Priestia megaterium Metabolism: Isolation, Identification of Naringenin Analogues and Genes Elevated Associated with Nanoparticle Intervention.

The impact of gold nanoparticles (AuNPs) on the biosynthetic manipulation of Priestia megaterium metabolism where an existing gene cluster is enhanced to produce and enrich bioactive secondary metabolites has been studied previously. In this research, we aimed to isolate and elucidate the structure of metabolites of compounds 1 and 2 which have been analyzed previously in P. megaterium crude extract. This was achieved through a PREP-ODS C18 column with an HPLC-UV/visible detector. Then, the compounds were subjected to nuclear magnetic resonance (NMR), electrospray ionization mass spectrometry (ESI-MS), and Fourier-transform infrared spectroscopy (FT-IR) techniques. Furthermore, bioinformatics and transcriptome analysis were used to examine the gene expression for which the secondary metabolites produced in the presence of AuNPs showed significant enhancement in transcriptomic responses. The metabolites of compounds 1 and 2 were identified as daidzein and genistein, respectively. The real-time polymerase chain reaction (RT-PCR) technique was used to assess the expression of three genes (csoR, CHS, and yjiB) from a panel of selected genes known to be involved in the biosynthesis of the identified secondary metabolites. The expression levels of two genes (csoR and yijB) increased in response to AuNP intervention, whereas CHS was unaffected.

Biosynthesis of resveratrol by an endophytic Priestia megaterium PH3 via the phenylpropane pathway.

Resveratrol (RES) is a secondary metabolite synthesized by plants in response to environmental stress and pathogen infection, which is of great significance for the industrial production of RES by fermentation culture. In this study, we aimed to explore the biosynthesis pathway of RES and its key enzymes in the Priestia megaterium PH3, which was isolated and screened from peanut fruit. Through Liquid Chromatography-Mass Spectrometry (LC-MS) analysis, we quantified the RES content and distribution in the culture medium and determined that Priestia megaterium PH3 mainly secreted RES extracellularly. Furthermore, the highest production of RES was observed in YPD, yielding an impressive 127.46 ± 6.11 µg/L. By optimizing the fermentation conditions, we achieved a remarkable RES yield of 946.82 ± 24.74 µg/L within just 2 days, which represents the highest reported yield for a natural isolate produced in such a short time frame. Our investigation revealed that the phenylpropane pathway is responsible for RES synthesis in this bacterium, with cinnamate 4-hydroxylase (C4H) identified as the main rate-limiting enzyme. Overall, our findings highlight the robust RES production capabilities of Priestia megaterium PH3, offering novel insights and potential applications for bacterial fermentation in RES production. KEY POINTS: • RES synthesized by the bacterium was confirmed through the phenylpropane pathway. • The key rate-limiting enzyme for biosynthesis-RES is C4H. • RES reached 946.82 ± 24.74 µg/L after fermentation for 2 days.

Analysis of the Potassium-Solubilizing Priestia megaterium Strain NK851 and Its Potassium Feldspar-Binding Proteins.

Potassium-solubilizing bacteria are an important microbial group that play a critical role in releasing mineral potassium from potassium-containing minerals, e.g., potassium feldspar. Their application may reduce eutrophication caused by overused potassium fertilizers and facilitate plants to utilize environmental potassium. In this study, a high-efficiency potassium-solubilizing bacterium, named NK851, was isolated from the Astragalus sinicus rhizosphere soil. This bacterium can grow in the medium with potassium feldspar as the sole potassium source, releasing 157 mg/L and 222 mg/L potassium after 3 days and 5 days of incubation, respectively. 16S rDNA sequencing and cluster analysis showed that this strain belongs to Priestia megaterium. Genome sequencing further revealed that this strain has a genome length of 5,305,142 bp, encoding 5473 genes. Among them, abundant genes are related to potassium decomposition and utilization, e.g., the genes involved in adherence to mineral potassium, potassium release, and intracellular trafficking. Moreover, the strong potassium-releasing capacity of NK851 is not attributed to the acidic pH but is attributed to the extracellular potassium feldspar-binding proteins, such as the elongation factor TU and the enolase that contains potassium feldspar-binding cavities. This study provides new information for exploration of the bacterium-mediated potassium solubilization mechanisms.

