. Novel or potential covariates represent important directions for further study.

Nitrogen fixation by Paenibacillus polymyxa WLY78 is responsible for cucumber growth promotion

To study nitrogen contribution to cucumber derived from nitrogen fixation of Paenibacillus polymyxa WLY78. The nif gene cluster deletion mutant (ΔnifB-V) of Paenibacillus polymyxa WLY78 was constructed by a homologous recombination method. The effects of plant-growth promotion were investigated by greenhouse experiments. The nitrogen fixation contribution was estimated by 15N isotope dilution method (also being called the 15N natural abundance technique). Deletion of nif gene cluster of P. polymyxa WLY78 resulted in complete loss of nitrogenase activity. Greenhouse experiments showed that inoculation with P. polymyxa WLY78 could significantly enhance the lengths and dry weights of cucumber roots and shoots, but inoculation with ΔnifB-V mutant could not. 15N isotope dilution experiments showed that cucumber plants derive 25.93% nitrogen from nitrogen fixation performed by P. polymyxa WLY78, but the ΔnifB-V mutant nearly could not provide nitrogen for plant growth. This present study demonstrated that nitrogen fixation performed by P. polymyxa WLY78 contributes to plant growth.

Whole-Genome Sequence of Paenibacillus polymyxa Strain SRT9.1, a Promising Plant Growth-Promoting Bacterium.

ABSTRACTPaenibacillus polymyxa SRT9.1 is an epiphytic bacterium capable of inhibiting plant-pathogenic bacteria. The strain has potential for development as a biocontrol agent for use in agriculture. We report the whole-genome sequence of Paenibacillus polymyxa SRT9.1, consisting of 6,754,470 bp and 7,878 coding sequences, with an average G+C content of 45%.

PENGARUH PUPUK HAYATI DENGAN KOMPOSISI MIKROORGANISME YANG BERBEDA TERHADAP PERTUMBUHAN TANAMAN

Biofertilizer can be used to replace chemical fertilizer so that soil quality is maintained and soil pollution can be avoided. The study aimed to determine the effect of biofertilizers with different compositions of microorganisms on the growth of maize plants. The research was carried out in a greenhouse. Maize plants were fertilized by two kinds of biofertilizers with different compositions of microorganisms. The first biofertilizer contained Azotobacter sp, Azospirillum sp, Rhizobium sp, Trichoderma sp, and Lactobacillus sp, and the second biofertilizer contained Strenotrophomonas sp. and Paenibacillus polymyxa. As controls, maize plants were fertilized by sterilized those biofertilizers. The results showed that the second biofertilizer increased the dry weight of the maize plant. Meanwhile, the first biofertilizer did not increase it. Several things must be considered in the application of biofertilizers, such as the composition of microorganisms, type of plant, level of fertilization, and the method of applying fertilizer to the plant.

Biocontrol of Anthracnose Disease on Chili Pepper Using a Formulation Containing Paenibacillus polymyxa C1

Anthracnose disease on chili pepper has been known to seriously interfere with the plant growth and obviously reduce the yield. The disease is caused by Colletotrichum spp. In Bali, Indonesia, six species of Colletotrichum have been identified: Colletotrichum scovillei, C. acutatum, C. nymphaeae, C. gloeosporioides, C. truncatum, and C. fructicola. However, among them the C. scovillei was found to be the most prevalent cause of anthracnose on chili pepper in Bali. Two species of antagonist against C. scovillei, namely Paenibacillus polymyxa C1 and Bacillus siamensis C7B, have been identified. In this study the effectiveness of P. polymyxa C1 formulation was evaluated under greenhouse condition on chili pepper cultivars Cabe Besar. Application of formulation was conducted by a mini hand sprayer once to five times with a week interval. Results of the study showed that treatment with five applications significantly (p < 0.05) reduced the disease incidence, disease intensity, and the yield loss of chili pepper cultivar Cabe Besar. Alose relationship was observed between the number of applications with disease intensity, with coefficient of determination (R2) at 0.929. These results revealed that the formulation of P. polymyxa C1 effectively control the anthracnose disease on chili pepper, particularly on chili pepper cultivar Cabe Besar, and thus can be recommended for field testing to confirm its stability under field conditions.

