Potential Biocontrol Research Articles

Diversity and functional assessment of indigenous culturable bacteria inhabiting fine-flavor cacao rhizosphere: Uncovering antagonistic potential against Moniliophthora roreri

The Peruvian Amazonian native cacao faces ongoing challenges that significantly undermine its productivity. Among them, frosty pod rot disease and cadmium accumulation result in losses that need for effective and environmentally safe strategies, such as those based on bacteria. To explore the biological resources in the cacao soil, a descriptive study was conducted to assess the diversity of culturable bacteria across three production districts in the Amazonas region: La Peca, Imaza, and Cajaruro. The study also focused on the functional properties of these bacteria, particularly those related to the major issues limiting cacao cultivation. For this purpose, 90 native bacterial isolates were obtained from the cacao rhizosphere. According to diversity analysis, the community was composed of 19 bacterial genera, with a dominance of the Bacillaceae family and variable distribution among the districts. This variability was statistically supported by the PCoA plots and is related to the pH of the soil environment. The functional assessment revealed that 56.8% of the isolates showed an antagonism index greater than 75% after 7 days of confrontation. After 15 days of confrontation with Moniliophthora roreri, 68.2% of the bacterial population demonstrated this attribute. This capability was primarily exhibited by Bacillus strains. On the other hand, only 4.5% were capable of removing cadmium, highlighting the biocontrol potential of the bacterial community. In addition, some isolates produced siderophores (13.63%), solubilized phosphate (20.45%), and solubilized zinc (4.5%). Interestingly, these traits showed an uneven distribution, which correlated with the divergence found by the beta diversity.Our results revealed a diverse bacterial community inhabiting the Amazonian cacao rhizosphere, showcasing crucial functional properties related to the biocontrol of M. roreri. The information generated serves as a significant resource for the development of further biotechnological tools that can be applied to native Amazonian cacao.

Secondary metabolites and transcriptomic analysis of novel pulcherrimin producer Metschnikowia persimmonesis KIOM G15050: A potent and safe food biocontrol agent

Metschnikowia persimmonesis, a novel endophytic yeast strain isolated from Diospyros kaki calyx, possesses strong antimicrobial activity. We investigated its potential use as an environmentally safe food biocontrol agent through genomics, transcriptomics, and metabolomics. Secondary metabolites were isolated from M. persimmonesis, followed by chemical structure elucidation, PUL gene cluster identification, and RNA sequencing. Pulcherrimin was isolated using 2 M NaOH, its structure was confirmed, and the yield was quantified. Biocontrol efficacy of M. persimmonesis on persimmon fruits and calyx was evaluated by assessing lesion diameter and disease incidence. Following compounds were isolated from M. persimmonesis co-culture with Botrytis cinerea and Fusarium oxysporum: fusaric acid, benzoic acid, benzeneacetic acid, 4-hydroxybenzeneacetic acid, 4-(-2-hydoxyethyl)-benzoic acid, cyclo (Leu-Leu), benzenemethanol, 4-hydroxy-benzaldehide, 2-hydroxy-4-methoxy-benzoic acid, 4-hydroxy-benzoic acid, lumichrome, heptadecanoic acid, and nonadecanoic acid. Exposing M. persimmonesis to different growth media conditions (with or without sugar) resulted in the isolation of five compounds: Tyrosol, Cyclo (Pro-Val), cyclo(L-Pro-L-Tyr), cyclo(Leu-Leu), and cyclo(l-tyrosilylicine). Differentially expressed gene analysis revealed 3264 genes that were significantly expressed (fold change ≥2 and p-value ≤0.05) during M. persimmonesis growth in different media, of which only 270 (8.27%) showed altered expression in all sample combinations with Luria–Bertani Agar as control. Minimal media with ferric ions and tween-80 triggered the most gene expression changes, with the highest levels of PUL gene expression and pulcherrimin yield (262.166 mg/L) among all media treatments. M. persimmonesis also produced a higher amount of pulcherrimin (209.733 mg/L) than Metschnikowia pulcherrima (152.8 mg/L). M. persimmonesis inhibited the growth of Fusarium oxysporum in persimmon fruit and calyx. Toxicity evaluation of M. persimmonesis extracts showed no harmful effects on the liver and mitochondria of zebrafish, and no potential risk of cardiotoxicity in hERG-HEK293 cell lines. Thus, M. persimmonesis can be commercialized as a potent and safe biocontrol agent for preserving food products.