Draft genome sequence of potato crop bacterial isolates and nanoparticles-intervention for the induction of secondary metabolites biosynthesis.

Introduction: Insights about the effects of gold nanoparticles (AuNPs) on the biosynthetic manipulation of unknown microbe secondary metabolites could be a promising technique for prospective research on nano-biotechnology. Aim: In this research, we aimed to isolate a fresh, non-domesticated unknown bacterium strain from a common scab of potato crop located in Saudi Arabia and study the metabolic profile. Methodology: This was achieved through genomic DNA (gDNA) sequencing using Oxford Nanopore Technology. The genomic data were subjected to several bioinformatics tools, including canu-1.9 software, Prokka, DFAST, Geneious Prime, and AntiSMASH. We exposed the culture of the bacterial isolate with different concentrations of AuNPs and investigated the effects of AuNPs on secondary metabolites biosynthesis using several analytical techniques. Furthermore, Tandem-mass spectrometric (MS/MS) technique was optimized for the characterization of several significant sub-classes. Results: The genomic draft sequence assembly, alignment, and annotation have verified the bacterial isolate as Priestia megaterium. This bacterium has secondary metabolites related to different biosynthetic gene clusters. AuNPs intervention showed an increase in the production of compounds with the molecular weights of 254 and 270 Da in a direct-dependent manner with the increase of the AuNPs concentrations. Conclusion: The increase in the yields of compound 1 and 2 concomitantly with the increase in the concentration of the added AuNPs provide evidences about the effects of nanoparticles on the biosynthesis of the secondary metabolites. It contributes to the discovery of genes involved in different biosynthetic gene clusters (BGCs) and prediction of the structures of the natural products.

Pangenome analyses of Bacillus pumilus, Bacillus safensis, and Priestia megaterium exploring the plant-associated features of bacilli strains isolated from canola.

Previous genome mining of the strains Bacillus pumilus 7PB, Bacillus safensis 1TAz, 8Taz, and 32PB, and Priestia megaterium 16PB isolated from canola revealed differences in the profile of antimicrobial biosynthetic genes when compared to the species type strains. To evaluate not only the similarities among B. pumilus, B. safensis, and P. megaterium genomes but also the specificities found in the canola bacilli, we performed comparative genomic analyses through the pangenome evaluation of each species. Besides that, other genome features were explored, especially focusing on plant-associated and biotechnological characteristics. The combination of the genome metrics Average Nucleotide Identity and digital DNA-DNA hybridization formulas 1 and 3 adopting the universal thresholds of 95 and 70%, respectively, was suitable to verify the identification of strains from these groups. On average, core genes corresponded to 45%, 52%, and 34% of B. pumilus, B. safensis, and P. megaterium open pangenomes, respectively. Many genes related to adaptations to plant-associated lifestyles were predicted, especially in the Bacillus genomes. These included genes for acetoin production, polyamines utilization, root exudate chemoreceptors, biofilm formation, and plant cell-wall degrading enzymes. Overall, we could observe that strains of these species exhibit many features in common, whereas most of their variable genome portions have features yet to be uncovered. The observed antifungal activity of canola bacilli might be a result of the synergistic action of secondary metabolites, siderophores, and chitinases. Genome analysis confirmed that these species and strains have biotechnological potential to be used both as agricultural inoculants or hydrolases producers. Up to our knowledge, this is the first work that evaluates the pangenome features of P. megaterium.

Pangenomes-identified singletons for designing specific primers to identify bacterial strains in a plant growth-promoting consortium.

BACKGROUND: The use of plant growth-promoting microorganisms represents a sustainable way to increase agricultural yields and plant health. Thus, the identification and tracking of these microorganisms are determinants for validating their positive effects on crops. Pangenomes allow the identification of singletons that can be used to design specific primers for the detection of the studied strains. OBJECTIVE: This study aimed to establish a strategy based on the use of whole-genome sequencing and pangenomes for designing and validating primer sets for detecting Bacillus cabrialesii TE3T, Priestia megaterium TRQ8, and Bacillus paralicheniformis TRQ65, a promising beneficial bacterial consortium for wheat. METHODS AND RESULTS: The identification of singletons of TE3T, TRQ8, and TRQ65 was performed by pangenomes using the Kbase platform and subsequently analyzed using BLAST®. The identified DNA regions were used for primer design in AlleleID version 7. Primers were validated by multiplex PCR using pure template DNA from each studied strain, combinations of two or three DNA from these strains, and DNA from agricultural soil samples enriched (and not) with the bacterial consortium. Here, we report the first design of primers capable of detecting and identifying the beneficial strains TE3T, TRQ8, and TRQ65. CONCLUSIONS: The use of pangenomes allowed the distinction of unique sequences that enables the design of primers for specific identification of the studied bacterial strains. This strategy can be widely used for the design of primer sets to detect other strains of interest for combating biopiracy, and commercial protection of biological products, among other applications.