Antioxidant Activity of Antilisterial Bacteriocns Isolated from Paenibacillus polmyxa and Enterococcus faecium GRD AA

Anti-listerial bacteriocin producing strain was isolated, purified and characterized from fermented food source toddy and milk and found to be the genus Paenibacillus polymyxa and Enterococcus faecium GRD AA. The bacteriocins ALC101 and ALC102 were partially purified by Amberlite XAD-16 purification method and anti-listerial activity were checked. Both the bacteriocins ALC101 and ALC102 along with Nisin showed a maximum of 85% of DPPH and 85.5% of ABTS radical scavenging activity like BHT which was the standard used in the assay. The bacteriocins also showed a maximum of 87.6% Fe2+ reduction potential. From the results it can be concluded as bacteriocin produced by Paenibacillus polymyxa ALC101, and bacteriocin from Enterococcus faecium GRD AA ALC102 has a good antioxidant potential when compared to Nisin and BHT (positive control).

A probiotic based product using multi-strain Bacillus species and predictive models for shrimp growth following probiotic intervention

Probiotic bacteria in aquaculture found to have significant effect on health of shrimp and growth by changing the microbial composition of water. The primary objective of the study is to develop a probiotic based product to improve the yield of shrimp by using multi-strain Bacillus species. Towards this, various Bacillus strains, namely, B. subtilis, Bacillus clausii, B. cereus, B. Megaterium, B. pumilus and Bacillus polymyxa were collected and confirmed the strains through biochemical tests in subculture. Further, it is found that all the six strains exhibited good antifungal, antibacterial, antagonistic and enzyme activities. Multi-strain probiotic product as feed for the growth of shrimp was prepared by using the solid state fermentation technique and quality check was done to make sure no contamination. After the product development, the efficacy of the product has been tested by conducting field studies. The parameters such as (i) temperature (ii) pH (iii) dissolved oxygen (iv) total ammonia nitrogen and (v) shrimp weight & (vi) length were investigated for about 120 days and measurements were taken at every 5-day interval. The average initial weight and length of shrimp is 4.2 ± 0.2 g and 0.8 ± 0.1 cm respectively. The average values obtained for 120 days include (i) Temperature (°C): Control = 28 ± 0.3; Treated = 28 ± 0.15 (ii) pH: Control = 8 ± 0.19; Treated = 8 ± 0.12 (iii) Dissolved oxygen (ppm): Control = 5 ± 0.23, Treated = 5 ± 0.21 (iv) Total ammonia nitrogen (ppm): Control = 2 ± 0.2; Treated = 0.8 ± 0.01 (v) Shrimp weight (gm): Control = 16 ± 0.21; Treated = 22 ± 0.14 (vi) Length (cm): Control = 6 ± 0.14; Treated = 8 ± 0.26. The average survival rate was found to be 88.67 ± 1.15% in probiotics ponds and 70.00 ± 3.0% in controlled ponds. From the overall study, it is observed that the weight and length of shrimp has been increased significantly up to sixty days compared to control environment. Two-way ANOVA has been performed to understand the interdependent relation between the input and output variables. Advanced statistical models were developed by using the concepts of Artificial neural network, Multivariate adaptive regression splines and Relevance vector machine to predict the shrimp weight and length. The predicted shrimp weight and shrimp length is found to be in close agreement with those of the corresponding experimental observations. The models are found to be robust, reliable and efficient.