Isolation and genome characterization of Paenibacillus polymyxa 188, a potential biocontrol agent against fungi.

In this work, we aimed to isolate marine bacteria that produce metabolites with antifungal properties. Paenibacillus polymyxa 188 was isolated from a marine sediment sample, and it showed excellent antifungal activity against many fungi pathogenic to plants (Fusarium tricinctum, Pestalotiopsis clavispora, Fusarium oxysporum, F. oxysporum f. sp. Cubense (Foc), Curvularia plantarum, and Talaromyces pinophilus) and to humans (Aspergillus terreus, Penicillium oxalicum, and Microsphaeropsis arundinis). The antifungal compounds produced by P. polymyxa 188 were extracted and analyzed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The complete genome sequence and biosynthetic gene clusters of P. polymyxa 188 were characterized and compared with those of other strains. A total of 238 carbohydrate-active enzymes (CAZymes) were identified in P. polymyxa 188. Two antibiotic gene clusters, fusaricidin and tridecaptin, exist in P. polymyxa 188, which is different from other strains that typically have multiple antibiotic gene clusters. Paenibacilluspolymyxa 188 was identified with numerous biosynthetic gene clusters, and its antifungal ability against pathogenic fungi was verified.

Study on biocontrol aspect of potential Alcaligenes faecalis against Fusarium sp.,Concept and Approach

The world is dealing with vivid pollutions which lead to the degradation of resources and human health. In soil, the yield of crops is enhanced by the rampant use of chemical pesticides and fertilizers. The fungicides are applied on a large scale on almost all crops to control fungal infection which is the primary cause of crop productivity loss globally. The chemical fungicides are nevertheless causing great harm to soil quality and human health as many fungal pathogens are resistant to these chemical fungicides and all applied in bulk. There is a huge need for the substitution of such fungicides by natural components. The work is just an attempt in this aspect only to glorify Alcaligenes faecalis as a natural substitute for chemical fungicides as its bio- remediating aspect is explored earlier. The least explored association of Alcaligenes faecalis with Fusarium sp. which could be a futuristic fungicide is represented. Fusarium sp. (mainly Fusarium oxysporum and Fusarium incarnatum) are quite pathogenic causing great loss to various plants and crops across the globe. They are altogether responsible for wilt, leaf spot and root rot diseases. Alcaligenes faecalis as a potent biocontrol agent is introduced here as this bacterium has plant growth- promoting features too. So, Alcaligenes faecalis could become a natural, futuristic and biological fungicide and fertilizer. The large-scale bioinoculant production with its specific carrier molecules needs to be explored.

Exploring the biocontrol potential of rocket (Eruca sativa) extracts and associated microorganisms against Verticillium wilt.

This study aimed to assess the impact of rocket (Eruca sativa) extract on Verticillium wilt in eggplants, explore rhizospheric microorganisms for disease biocontrol, and evaluate selected strains' induced systemic resistance (ISR) potential while characterizing their genomic and biosynthetic profiles. Rocket extract application led to a significant reduction in Verticillium wilt symptoms in eggplants compared to controls. Isolated microorganisms from treated soil, including Paraburkholderia oxyphila EP1, Pseudomonas citronellolis EP2, Paraburkholderia eburnea EP3, and P. oxyphila EP4 and EP5, displayed efficacy against Verticillium dahliae, decreasing disease severity and incidence in planta. Notably, strains EP3 and EP4 triggered ISR in eggplants against V. dahliae. Genomic analysis unveiled shared biosynthetic gene clusters, such as ranthipeptide and non-ribosomal peptide synthetase-metallophore types, among the isolated strains. Additionally, metabolomic profiling of EP2 revealed the production of metabolites associated with amino acid metabolism, putative antibiotics, and phytohormones. The application of rocket extract resulted in a significant reduction in Verticillium wilt symptoms in eggplants, while the isolated microorganisms displayed efficacy against V. dahliae, inducing systemic resistance and revealing shared biosynthetic gene clusters, with metabolomic profiling highlighting potential disease-suppressing metabolites.