The "beauty in the beast"-the multiple uses of Priestia megaterium in biotechnology.

Over 30 years, the Gram-positive bacterium Priestia megaterium (previously known as Bacillus megaterium) was systematically developed for biotechnological applications ranging from the production of small molecules like vitamin B12, over polymers like polyhydroxybutyrate (PHB) up to the in vivo and in vitro synthesis of multiple proteins and finally whole-cell applications. Here we describe the use of the natural vitamin B12 (cobalamin) producer P. megaterium for the elucidation of the biosynthetic pathway and the subsequent systematic knowledge-based development for production purposes. The formation of PHB, a natural product of P. megaterium and potential petro-plastic substitute, is covered and discussed. Further important biotechnological characteristics of P. megaterium for recombinant protein production including high protein secretion capacity and simple cultivation on value-added carbon sources are outlined. This includes the advanced system with almost 30 commercially available expression vectors for the intracellular and extracellular production of recombinant proteins at the g/L scale. We also revealed a novel P. megaterium transcription-translation system as a complementary and versatile biotechnological tool kit. As an impressive biotechnology application, the formation of various cytochrome P450 is also critically highlighted. Finally, whole cellular applications in plant protection are completing the overall picture of P. megaterium as a versatile giant cell factory. KEY POINTS: • The use of Priestia megaterium for the biosynthesis of small molecules and recombinant proteins through to whole-cell applications is reviewed. • P. megaterium can act as a promising alternative host in biotechnological production processes.

Bioconversion of glycerol into polyhydroxyalkanoates through an atypical metabolism shift using Priestia megaterium during fermentation processes: A statistical analysis of carbon and nitrogen source concentrations.

Polyhydroxyalkanoates (PHA) are bioplastics which are well known as intracellular energy storage compounds and are produced in a large number of prokaryotic species. These bio-based inclusions are biodegradable, biocompatible and environmental friendly. Industrial production of, short chain and medium chain length PHA, involves the use of microorganisms and their enzymes. Priestia megaterium previously known as Bacillus megaterium is a well-recognized bacterium for producing short chain length PHA. This study focuses to characterize this bacterium for the production of medium chain length PHA, and a novel blend of both types of monomers having enhanced properties and versatile applications. Statistical analyses and simulations were used to demonstrate that cell dry weight can be derived as a function of OD600 and PHA content. Optimization of growth conditions resulted in the maximum PHA production as: 0. 05 g. g-x. H-1, where the rate of PHA production was 0.28 g L-1. H-1 and PHA concentration was 4.94 g. L-1. This study also demonstrated FTIR to be a semi quantitative tool for PHA production. Moreover, conversion of scl-PHA to mcl-PHA with reference to time intermissions using GC-FID are shown.

Bacterial Lipopeptides Are Effective against Pear Fire Blight.

Fire blight, a devastating disease caused by Erwinia amylovora, poses a significant threat to pear and apple trees in Xinjiang province, China. In an effort to combat this pathogen, we isolated 10 bacteria from various components of apple and crabapple trees and conducted screenings to assess their ability to inhibit E. amylovora in vitro. Through biochemical tests and partial 16S rRNA gene sequencing, we identified two promising strains, Priestia megaterium strain H1 and Bacillus subtilis strain I2. These strains were then evaluated for their efficacy in biocontrol under controlled laboratory conditions, focusing on immature fruits and leaves. Remarkably, all selected antagonists exhibited the capability to reduce the severity of the disease on both fruit and leaves. P. megaterium strain H1 and B. subtilis strain I2 exhibited significant reductions in disease incidence on both immature fruits and leaves compared to the control. Specifically, on immature fruits, they achieved reductions of 53.39% and 44.76%, respectively, while on leaves, they demonstrated reductions of 59.55% and 55.53%, respectively. Furthermore, during the study, we detected the presence of lipopeptides, including surfactin, iturins, bacillomycin D, and fengycins, in the methanol extract obtained from these two antagonistic bacteria using thin-layer chromatography (TLC). Based on the results obtained, B. subtilis strain I2 and P. megaterium strain H1 exhibit considerable potential for controlling fire blight. However, further evaluation of their efficacy under natural field conditions is essential to validate their practicality as a biocontrol method.

