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The Journal of General and Applied... Dec 2023Bacteria represent an attractive source for the isolation and identification of potentially useful microorganisms for lignin depolymerization, a process required for the...
Bacteria represent an attractive source for the isolation and identification of potentially useful microorganisms for lignin depolymerization, a process required for the use of agricultural waste. In this work, ten autochthonous bacteria isolated from straw, cow manure, and composts were characterized for potential use in the biodelignification of the waste. A comparison of the ability to degrade lignin and the efficiency of ligninolytic enzymes was performed in bacteria grown in media with lignin as a sole carbon source (LLM, 3.5g/L lignin-alkali) and in complex media supplemented with All-Ban fiber (FLM, 1.5g/L). Bacterial isolates showed different abilities to degrade lignin, they decreased the lignin concentration from 7.6 to 18.6% in LLM and from 11.1 to 44.8% in FLM. They also presented the activity of manganese peroxidase, lignin peroxidases, and laccases with different specific activities. However, strain 26 identified as Paenibacillus polymyxa by sequencing the 16S rRNA showed the highest activity of lignin peroxidase and the ability to degrade efficiently lignocellulose. In addition, P. polymyxa showed the highest potential (desirability ≥ 0.795) related to the best combination of properties to depolymerize lignin from biomass. The results suggest that P. polymyxa has a coordinated lignin degradation system constituted of lignin peroxidase, manganese peroxidase, and laccase enzymes.
PubMed: 38104982
DOI: 10.2323/jgam.2023.12.001 -
Applied and Environmental Microbiology Sep 2023WLY78, a N-fixing bacterium, has great potential use as a biofertilizer in agriculture. Recently, we have revealed that GlnR positively and negatively regulates the...
WLY78, a N-fixing bacterium, has great potential use as a biofertilizer in agriculture. Recently, we have revealed that GlnR positively and negatively regulates the transcription of the (trogen ixation) operon () in WLY78 by binding to two loci of the promoter according to nitrogen availability. However, the regulatory mechanisms of nitrogen metabolism mediated by GlnR in the genus remain unclear. In this study, we have revealed that glutamine synthetase (GS) and GlnR in WLY78 play a key role in the regulation of nitrogen metabolism. GS (encoded by within ) and GS1 (encoded by ) belong to distinct groups: GSI-α and GSI-β. Both GS and GS1 have the enzyme activity to convert NH and glutamate into glutamine, but only GS is involved in the repression by GlnR. GlnR represses transcription of under excess nitrogen, while it activates the expression of under nitrogen limitation. GlnR simultaneously activates and represses the expression of and in response to nitrogen availability. Also, GlnR regulates the expression of and . IMPORTANCE In this study, we have revealed that GlnR uses multiple mechanisms to regulate nitrogen metabolism. GlnR activates or represses or simultaneously activates and inhibits the transcription of nitrogen metabolism genes in response to nitrogen availability. The multiple regulation mechanisms employed by GlnR are very different from GlnR which represses nitrogen metabolism under excess nitrogen. Both GS encoded by within the operon and GS1 encoded by in WLY78 are involved in ammonium assimilation, but only GS is required for regulating GlnR activity. The work not only provides significant insight into understanding the interplay of GlnR and GS in nitrogen metabolism but also provides guidance for improving nitrogen fixation efficiency by modulating nitrogen metabolism.
PubMed: 37668407
DOI: 10.1128/aem.00139-23 -
Nature Communications Sep 2023The rhizosheath, or the layer of soil closely adhering to roots, can help plants to tolerate drought under moderate soil drying conditions. Rhizosheath formation is the...