Preparation and efficacy evaluation of Paenibacillus polymyxa KM2501-1 microbial organic fertilizer against root-knot nematodes

Root-knot nematodes (RKNs) cause huge yield losses to agricultural crops worldwide. Meanwhile, livestock manure is often improperly managed by farmers, which leads to serious environmental pollution. To resolve these two problems, this study developed a procedure for the conversion of chicken manure to organic fertilizer by larvae of Hermetia illucens L. and Bacillus subtilis BSF-CL. Chicken manure organic fertilizer was then mixed thoroughly with Paenibacillus polymyxa KM2501-1 to a final concentration of 1.5×108 CFU g−1. The efficacy of KM2501-1 microbial organic fertilizer in controlling root-knot nematodes was evaluated in pot and field experiments. In pot experiments, applying KM2501-1 microbial organic fertilizer either as a base fertilizer or as a fumigant at the dose of 40 g/pot suppressed root-knot disease by 61.76 and 69.05% compared to the corresponding control treatments, respectively. When applied as a fumigant at the dose of 1 kg m−2 in field experiments, KM2501-1 microbial organic fertilizer enhanced the growth of tomato plants, suppressed root-knot disease by 49.97%, and reduced second stage juveniles of RKN in soil by 88.68%. KM2501-1 microbial organic fertilizer controlled RKNs better than commercial bio-organic fertilizer in both pot and field experiments. These results demonstrate that this co-conversion process efficiently transforms chicken manure into high value-added larvae biomass and KM2501-1 microbial organic fertilizer with potential application as a novel nematode control agent.

Antimicrobial activity of exometabolites of Paenibacillus polymyxa, isolated from endophytic community of winter wheat grain

In preliminary studies, a strain Paenibacillus polymyxa P6 possessing multiple plant growth-promoting (phosphate solubilization, oligonitrotrophy and production of heteroauxins) and antagonistic activities was isolated from grainresided cultivable bacterial endophytic community of winter wheat variety of the domestic selection Podolyanka with increased resistance to the causative agent of basal bacteriosis of grain crops Pseudomonas syringae pv. atrofaciens. The aim of this work was to study the antimicrobial effect of the exometabolites, produced by isolated strain, towards gram-negative phytopathogenic microorganisms using the method of deferred antagonism under the condition of cultivating the antagonistsc bacterium for 72 and 120 hours before inoculation of test cultures. Microorganisms stored in the collection of the D.K. Zabolotny Institute of Microbiology and Virology, NAS of Ukraine: Ralstonia solanocearum B-1109, Pectobacterium carotovora subsp. carotovora B-1077, Pseudomonas syringae pv. syringae B-1022, Pseudomonas syringae pv. syringae van Hall 1902 B-1027, Pseudomonas syringae pv. atrofaciens B-1011, Pseudomonas syringae pv. atrofaciens B-1013, as well as Erwinia amylovora ATCC 15580 were used as a test-cultures. Paenibacillus polymyxa P6 exometabolites were found to have a dose-dependent antimicrobial effect towards all studied microorganisms. The most pronounced inhibitory effect was registered against Erwinia amylovora ATCC 15580, Pseudomonas syringae pv. syringae B1022 and Ralstonia solanocearum B-1109: the diameter of the zone of no growth under the action of exometabolites produced for 120 hours are 25.72 ± 4.0 mm, 22.93 ± 2.0 mm and 20.30 ± 4.0 respectively. These results substantiate the expediency of further investigation of the composition and biological activity of the studied exometabolites in the perspective of developing biotechnological preparations.

Visualization and characterization of spore morphogenesis in Paenibacillus polymyxa ATCC39564.

Paenibacillus polymyxa is a spore-forming Gram-positive bacterial species. Both its sporulation process and the spore properties are poorly understood. Here, we investigated sporulation in P. polymyxa ATCC39564. When cultured at 37℃ for 24 h in sporulation medium, more than 80% of the total cells in the culture were spores. Time-lapse imaging revealed that cellular morphological changes during sporulation of P. polymyxa were highly similar to those of B. subtilis. We demonstrated that genetic deletion of spo0A, sigE, sigF, sigG, or sigK, which are highly conserved transcriptional regulators in spore forming bacteria, abolished spore formation. In P. polymyxa, spo0A was required for cell growth in sporulation medium, as well as for the initiation of sporulation. The sigE and sigF mutants formed abnormal multiple asymmetric septa during the early stage of sporulation. The sigG and sigK mutants formed forespores in the sporangium, but they did not become mature. Moreover, fluorescence reporter analysis confirmed compartment-specific gene expression of spoIID and spoVFA in the mother cell and spoIIQ and sspF in the forespore. Transmission electron microscopy imaging revealed that P. polymyxa produces multilayered endospores but lacking a balloon-shaped exosporium. Our results indicate that spore morphogenesis is conserved between P. polymyxa and B. subtilis. However, P. polymyxa genomes lack many homologues encoding spore-coat proteins that are found in B. subtills, suggesting that there are differences in the spore coat composition and surface structure between P. polymyxa and B. subtilis.