Priestia megaterium ASC-1 Isolated from Pickled Cabbage Ameliorates Hyperuricemia by Degrading Uric Acid in Rats.

Pickled cabbage, a traditional fermented food rich in functional microorganisms, can effectively control hyperuricemia and gout. In this study, a Priestia megaterium ASC-1 strain with strong uric acid (UA) degradation ability was isolated from pickled cabbage. After oral administration for 15 days, ASC-1 was stably colonized in the rats in this study. ASC-1 significantly reduced UA levels (67.24%) in hyperuricemic rats. Additionally, ASC-1 alleviated hyperuricemia-related inflammatory response, oxidative stress, and blood urea nitrogen. Intestinal microbial diversity results showed that ASC-1 restored intestinal injury and gut flora dysbiosis caused by hyperuricemia. These findings suggest that P. megaterium ASC-1 may be used as a therapeutic adjuvant for the treatment of hyperuricemia.

Genomic analysis of acid tolerance genes and deciphering the function of ydaG gene in mitigating acid tolerance in Priestia megaterium.

Adverse environmental conditions, such as acid stress, induce bacteria to employ several strategies to overcome these stressors. These strategies include forming biofilms and activating specific molecular pathways, such as the general stress response (GSR). The genome of Priestia megaterium strain G18 was sequenced using the Illumina NextSeq 500 system, resulting in a de novo assembly of 80 scaffolds. The scaffolded genome comprises 5,367,956 bp with a GC content of 37.89%, and was compared to related strains using the MiGA web server, revealing high similarity to P. megaterium NBRC 15308 and P. aryabhattai B8W22 with ANI scores of 95.4%. Phylogenetic and ribosomal multilocus sequence typing (rMLST) analyses, based on the 16S rRNA and ribosomal protein-encoding alleles, confirmed close relationships within the P. megaterium species. Functional annotation identified 5,484 protein-coding genes, with 72.31% classified into 22 COG categories, highlighting roles in amino acid transport, transcription, carbohydrate metabolism, and ribosomal structure. An in-depth genome analysis of P. megaterium G18 revealed several key genes associated with acid tolerance. Targeted inactivation of the ydaG gene from SigB regulon, a general stress response gene, significantly reduced growth under acidic conditions compared to the wild type. qRT-PCR analysis showed increased ydaG expression in acidic conditions, further supporting its role in acid stress response. Microscopic analysis revealed no morphological differences between wild-type and mutant cells, suggesting that ydaG is not involved in maintaining cellular morphology but in facilitating acid tolerance through stress protein production. This research contributes to understanding the molecular mechanisms underlying acid tolerance in soil bacteria, P. megaterium, shedding light on potential applications in agriculture and industry.

The Complex GH32 Enzyme Orchestra from Priestia megaterium Holds the Key to Better Discriminate Sucrose-6-phosphate Hydrolases from Other ß-Fructofuranosidases in Bacteria.

Inulin is widely used as a prebiotic and emerging as a priming compound to counteract plant diseases. We isolated inulin-degrading strains from the lettuce phyllosphere, identified as Bacillus subtilis and Priestia megaterium, species hosting well-known biocontrol organisms. To better understand their varying inulin degradation strategies, three intracellular ß-fructofuranosidases from P. megaterium NBRC15308 were characterized after expression in Escherichia coli: a predicted sucrose-6-phosphate (Suc6P) hydrolase (SacAP1, supported by molecular docking), an exofructanase (SacAP2), and an invertase (SacAP3). Based on protein multiple sequence and structure alignments of bacterial glycoside hydrolase family 32 enzymes, we identified conserved residues predicted to be involved in binding phosphorylated (Suc6P hydrolases) or nonphosphorylated substrates (invertases and fructanases). Suc6P hydrolases feature positively charged residues near the structural catalytic pocket (histidine, arginine, or lysine), whereas other ß-fructofuranosidases contain tryptophans. This correlates with our phylogenetic tree, grouping all predicted Suc6P hydrolases in a clan associated with genomic regions coding for transporters involved in substrate phosphorylation. These results will help to discriminate between Suc6P hydrolases and other ß-fructofuranosidases in future studies and to better understand the interaction of B. subtilis and P. megaterium endophytes with sucrose and/or fructans, sugars naturally present in plants or exogenously applied in the context of defense priming.