The rhizosheath, or the layer of soil closely adhering to roots, can help plants to tolerate drought under moderate soil drying conditions. Rhizosheath formation is the result of poorly understood interactions between root exudates, microbes, and soil conditions. Here, we study the roles played by the soil microbiota in rhizosheath formation in barley (a dry crop). We show that barley rhizosheath formation is greater in acid soil than in alkaline soil, and inoculation with microbiota from acid soil enhances rhizosheath formation in alkaline soil. The rhizosheath-promoting activity is associated with the presence of Flavobacteriaceae and Paenibacillaceae bacteria that express genes for biosynthesis of indole-3-acetic acid (IAA, a common auxin), as determined by metagenomics and metatranscriptomics. Two bacterial strains isolated from rhizosheath (Chryseobacterium culicis and Paenibacillus polymyxa) produce IAA and enhance barley rhizosheath formation, while their IAA-defective mutants are unable to promote rhizosheath formation. Co-inoculation with the IAA-producing strains enhances barley grain yield in field experiments through an increase in spike number. Our findings contribute to our understanding of barley rhizosheath formation, and suggest potential strategies for crop improvement.
Topics: Hordeum; Bacteria; Desiccation; Indoleacetic Acids; Soil
PubMed: 37726263
DOI: 10.1038/s41467-023-40916-4 -
Plants (Basel, Switzerland) Jun 2023is a plant growth-promoting rhizobacteria (PGPR) that has significant biocontrol properties. Wheat sheath blight caused by is a significant soil-borne disease of wheat...
is a plant growth-promoting rhizobacteria (PGPR) that has significant biocontrol properties. Wheat sheath blight caused by is a significant soil-borne disease of wheat that causes significant losses in wheat production, and the biological control against the disease has received extensive attention. ZYPP18 was identified using morphological and molecular characterization. An antagonistic activity experiment verified that ZYPP18 inhibits the growth of on artificial growth media. A detached leaf assay verified that ZYPP18 inhibits the expansion of wheat sheath blight on the detached leaf. ZYPP18 has been found to possess plant growth-promoting properties, as well as the ability to solubilize phosphate and generate indole-3-acetic acid. Results from hydroponic experiments showed that wheat seedlings treated with ZYPP18 grew faster. Additionally, pot experiments and field experiments demonstrated that ZYPP18 effectively controls the occurrence of wheat sheath blight. ZYPP18 reduced the incidence of wheat sheath blight in wheat seedlings by 37.37% and 37.90%, respectively. The control effect of ZYPP18 on wheat sheath blight was 56.30% and 65.57%, respectively. These findings provide evidence that ZYPP18 is an effective biological factor that can control disease and promote plant growth.
PubMed: 37447065
DOI: 10.3390/plants12132504 -
Molecules (Basel, Switzerland) Nov 2023Glycosidases are essential for the industrial production of functional oligosaccharides and many biotech applications. A novel β-galactosidase/α-L-arabinopyranosidase...
Glycosidases are essential for the industrial production of functional oligosaccharides and many biotech applications. A novel β-galactosidase/α-L-arabinopyranosidase (PpBGal42A) of the glycoside hydrolase family 42 (GH42) from KF-1 was identified and functionally characterized. Using NPG as a substrate, the recombinant PpBGal42A (77.16 kD) was shown to have an optimal temperature and pH of 30 °C and 6.0. Using NPαArap as a substrate, the optimal temperature and pH were 40 °C and 7.0. PpBGal42A has good temperature and pH stability. Furthermore, Na, K, Li, and Ca (5 mmol/L) enhanced the enzymatic activity, whereas Mn, Cu, Zn, and Hg significantly reduced the enzymatic activity. PpBGal42A hydrolyzed NP-β-D-galactoside and NP-α-L-arabinopyranoside. PpBGal42A liberated galactose from β-1,3/4/6-galactobiose and galactan. PpBGal42A hydrolyzed arabinopyranose at C20 of ginsenoside Rb2, but could not cleave arabinofuranose at C20 of ginsenoside Rc. Meanwhile, the molecular docking results revealed that PpBGal42A efficiently recognized and catalyzed lactose. PpBGal42A hydrolyzes lactose to galactose and glucose. PpBGal42A exhibits significant degradative activity towards citrus pectin when combined with pectinase. Our findings suggest that PpBGal42A is a novel bifunctional enzyme that is active as a β-galactosidase and α-L-arabinopyranosidase. This study expands on the diversity of bifunctional enzymes and provides a potentially effective tool for the food industry.
