Potential Bioagent Research Articles

Pseudomonas thivervalensis K321, a promising and effective biocontrol agent for managing apple Valsa canker triggered by Valsa mali

Plant growth-promoting rhizobacteria (PGPR) have been reported to suppress various diseases as potential bioagents. It can inhibit disease occurrence through various means such as directly killing pathogens and inducing systemic plant resistance. In this study, a bacterium isolated from soil showed significant inhibition of Valsa mali. Morphological observations and phylogenetic analysis identified the strain as Pseudomonas thivervalensis, named K321. Plate confrontation assays demonstrated that K321 treatment severely damaged V. mali growth, with scanning electron microscopy (SEM) observations showing severe distortion of hyphae due to K321 treatment. In vitro twigs inoculation experiments indicated that K321 had good preventive and therapeutic effects against apple Valsa canker (AVC). Applying K321 on apples significantly enhanced the apple inducing systemic resistance (ISR), including induced expression of apple ISR-related genes and increased ISR-related enzyme activity. Additionally, applying K321 on apples can activate apple MAPK by enhancing the phosphorylation of MPK3 and MPK6. In addition, K321 can promote plant growth by solubilizing phosphate, producing siderophores, and producing 3-indole-acetic acid (IAA). Application of 0.2% K321 increased tomato plant height by 53.71%, while 0.1% K321 increased tomato fresh weight by 59.55%. Transcriptome analysis revealed that K321 can inhibit the growth of V. mali by disrupting the integrity of its cell membrane through inhibiting the metabolism of essential membrane components (fatty acids) and disrupting carbohydrate metabolism. In addition, transcriptome analysis also showed that K321 can enhance plant resistance to AVC by inducing ISR-related hormones and MAPK signaling, and application of K321 significantly induced the transcription of plant growth-related genes. In summary, an excellent biocontrol strain has been discovered that can prevent AVC by inducing apple ISR and directly killing V. mali. This study indicated the great potential of P. thivervalensis K321 for use as a biological agent for the control of AVC.

Bioprospecting of microbial agents and their metabolites as potential inhibitors of Phytophthora cinnamomi, the causal agent of avocado root rot

Phytophthora Root Rot (PRR) is one of the economically important diseases infecting avocado causing substantial yield losses worldwide. In this study, the root rot pathogen infecting avocado has been characterized and potential bioagents targeting PRR have been identified through molecular approaches. Field surveys revealed varying degrees of disease severity (54 %–17.5 %) and incidence (50 %–10 %) in Western Ghats of Tamil Nadu, India. The pathogen was isolated and identified as Phytophthora spp. based on morphology which depicted typical coralloid-type growth patterns. Besides, phylogenetic analysis with the ITS, ras-related protein and COX genes showed closed similarity with P. cinnamomi. The isolates showed significant variation in pathogenicity, with PC(TKI)-10 exhibiting the highest severity (70 %) developing typical symptoms. In vitro efficacy assays through dual-plate and volatiles revealed potential inhibitory effects of Trichoderma harzianum T (MP)-7 (81.11 %) and Bacillus amyloliquefaciens B (TI)-3 (76.67 %) against P. cinnamomi, and Scanning Electron Microscopy (SEM) provided insights into the antagonistic mechanisms, revealing physical interactions and enzymatic lysis of the pathogen by T (MP)-7 and B (TI)-3. Furthermore, Gas Chromatography-Mass Spectrometry (GC-MS) analysis identified bioactive compounds in the crude extracts of these bioagents, elucidating their metabolic pathways and potential modes of action against P. cinnamomi. Our findings highlights the importance of P. cinnamomi in avocado and the mechanism of fungal and bacterial bioagents in the sustainable management of the disease.

Identification of entomopathogenic nematodes in Hainan Province, China and their efficacy against Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is a notorious migratory pest native to tropical and subtropical America. It invaded China in 2018 and can reproduce annually in Hainan Province. Entomopathogenic nematodes (EPNs) have gained interest as potential bioagent due to as an alternative to conventional pesticides are EPNs. We isolated 19 EPNs out of 155 soil samples using the Galleria-baiting method. This was the first comprehensive survey of EPNs in Hainan Province. Phylogenetic analyses of the ITS and D2D3 expansion region of the 28S rDNA gene were performed, and 19 strains belonging to Steinernema aciari, Steinernema sp., Heterorhabditis sp., Oscheius sp., Oscheius myriophilus and O. amsactae were identified. It was shown that S. aciari 22,000 caused 100% and 96% mortality to the third and sixth instar larvae of S. frugiperda, respectively. When the pupae of S. frugiperda were exposed to S. aciari 22,000, the pupae died after emergence. Our study suggests S. aciari 22,000 is a promising indigenous biocontrol agent against S. frugiperda in the future. These findings underscore the importance of continued investigation into the potential of indigenous EPNs for sustainable management strategies of S. frugiperda in agricultural areas.