Draft genome sequence of Priestia megaterium AB-S79 strain isolated from active gold mine.

We screened and isolated Priestia megaterium strain AB-S79 from active gold mine soil, then sequenced its genome to unravel its biosynthetic traits. The isolate with a 5.7-Mb genome can be utilized as a reference in genome-guided strain selection for metabolic engineering and other biotechnological operations.

The alternative coproporphyrinogen III oxidase (CgoN) catalyzes the oxygen-independent conversion of coproporphyrinogen III into coproporphyrin III.

Nature utilizes three distinct pathways to synthesize the essential enzyme cofactor heme. The coproporphyrin III-dependent pathway, predominantly present in Bacillaceae, employs an oxygen-dependent coproporphyrinogen III oxidase (CgoX) that converts coproporphyrinogen III into coproporphyrin III. In this study, we report the bioinformatic-based identification of a gene called ytpQ, encoding a putative oxygen-independent counterpart, which we propose to term CgoN, from Priestia (Bacillus) megaterium. The recombinantly produced, purified, and monomeric YtpQ (CgoN) protein is shown to catalyze the oxygen-independent conversion of coproporphyrinogen III into coproporphyrin III. Minimal non-enzymatic conversion of coproporphyrinogen III was observed under the anaerobic test conditions employed in this study. FAD was identified as a cofactor, and menadione served as an artificial acceptor for the six abstracted electrons, with a KM value of 3.95 µmol/L and a kcat of 0.63 per min for the substrate. The resulting coproporphyrin III, in turn, acts as an effective substrate for the subsequent enzyme of the pathway, the coproporphyrin III ferrochelatase (CpfC). Under aerobic conditions, oxygen directly serves as an electron acceptor, but is replaced by the more efficient action of menadione. An AlphaFold2 model of the enzyme suggests that YtpQ adopts a compact triangular shape consisting of three domains. The N-terminal domain appears to be flexible with respect to the rest of the structure, potentially creating a ligand binding site that opens and closes during the catalytic cycle. A catalytic mechanism similar to the oxygen-independent protoporphyrinogen IX oxidase PgoH1 (HemG), based on the flavin-dependent abstraction of six electrons from coproporphyrinogen III and their potential quinone-dependent transfer to a membrane-localized electron transport chain, is proposed.

UV protection and insecticidal activity of microencapsulated Vip3Ag4 protein in Bacillus megaterium.

In this study, secretable Vip3Ag4 protein was encapsulated in Bacillus megaterium and used for quantitative bioassays, in order to determine the UV photoprotective capacity of the cell, for preventing inactivation of the insecticidal activity of the protein. The non-encapsulated and purified protein was exposed to the UV light showing a LC50 of 518 ng/cm2 against Spodoptera littoralis larvae, whereas the exposed encapsulated protein exhibited 479 ng/cm2. In addition to the capability to accumulate Vip3 proteins for the development of novel insecticidal formulates, the B. megaterium cell has demonstrated to provide moderate protection against the deleterious action of UV light.

Biosynthesis and biocompatibility evaluation of zinc oxide nanoparticles prepared using Priestia megaterium bacteria.