Topics: Paenibacillus polymyxa; Lactose; Molecular Docking Simulation; Galactose; Glycoside Hydrolases; Cloning, Molecular; beta-Galactosidase; Hydrogen-Ion Concentration; Substrate Specificity; Paenibacillus
PubMed: 38005185
DOI: 10.3390/molecules28227464 -
International Journal of Molecular... Feb 2024Screening of with antagonistic effects on paddy mold pathogens to provide strain resources for biological control of mold in L. screening of isolates antagonistic...
Screening of with antagonistic effects on paddy mold pathogens to provide strain resources for biological control of mold in L. screening of isolates antagonistic towards from rhizosphere soil of healthy paddy; classification and identification of antagonistic strains by biological characteristics and 16S rDNA sequence analysis; transcriptome sequencing after RNA extraction from Bacillus-treated ; and extraction of inhibitory crude proteins of by ammonium sulfate precipitation; inhibitory crude protein and spp. were treated separately for and observed by scanning electron microscopy (SEM). An antagonistic strain of , named B7, was identified as by 16S rDNA identification and phylogenetic evolutionary tree comparison analysis. Analysis of the transcriptome results showed that genes related to secondary metabolite biosynthesis such as antifungal protein were significantly downregulated. SEM results showed that the mycelium of underwent severe rupture after treatment with and antifungal proteins, respectively. In addition, the sporocarp changed less after treatment with , and the sporangium stalks had obvious folds. B7 has a good antagonistic effect against and has potential for biocontrol applications of paddy mold pathogens.
Topics: Paenibacillus polymyxa; Antifungal Agents; Phylogeny; Antibiosis; Bacillus; DNA, Ribosomal; Paenibacillus; Aspergillus
PubMed: 38396880
DOI: 10.3390/ijms25042195 -
Microbial Biotechnology Mar 2024Paenibacillus polymyxa is a non-pathogenic, Gram-positive bacterium endowed with a rich and versatile metabolism. However interesting, this bacterium has been seldom...
Paenibacillus polymyxa is a non-pathogenic, Gram-positive bacterium endowed with a rich and versatile metabolism. However interesting, this bacterium has been seldom used for bioproduction thus far. In this study, we engineered P. polymyxa for isobutanol production, a relevant bulk chemical and next-generation biofuel. A CRISPR-Cas9-based genome editing tool facilitated the chromosomal integration of a synthetic operon to establish isobutanol production. The 2,3-butanediol biosynthesis pathway, leading to the main fermentation product of P. polymyxa, was eliminated. A mutant strain harbouring the synthetic isobutanol operon (kdcA from Lactococcus lactis, and the native ilvC, ilvD and adh genes) produced 1 g L isobutanol under microaerobic conditions. Improving NADPH regeneration by overexpression of the malic enzyme subsequently increased the product titre by 50%. Network-wide proteomics provided insights into responses of P. polymyxa to isobutanol and revealed a significant metabolic shift caused by alcohol production. Glucose-6-phosphate 1-dehydrogenase, the key enzyme in the pentose phosphate pathway, was identified as a bottleneck that hindered efficient NADPH regeneration through this pathway. Furthermore, we conducted culture optimization towards cultivating P. polymyxa in a synthetic minimal medium. We identified biotin (B7), pantothenate (B5) and folate (B9) to be mutual essential vitamins for P. polymyxa. Our rational metabolic engineering of P. polymyxa for the production of a heterologous chemical sheds light on the metabolism of this bacterium towards further biotechnological exploitation.
Topics: Paenibacillus polymyxa; Carbon; NADP; Oxidation-Reduction; Paenibacillus; Metabolic Engineering; Butanols
PubMed: 38529712
DOI: 10.1111/1751-7915.14438 -
Frontiers in Microbiology 2024In recent years, bacterial-based biocontrol agents (BCA) have become a new trend for the control of fungal diseases such as fusarium wilt that seriously threaten the...