Biocontrol potential of rhizospheric fungi against Rigidoporus microporus, the causal agent of white root rot disease in tea plants

White root rot disease (WRD), caused by Rigidoporus microporus, poses a serious threat to various tropical trees, resulting in substantial crop damage and even plant death. However, there is still a lack of information regarding WRD in tea plants. Due to soil-borne in nature, synthetic fungicide is not recommended to control WRD. Therefore, biocontrol using natural microorganisms found in the tea's rhizosphere has been explored as a potential solution. This study aimed to identify rhizospheric fungi of tea plants with antagonistic properties that can be used as a biocontrol agent against R. microporus. The study involved a field survey and laboratory works had been conducted in a tea plantation at Rancabali, West Java and the Phytopathology Laboratory, Faculty of Agriculture, Universitas Padjadjaran from March to October 2021. The disease incidence and severity were assessed in three blocks of land representing different topographic conditions of the plantation while antagonism tests were conducted using the completely randomized design and dual culture method. The results showed that the highest occurrence of WRD was in the central part of the hill with the disease incidence and severity of 70 and 50%, respectively. Thirteen fungal isolates were obtained from the rhizosphere of tea plants, all of which were found to inhibit the growth of R. microporus. These isolates belonged to the genera of Trichoderma, Gliocladium, Paecilomyces, Penicillium, Aureobasidium, Acremonium and Rhizopus. The considerable inhibition of R. microporus colony growth was performed by the isolates of Aureobasidium sp. (51.23%), Rhizopus sp. (50%), and Trichoderma sp. (43.96%). The results suggested that rhizospheric fungi of tea plants have the potential as biocontrol agents against R. microporus.

Microbial lipopeptides: their pharmaceutical and biotechnological potential, applications, and way forward.

As lead molecules, cyclic lipopeptides with antibacterial, antifungal, and antiviral properties have garnered a lot of attention in recent years. Because of their potential, cyclic lipopeptides have earned recognition as a significant class of antimicrobial compounds with applications in pharmacology and biotechnology. These lipopeptides, often with biosurfactant properties, are amphiphilic, consisting of a hydrophilic moiety, like a carboxyl group, peptide backbone, or carbohydrates, and a hydrophobic moiety, mostly a fatty acid. Besides, several lipopeptides also have cationic groups that play an important role in biological activities. Antimicrobial lipopeptides can be considered as possible substitutes for antibiotics that are conventional to address the current drug-resistant issues as pharmaceutical industries modify the parent antibiotic molecules to render them more effective against antibiotic-resistant bacteria and fungi, leading to the development of more resistant microbial strains. Bacillus species produce lipopeptides, which are secondary metabolites that are amphiphilic and are typically synthesized by non-ribosomal peptide synthetases (NRPSs). They have been identified as potential biocontrol agents as they exhibit a broad spectrum of antimicrobial activity. A further benefit of lipopeptides is that they can be produced and purified biotechnologically or biochemically in a sustainable manner using readily available, affordable, renewable sources without harming the environment. In this review, we discuss the biochemical and functional characterization of antifungal lipopeptides, as well as their various modes of action, method of production and purification (in brief), and potential applications as novel antibiotic agents.

Biocontrol mechanism of Bacillus siamensis sp. QN2MO-1 against tomato fusarium wilt disease during fruit postharvest and planting

Tomato fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (Fol) is a highly destructive disease, resulting in severe economic losses of global tomato production annually. An eco-friendly alternative to chemical fungicide using biological control agents (BCAs) is urgently needed. Here, Bacillus siamensis QN2MO-1 was isolated from Noli fruit and had a strong antagonistic activity against Fol in vitro and in vivo. Strain QN2MO-1 also exhibited a broad-spectrum antifungal activity against the selected 14 phytopathogenic fungi. The crude protein produced by strain QN2MO-1 could inhibit the spore germination of Fol and destroy the spore structure. It was closely related with the generation of chitinase and β-1,3-glucanase secreted by strain QN2MO-1. In a pot experiment, the application of B. siamensis QN2MO-1 effectively alleviated the yellowing and wilting symptoms of tomato plants. The disease index and incidence rate were decreased by 72.72% and 80.96%, respectively. The rhizospheric soil in tomato plants owed a high abundance of microbial community. Moreover, strain QN2MO-1 also enhanced the plant growth and improved the fruit quality of tomato. Therefore, B. siamensis QN2MO-1 will be explored as a potential biocontrol agent and biofertilizer.