The current study aimed to find an effective, simple, ecological, and nontoxic method for bacterial green synthesis of zinc oxide nanoparticles (ZnONPs) using the bacterial strain Priestia megaterium BASMA 2022 (OP572246). The biosynthesis was confirmed by the change in color of the cell-free supernatant added to the zinc nitrate from yellow to pale brown. The Priestia megaterium zinc oxide nanoparticles (Pm/ZnONPs) were characterized using UV-Vis spectroscopy, high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and zeta potential. The Pm/ZnONPs characterization showed that they have a size ranging between 5.77 and 13.9 nm with a semi-sphere shape that is coated with a protein-carbohydrate complex. An EDX analysis of the Pm/ZnONPs revealed the presence of the shield matrix, which was composed of carbon, nitrogen, oxygen, chlorine, potassium, sodium, aluminum, sulfur, and zinc. The results of the FTIR analysis showed that the reduction and stabilization of the zinc salt solution were caused by the presence of O-H alcohols and phenols, O=C=O stretching of carbon dioxide, N=C=S stretching of isothiocyanate, and N-H bending of amine functional groups. The produced ZnONPs had good stability with a charge of - 16.2 mV, as evidenced by zeta potential analysis. The MTT assay revealed IC50 values of 8.42% and 200%, respectively, for the human A375 skin melanoma and human bone marrow 2M-302 cell lines. These findings revealed that the obtained Pm/ZnONPs have the biocompatibility to be applied in the pharmaceutical and biomedical sectors.

Isolation and characterization of Priestia megaterium KD7 for the biological control of pear fire blight.

Erwinia amylovora is a plant pathogen that causes fire blight disease in Rosaceous plants, such as pear and apple. To develop an effective biocontrol method to suppress E. amylovora, a total of 16 bacteria were isolated from pear orchard soil in China and screened for antagonistic activity in vitro. Among them, 9 isolates that exhibited antagonistic activity against E. amylovora were identified, including Bacillus atrophaeus, Priestia megaterium (previously known as Bacillus megaterium) and Serratia marcescens based on the partial 16S rDNA sequence analysis and similarity search. The plate confrontation experiments showed that strain 8 (P. megaterium strain KD7) had strong antagonistic activity against E. amylovora. The methanolic extract from cell-free supernatant of strain KD7 displayed high antibacterial activities against E. amylovora. Furthermore, the active compounds of strain KD7 were separated by thin layer chromatography (TLC) and the amino acids were detected by the presence of a spot with retention factor (Rf) of 0.71. Next, three lipopeptides were identified with high-resolution mass spectrometry (HRMS), including C13-surfactin [M+H]+ at m/z 1008.14, C15-surfactin [M+H]+ at m/z 1036.50, and C14-iturin A [M+H]+ at m/z 1043.17. Strain KD7 showed multiple antibiotic resistance, such as ampicillin, erythromycin, penicillin and tetracycline. The detached pear leaves, twigs and fruits assay showed that both protective and curative action with strain KD7 had the ability to decrease the development of fire blight. Taken together, P. megaterium strain KD7 is a potential effective biocontrol agent against fire blight.

Antibiotic resistance gene-free probiont administration to tilapia for growth performance and Streptococcus agalactiae resistance.

Background and Aim: The rapid development of aquaculture as a major food sector is accompanied by challenges, including diseases that affect tilapia farming worldwide. One such infectious disease caused by Streptococcus agalactiae poses a serious threat to tilapia populations. Probiotics have emerged as a potentially safe preventive measure against S. agalactiae infection. However, antimicrobial resistance from antibiotic-resistant bacteria remains a concern because it can lead to the spread of resistant bacteria and serve as a reservoir of antibiotic-resistant genes in fishes and the surrounding environment. This study aimed to identify candidate probiotic bacteria capable of promoting tilapia growth, providing resistance to S. agalactiae infection, devoid of potential pathogenicity, and free from antibiotic resistance genes. Subsequently, the performance of these probiotic candidates in tilapia was evaluated. Materials and Methods: Lactococcus garvieae, Priestia megaterium, Bacterium spp., Bacillus megaterium, Bacillus subtilis, and Bacillus pumilus were examined to assess their antibacterial properties, hemolytic patterns, and antibiotic resistance genes. We used the specific primers tetA, tetB, tetD, tetE, tetO, tetQ, ermB, and qnrS that were used for antibiotic resistance gene detection. In vivo probiotic efficacy was evaluated by administering probiotic candidates in tilapia feed at a concentration of 1 × 106 colonies/mL/50 g of feed over a 60-day maintenance period. Resistance to S. agalactiae infection was observed for 14 days after the challenge test. Results: Lactococcus garvieae, P. megaterium, and Bacterium spp. were identified as promising probiotic candidates among the bacterial isolates. On the other hand, B. megaterium, B. subtilis, and B. pumilus carried resistance genes and exhibited a ß hemolytic pattern, rendering them unsuitable as probiotic candidates. The selected probiotic candidates (L. garvieae, P. megaterium, and Bacterium spp.) demonstrated the potential to enhance tilapia growth, exhibited no pathogenic tendencies, and were free from antibiotic resistance genes. Supplementation with L. garvieae and Bacterium spp. enhanced tilapia resistance to S. agalactiae infection, whereas P. megaterium supplementation showed an insignificant survival rate compared with controls after the challenge test period. Conclusion: Probiotics, particularly L. garvieae, P. megaterium, and Bacterium spp., enhance growth and resistance against S. agalactiae infection, without harboring antibiotic resistance genes. Selecting probiotic candidates based on antibiotic resistance genes is essential to ensure the safety of fish, the environment, and human health.