Effect of rhizobacteria Paenibacillus polymyxa KB and chelate complex of biogenic silicon on photosynthetic pigments and yield of corn grain

We used corn seeds from maize (Zea mays L.) of the Dnieper 196 SV hybrid to analyze pre-sowing seed bacterization and treatment with biogenic silicon that could be promising in growing maize hybrids. The chlorophyll content in the leaves of corn plants gradually increased in growth phases and reached its maximum in the phase of milky ripeness of grain under the presowing seeds bacterization with Paenibacillus polymyxa KB and seed treatment with Biogenic Silicon (BSi). The corn yield during both variants of seed treatment increased, exceeding the control by 28.8% and 23.4%, respectively. Both variants of presowing seed treatments are promising in the growth of maize hybrids.

Utilization of Cheese Acid Whey as a Medium for Efficient Production of Broad-Spectrum Antimicrobials by <i>Paenibacillus polymyxa</i> OSY–EC

Utilization of Cheese Acid Whey as a Medium for Efficient Production of Broad-Spectrum Antimicrobials by <i>Paenibacillus polymyxa</i> OSY–EC

Integrated application of plant growth promoting rhizobacteria and biochar improves salt tolerance in eggplant seedlings

A pot study was conducted to determine the effects of the combination of plant growth promoting rhizobacteria (PGPR) and biochar on the growth, physiological, and biochemical characteristics of eggplant seedlings under salinity stress. The greenhouse experiment included two salinity levels of NaCl [S0 (0 mM NaCl) and S1 (100 mM NaCl)], three biochar levels [B0 (non-biochar), B1 (5%) and B2 (10%)] and two PGPR [R0 (non-PGPR), R1 (combination of Bacillus megaterium TV-6D, Paenibacillus polymyxa KIN- 37, and Pantoea agglomerans RK92). Results showed that plant growth, relative leaf water content (LRWC), and chlorophyll content of eggplant seedlings decreased significantly, while malondialdehyde (MDA), hydrogen peroxide (H2O2), proline, sucrose and ABA content, and electrolyte leakage (EL) increased significantly with increase in salinity levels. Biochar and PGPR applications mitigated the negative influence of salinity stress on plant growth and physiological and biochemical characteristics of eggplant seedlings, enhancing chlorophyll content, plant nutrient element uptake, and antioxidant enzyme activity. The enhanced salinity tolerance due to biochar and PGPR applications could be associated with a significant reduction in Na and Cl uptake, MDA, H2O2 and EL and an increase in LRWC, chlorophyll content, antioxidant activity and plant nutrient element uptake. Therefore, it can be concluded that combining biochar and PGPR could be used to minimize the detrimental impacts of salinity stress conditions in eggplant seedlings.

CRISPR-Cas9-mediated Large Cluster Deletion and Multiplex Genome Editing in Paenibacillus polymyxa.

The use of molecular tools based on the clustered regularly interspaced short palindromic repeats-Cas (CRISPR-Cas) systems has rapidly advanced genetic engineering. These molecular biological tools have been applied for different genetic engineering purposes in multiple organisms, including the quite rarely explored Paenibacillus polymyxa. However, only limited studies on large cluster deletion and multiplex genome editing have been described for this highly interesting and versatile bacterium. Here, we demonstrate the utilization of a Cas9-based system to realize targeted deletions of four biosynthetic gene clusters in the range of 12-41 kb by the use of a single targeting sgRNA. Furthermore, we also harnessed the system for multiplex editing of genes and large genomic regions. Multiplex deletion was achieved with more than 80% efficiency, while simultaneous integration at two distantly located sites was obtained with 58% efficiency. The findings reported in this study are anticipated to accelerate future research in P. polymyxa and related species.