Assessment of Endophytic Fungal Community in Palm Leaves and Their Biocontrol Potential

Microbial endophytes live asymptomatically within a host plant and contribute positively to its fitness. Endophytes associate ubiquitously with all plants examined so far and form an integral part of the host for processes such as nutrient uptake and stress response and traits like disease resistance. Well-characterized host–endophyte interaction models exist, but little is known about the microbiome of the monocot plant host, palm. In this study, we identified the endophytic fungal community associated with mule palm leaves with an objective to test their antagonist effects on lethal pathogens of palms. The leaflets of mule palms were sampled across five sites in Central and South Florida, and fungal endophytes were identified using culture-dependent (CD) and amplicon sequence-based culture-independent (CI) methods. Operational taxonomic units (OTUs) corresponding to phylum Ascomycota were identified by both approaches, whereas Basidiomycota were only detected using the CI method. Among the ascomycetes, a small (22%) overlap in the OTUs at the genus level was observed between the two methods, whereas the majority (64%) of OTUs were detected using the CI approach. In vitro cocultivation of endophytes with palm pathogens was observed to produce three distinct interaction phenotypes: inhibition zone, niche establishment, and overlapping growth. Eight endophytes capable of inhibiting fungal pathogen growth in vitro were also identified, suggesting a biocontrol potential for endophyte-derived secondary metabolites. A better understanding of the composition, assembly, and ecology of palm-associated microbial communities would eventually lead to healthy and resilient palms. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Isolation and characterization of Paenibacillus peoriae JC-3jx from Dendrobium nobile.

Dendrobium is a rich source of high-value natural components. Endophytic fungi are well studied, yet bacteria research is limited. In this study, endophytic bacteria from Dendrobium nobile were isolated using an improved method, showing inhibition of pathogens and growth promotion. JC-3jx, identified as Paenibacillus peoriae, exhibited significant inhibitory activity against tested fungi and bacteria, including Escherichia coli. JC-3jx also promoted corn seed rooting and Dendrobium growth, highlighting its excellent biocontrol and growth-promoting potential.

Biocontrol Potential of Sodin 5, Type 1 Ribosome-Inactivating Protein from Salsola soda L. Seeds.

Sodin 5 is a type 1 ribosome-inactivating protein isolated from the seeds of Salsola soda L., an edible halophytic plant that is widespread in southern Europe, close to the coast. This plant, known as 'agretti', is under consideration as a new potential crop on saline soils. Considering a possible defence role of sodin 5 in the plant, we report here its antifungal activity against different halophilic and halotolerant fungi. Our results show that sodin 5 at a concentration of 40 µg/mL (1.4 µM) was able to inhibit the growth of the fungi Trimmatostromma salinum (35.3%), Candida parapsilosis (24.4%), Rhodotorula mucilaginosa (18.2%), Aspergillus flavus (12.2%), and Aureobasidium melanogenum (9.1%). The inhibition observed after 72 h was concentration-dependent. On the other hand, very slight growth inhibition was observed in the fungus Hortaea werneckii (4.2%), which commonly inhabits salterns. In addition, sodin 5 showed a cytotoxic effect on the Sf9 insect cell line, decreasing the survival of these cells to 63% at 1.0 µg/mL (34.5 nM). Structural analysis of sodin 5 revealed that its N-terminal amino acid residue is blocked. Using mass spectrometry, sodin 5 was identified as a homologous to type 1 polynucleotide:adenosine glycosylases, commonly known as ribosome-inactivating proteins from the Amaranthaceae family. Twenty-three percent of its primary structure was determined, including the catalytic site.