In recent years, bacterial-based biocontrol agents (BCA) have become a new trend for the control of fungal diseases such as fusarium wilt that seriously threaten the yield and quality of cucumber, which are transmitted through infested soil and water. This study was set out with the aim of figuring the mechanism of the isolated rhizobacterial strain PJH16 in preventing f. sp. (). Biocontrol and growth-promoting experiments revealed that bacterial strain causes effective inhibition of the fungal disease through a significant growth-promoting ability of plants, and had activities of β-1,3-glucanase, cellulase, amylase and protease. It could produce siderophore and indole-3-acetic acid, too. Using the high-throughput sequencing tool PacBio Sequel II system and the database annotation, the bacterial strain was identified as PJH16 and contained genes encoding for presence of biofilm formation, antimicrobial peptides, siderophores and hydrolyases. From comparing data between the whole genome of PJH16 with four closely related strains, findings revealed markedly the subtle differences in their genome sequences and proposed new antifungal substances present in PJH16. Therefore, PJH16 could be utilized in bioengineering a microbial formulation for application as biocontrol agent and bio-stimulant, in the future.
PubMed: 38591040
DOI: 10.3389/fmicb.2024.1359263 -
Frontiers in Bioengineering and... 2024The demand for highly robust and metabolically versatile microbes is of utmost importance for replacing fossil-based processes with biotechnological ones. Such an...
The demand for highly robust and metabolically versatile microbes is of utmost importance for replacing fossil-based processes with biotechnological ones. Such an example is the implementation of DSM 365 as a novel platform organism for the production of value-added products such as 2,3-butanediol or exopolysaccharides. For this, a complete genome sequence is the first requirement towards further developing this host towards a microbial chassis. A genome sequencing project has just been reported for DSM 365 showing a size of 5,788,318 bp with a total of 47 contigs. Herein, we report the first complete genome sequence of DSM 365, which consists of 5,889,536 bp with 45 RNAs, 106 tRNAs, 5,370 coding sequences and an average GC content of 45.6%, resulting in a closed genome of 365. The additional nucleotide data revealed a novel NRPS synthetase that may contribute to the production of tridecaptin. Building on these findings, we initiated the top-down construction of a chassis variant of . In the first stage, single knock-out mutants of non-essential genomic regions were created and evaluated for their biological fitness. As a result, two out of 18 variants showed impaired growth. The remaining deletion mutants were combined in two genome-reduced variants which either lack the production of endogenous biosynthetic gene clusters (GR1) or non-essential genomic regions including the insertion sequence IS (GR2), with a decrease of the native genome of 3.0% and 0.6%, respectively. Both variants, GR1 and GR2, showed identical growth characteristics to the wild-type. Endpoint titers of 2,3-butanediol and EPS production were also unaffected, validating these genome-reduced strains as suitable for further genetic engineering.
PubMed: 38605990
DOI: 10.3389/fbioe.2024.1378873 -
Plants (Basel, Switzerland) Oct 2023Clubroot is one of the most serious soil-borne diseases on crucifer crops worldwide. Seed treatment with biocontrol agents is an effective and eco-friendly way to...
Clubroot is one of the most serious soil-borne diseases on crucifer crops worldwide. Seed treatment with biocontrol agents is an effective and eco-friendly way to control clubroot disease. However, there is a big challenge to inoculating the seed with bacterial cells through seed pelleting due to the harsh environment on the seed surface or in the rhizosphere. In this study, a method for microbial seed pelleting was developed to protect pak choi seedlings against clubroot disease. Typically, a biocontrol bacterium, ZF129, was encapsulated by the spray-drying method with gum arabic as wall material, and then pak choi seeds were pelleted with the microencapsulated ZF129 (ZF129m). The morphology, storage stability, and release behavior of ZF129 microcapsules were evaluated. Compared with the naked ZF129 cells, encapsulated ZF129 cells showed higher viability during ambient storage on pak choi seeds. Moreover, ZF129m-pelleted seeds showed higher control efficacy (71.23%) against clubroot disease than that of nonencapsulated ZF129-pelleted seeds (61.64%) in pak choi. Seed pelleting with microencapsulated biocontrol ZF129 proved to be an effective and eco-friendly strategy for the control of clubroot disease in pak choi.
PubMed: 37960058
DOI: 10.3390/plants12213702