Complete genome sequence data of Priestia megaterium strain MARUCO02 isolated from marine mangrove-inhabited sediments of the Indian Ocean in the Bagamoyo Coast.

Priestia is a genus of biotechnologically important bacteria adapted to thrive in a wide range of environmental conditions including the marine sediments. Here, we screened and isolated a strain from the Bagamoyo marine mangrove-inhabited sediments and then employed whole genome sequencing to recover and define its full genome. De novo-assembly with Unicycler (v. 0.4.8) and annotation with Prokaryotic Genome Annotation Pipeline (PGAP) revealed that that its genome contains one chromosome (5,549,131 bp), with a GC content of 37.62%. Further analysis showed that the genome contains 5,687 coding sequences (CDS), 4 rRNAs, 84 tRNAs, 12 ncRNAs, and at least 2 plasmids (1,142 bp and 6,490 bp). On the other hand, antiSMASH-based secondary metabolite analysis revealed that the novel strain (MARUCO02) contains gene clusters for biosynthesis of MEP-DOXP-dependent versatile isoprenoids (eg. carotenoids), siderophores (synechobactin and schizokinen) and polyhydroxyalkanoates (PHA). The genome dataset also informs about the presence genes encoding enzymes required for generation of hopanoids, compounds that confer adaption to harsh environmental conditions including industrial cultivation recipes. Our data from this novel Priestia megaterium strain MARUCO02 can be used for reference and in genome-guided selection of strains for production of isoprenoids as well as industrially useful siderophores and polymers, amenable for biosynthetic manipulations in a biotechnological process.

Zinc solubilizing bacteria and their potential as bioinoculant for growth promotion of green soybean (Glycine max L. Merr.).

Zinc-solubilizing rhizobacteria can convert insoluble zinc to an accessible form and increase Zn bioavailability in soil, which help mitigate Zn deficiency in crops. In this work, 121 bacterial isolates were isolated from the rhizosphere soils of peanuts, sweet potatoes, and cassava, and their capability to solubilize Zn was evaluated using Bunt and Rovira's agar containing 0.1% ZnO and ZnCO3. Among these isolates, six showed high Zn solubilization efficiencies ranging from 1.32 to 2.84 and 1.93 to 2.27 on the medium supplemented with 0.1% ZnO and ZnCO3, respectively. In a quantitative analysis of soluble Zn in liquid medium supplemented with 0.1% ZnO, the isolate KAH109 showed the maximum soluble zinc concentration of 62.89 mg L-1. Among the six isolates, the isolate KAH109 also produced the most indole-3-acetic acid (IAA) at 33.44 mg L-1, whereas the isolate KEX505 also produced IAA at 17.24 mg L-1 along with showing zinc and potassium solubilization activity. These strains were identified as Priestia megaterium KAH109 and Priestia aryabhattai KEX505 based on 16S rDNA sequence analysis. In a greenhouse experiment conducted in Nakhon Pathom, Thailand the ability of P. megaterium KAH109 and P. aryabhattai KEX505 to stimulate the growth and production of green soybeans was examined. The results revealed that inoculation with P. megaterium KAH109 and P. aryabhattai KEX505 considerably increased plant dry weight by 26.96% and 8.79%, respectively, and the number of grains per plant by 48.97% and 35.29% when compared to those of the uninoculated control. According to these results, both strains can be considered as a potential zinc solubilizing bioinoculant to promote the growth and production yield of green soybeans.