Endophytic Fungi as Potential Bio-Control Agents of Soil-Borne Pathogen

Endophytic Fungi as Potential Bio-Control Agents of Soil-Borne Pathogen

First European Erwinia amylovora Lytic Bacteriophage Cocktails Effective in the Host: Characterization and Prospects for Fire Blight Biocontrol.

Fire blight, caused by the plant-pathogenic bacterium Erwinia amylovora, is a highly contagious and difficult-to-control disease due to its efficient dissemination and survival and the scarcity of effective control methods. Copper and antibiotics are the most used treatments but pose environmental and human health risks. Bacteriophages (phages) constitute an ecological, safe, and sustainable fire blight control alternative. The goal of this study was to search for specific E. amylovora phages from plant material, soil, and water samples in Mediterranean environments. A collection of phages able to specifically infect and lyse E. amylovora strains was generated from former fire blight-affected orchards in Eastern Spain. Following in vitro characterization, assays in immature fruit revealed that preventively applying some of the phages or their combinations delayed the onset of fire blight symptoms and reduced the disease's severity, suggesting their biocontrol potential in Spain and other countries. The morphological and molecular characterization of the selected E. amylovora phages classified them as members of the class Caudoviricetes (former Myoviridae family) and genus Kolesnikvirus. This study reveals Mediterranean settings as plausible sources of E. amylovora-specific bacteriophages and provides the first effective European phage cocktails in plant material for the development of sustainable fire blight management measures.

In vivo Evaluation of Botanicals and Bio-Agents against Web Blight (Rhizoctonia solani) of Mungbean (Vigna radiata)

Web blight, caused by the fungus Rhizoctonia solani, poses a significant threat to mungbean (Vigna radiata) production, leading to yield losses and economic repercussions. This study investigates the antifungal of botanical extracts and bio-agents in managing web blight in mungbean crops. A series of controlled experiments were conducted to assess the antifungal properties of selected botanicals and the biocontrol potential of specific microbial agents. Various extracts, including botanicals and bio-agents have been found effective for management of web blight of mungbean caused by R. solani. The present investigation was carried out on disease management through use of botanicals and bio-agents. The minimum disease incidence and maximum disease control was obtained in Garlic followed by Ginger, Neem, Onion, Tulsi, Clerodendron, Sadabahar, at 10% concentrations at 50 days after sowing in pot sown crop, Each treatments differed significantly from each other.

Bacillus velezensis LY7 promotes pepper growth and induces resistance to Colletotrichum scovillei

Anthracnose of pepper (Capsicum annuum L), caused by Colletotrichum scovillei, is one of the three major diseases of pepper that seriously impact yield and quality. As an alternative to the use of synthetic chemical pesticides, a variety of endophytic bacteria have been reported to be potential biocontrol agents with the ability to improve disease resistance and abiotic stress tolerance in host plants. However, the mechanisms of action by which these different bacterial biocontrol agents inhibit the onset and development of disease, in some cases, remains unclear. In the present study, the potential use of the endophytic bacterial strain Bacillus velezensis LY7, originally isolated from pepper leaves, as a biocontrol agent was evaluated. More specifically, the ability of LY7 to control anthracnose in pepper and promote growth was assessed in pot experiments in a greenhouse and in vitro assays. Results indicated that the use of B. velezensis LY7 enhanced the synthesis of jasmonic acid and other hormones in pepper plants, as well as increased disease resistance and plant growth. A 200 × dilution of LY7 fermentation broth reduced disease incidence up to 90.70 %, while also enhancing plant growth. The mechanism of action of LY7 was also evaluated. Results indicated that LY7 secreted an antibiotic protein possessing a cupin domain OS. RNA-sequence analysis of the transcriptome of C. scovillei at several timepoints after exposure to LY7 (24, 48, and 72 h) revealed the up- and down-regulation of several genes. More specifically, LY7 induced the expression of genes associated with biosynthesis pathways and transcription factors involved in anthracnose pathogenicity. Our results indicate that the LY7 strain of induces hormone synthesis in pepper plants that results in enhanced disease resistance and promotes growth, as well as enhances stress tolerance by enhancing antioxidant and defense-related enzyme activity. These results demonstrate the potential of using LY7 for the biocontrol of anthracnose in pepper plants.

Screening and evaluation of bacterial endophytes of cowpea [Vigna unguiculata (L.) Walp.] for plant growth promotion and biocontrol potential

Cowpea [Vigna unguiculata (L.) Walp], is a popular leguminous vegetable crop grown in the wetland fallows of Kerala, India. Web blight caused by Rhizoctonia solani has turned out to be a problem in cowpeas, leading to substantial yield loss. We isolated 22 endophytic bacteria from fodder cowpea var. Aiswarya and 16 from bush cowpea var. Bhagyalakshmi, and evaluated their plant growth promotion ability and potential for web blight pathogen suppression. Initially, the isolates were screened in vitro for their plant growth promotional traits and antagonism against R. solani. The potential isolates were identified as Bacillus subtilis, B. amyloliquefaciens and B. velezensis through 16S rDNA cataloguing. Plant growth-promoting traits like the production of IAA (Indole acetic acid), ammonia, phosphorus, and siderophore by the promising isolates were also investigated. B. amyloliquefaciens CBSE5 recorded the highest IAA (3.54 microgram/mL) and siderophore production. B. velezensis CBRE5 showed the highest ammonia (177.29 micro moles/mL) production and phosphate solubilization. In the in vivo assay, seed biopriming along with foliar application on 20 and 40 days after sowing, of a consortium of B. amyloliquefaciens CBSE5 and B. velezensis CBRE5 recorded maximum values for all growth parameters viz. shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, pod yield and number of pods per plant. The present study reports for the first time the use of endophytic Bacillus spp. isolated from cowpeas as plant growth-promoting bacteria, with biocontrol potential against the web blight pathogen R. solani.

Unleashing Bacillus species as versatile antagonists: Harnessing the biocontrol potentials of the plant growth-promoting rhizobacteria to combat Macrophomina phaseolina infection in Gloriosa superba

Charcoal rot caused by Macrophomina phaseolina is one of the most devastating diseases that cause severe yield loss in Gloriosa superba cultivation. Plant growth-promoting rhizobacteria (PGPR) are extensively harnessed as biocontrol agents due to their effectiveness in combating a wide array of plant pathogens through a multifaceted approach. The present study delved into the mechanisms underlying its ability to inhibit root rot pathogen and its capacity to promote plant growth in G. superba, commonly known as glory lily. PGPR isolated from the rhizosphere of glory lily were subjected to in vitro assessments using the dual plate technique. The isolated Bacillus subtilis BGS-10 and B. velezensis BGS-21 showed higher mycelial inhibition (61%) against M. phaseolina. These strains also promote plant growth by producing indole-3-acetic acid, siderophore, ammonia, amylase, cellulase, pectinase, xylanase, and lipase chemicals. Genome screening of BGS-10 and BGS-21 revealed the presence of antimicrobial peptide genes such as Iturin (ituD gene), surfactin (srfA and sfp genes) along with the mycolytic enzyme β-1,3-glucanase. Further, the presence of secondary metabolites in the bacterial secretome was identified through gas chromatography-mass spectrometry (GC/MS) analysis. Notably, pyrrolo[1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl), 9 H-pyrido[3,4-b] indole and L-leucyl-D-leucine exhibited the highest docking score against enzymes responsible for pathogen growth and plant cell wall degradation. Under glasshouse conditions, tuber treatment and soil application of talc-based formulation of B. subtilis BGS-10 and B. velezensis BGS-21 suppress the root rot incidence with a minimal disease incidence of 27.78% over untreated control. Concurrently, there was a notable induction of defense-related enzymes, including peroxidase (PO), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL), in glory lily. Therefore, it can be concluded that plant growth-promoting Bacillus strains play a significant role in fortifying the plant's defense mechanisms against the root rot pathogen.

Volatile organic compounds (VOCs) produced by indigenous Bacterium strain BS1727 as antifungal agents against Ganoderma boninense

Ganoderma boninense, the causative agent behind basal stem rot (BSR) disease in oil palm, instigated a pressing need for innovative and ecologically sustainable strategies to counter its impact. Biological control strategies, particularly employing bio-fungicides, have emerged as environmentally friendly alternatives for managing oil palm plant diseases. This study delved into harnessing the biocontrol potential of Indigenous bacterial isolate by investigating and evaluating its bioactive compounds of ethyl acetate extract with the capacity to suppress G. boninense growth in oil palm plants. Molecular identification was utilized to identify of bacterial isolate using 16S rRNA primers (5′- AGA GTT TGA TCC TGG CTC AG– 3′) and (5′- GGA TAC CTT GTT ACG ACT T– 3′). The agar well diffusion technique and scanning electron microscopy (SEM) were utilized to assess the inhibitory effects of bacterial ethyl acetate extract against G. boninense. A comprehensive analysis of the bacterial ethyl acetate extracts was conducted by gas chromatography - mass spectrometry (GC–MS). Molecular identification confirmed that the bacterial isolate was Bacterium strain BS1727. By employing SEM, the ethyl acetate extracts had influenced on G. boninense mycelial architecture. The exposure to the bacterial ethyl acetate extracts induced degradation and morphological distortion of the mycelial structure, serving as an indicator of its impact on the mycelium's structural modulation. Noteworthy, the spectrum of bioactive compounds was a subset of aromatic hydrocarbons, encompassing volatile organic compounds (VOCs). Based on GC–MS analysis, among the VOCs, acetic acid butyl ester and toluene showed the highest relative peak areas, 46.34 % for acetic acid butyl ester and 31.82 % for toluene, respectively. Ethylbenzene had a relative peak area of 5.4 %, 1,1,2-trichloroethane 4.41 %, and allyldimethyl (prop-1-ynyl) silane 3.17 %. The remaining compounds were 6-undecyl-5,6-dihydro-2H-pyran-2-one, 3-decen-5-one, 2-methyl-, and o-cymene, with the relative peak areas were below 1 %. These findings explained the inherent capacity of antifungal compounds as a viable strategy in inhibiting the growth of G. boninense.

Flavonoids from Citrus reticulata: Inhibitory activity against pathogenic fungi and biocontrol potential

The risks of synthetic fungicides propel a shift to biological plant disease control. Attention has been focused on screening plant secondary metabolites for plant-derived pesticides. Flavonoids are abundant and structurally diverse in citrus peels. The co-cultivation of four fungal pathogens with flavonoid extracts from the peels of Citrus reticulata unveiled a substantial inhibitory effect of these compounds, with polymethoxyflavones identified as the primary contributors. The microencapsulated citrus flavonoids using sodium alginate and gelatin showed 60% efficiency against cucumber wilt in potted seedlings, highlighting the potential of citrus flavonoids for biocontrol in field applications.

Biofertilizer and biocontrol properties of Stenotrophomonas maltophilia BCM emphasize its potential application for sustainable agriculture.

Microbial biofertilizers or biocontrol agents are potential sustainable approaches to overcome the limitations of conventional agricultural practice. However, the limited catalog of microbial candidates for diversified crops creates hurdles in successfully implementing sustainable agriculture for increasing global/local populations. The present study aimed to explore the wheat rhizosphere microbiota for microbial strains with a biofertilizer and biocontrol potential. Using a microbial culturing-based approach, 12 unique microbial isolates were identified and screened for biofertilizer/biocontrol potential using genomics and physiological experimentations. Molecular, physiological, and phylogenetic characterization identified Stenotrophomonas maltophilia BCM as a potential microbial candidate for sustainable agriculture. Stenotrophomonas maltophilia BCM was identified as a coccus-shaped gram-negative microbe having optimal growth at 37°C in a partially alkaline environment (pH 8.0) with a proliferation time of ~67 minutes. The stress response physiology of Stenotrophomonas maltophilia BCM indicates its successful survival in dynamic environmental conditions. It significantly increased (P <0.05) the wheat seed germination percentage in the presence of phytopathogens and saline conditions. Genomic characterization decoded the presence of genes involved in plant growth promotion, nutrient assimilation, and antimicrobial activity. Experimental evidence also correlates with genomic insights to explain the potential of Stenotrophomonas maltophilia BCM as a potential biofertilizer and biocontrol agent. With these properties, Stenotrophomonas maltophilia BCM could sustainably promote wheat production to ensure food security for the increasing population, especially in native wheat-consuming areas.