Protease enzymes from Pseudomonas fluorescens and Pseudomonas aeruginosa as potential bioagents against Pratylenchus loosi

Root lesion nematode of tea (Pratylenchus loosi) is one of the most dangerous and destructive pests in all areas of the world where tea grows. Rhizobacteria with nematicidal properties were screened using the soils of root lesion nematode-infected tea fields located in Guilan province, Iran. Effective bacteria were identified based on molecular and biochemical methods. Protease enzyme production was investigated on skim milk agar (1%) medium. The effects of temperature and pH on the amount of protease production by bacteria were investigated. Three protease inhibitors, namely PMSF, EDTA and 1,10-phenanthroline, were investigated. In total, 150 bacterial strains were isolated from tea rhizosphere using the spread-plating technique and nutrient agar medium, of which four bacterial isolates of Pseudomonas spp. had nematicidal properties in the range of 84.98% to 95.24%. Two of the bacterial isolates, RH25 (Pseudomonas aeruginosa) and RH37 (Pseudomonas fluorescens), had the largest clear zone of proteolysis on skim milk agar and were subjected to various biochemical tests. The influences of time (1 to 120 h), temperature (22 to 37°C) and pH (7.0 to 8.5) were investigated in the production of protease. The highest enzyme production was obtained from growing RH37 and RH25 on mineral medium when incubated at temperatures of 26°C and 30°C for 72 and 96 h and at initial pH values of 7.2 and 7.6, respectively. Proteases obtained from RH37 (P. fluorescens) belonged to the metalloprotease and serine protease families and the one produced by RH25 (P. aeruginosa) was a metalloprotease. According to the results of this research, the most effective control mechanism of these bacteria against nematodes is the production of bacterial protease. This mechanism can be exploited to control nematodes.

Production of Exopolysaccharides and İndole Acetic Acid (IAA) by Rhizobacteria and Their Potential against Drought Stress in Upland Rice.

Peatlands are marginal agricultural lands due to highly acidic soil conditions and poor drainage systems. Drought stress is a big problem in peatlands as it can affect plants through poor root development, so technological innovations are needed to increase the productivity and sustainability of upland rice on peatlands. Rhizobacteria can overcome the effects of drought stress by altering root morphology, regulating stress-responsive genes, and producing exopolysaccharides and indole acetic acid (IAA). This study aimed to determine the ability of rhizobacteria in upland rice to produce exopolysaccharides and IAA, identify potential isolates using molecular markers, and prove the effect of rhizobacteria on viability and vigor index in upland rice. Rhizobacterial isolates were grown on yeast extract mannitol broth (YEMB) medium for exopolysaccharides production testing and Nutrient Broth (NB)+L-tryptophan medium for IAA production testing. The selected isolates identify using sequence 16S rRNA. The variables observed in testing the effect of rhizobacteria were germination ability, vigour index, and growth uniformity. EPS-1 isolate is the best production of exopolysaccharides (41.6 mg/ml) and IAA (60.83 ppm). The isolate EPS-1 was identified as Klebsiella variicola using 16S rRNA sequencing and phylogenetic analysis. The isolate EPS-1 can increase the viability and vigor of upland rice seeds. K. variicola is more adaptive and has several functional properties that can be developed as a potential bioagent or biofertilizer to improve soil nutrition, moisture and enhance plant growth. The use of rhizobacteria can reduce dependence on the use of synthetic materials with sustainable agriculture.

Unveiling the Biocontrol Potential of Rhizoplane Bacillus Species against Sugarcane Fusarium Wilt through Biochemical and Molecular Analysis.

Biocontrol is regarded as a viable alternate technique for managing sugarcane wilt disease caused by Fusarium sacchari. Many fungal antagonists against F. sacchari, have been reported, but the potential of bacterial antagonists was explored to a limited extent, so the present study evaluated the antagonistic potential of rhizoplane Bacillus species and their mode of action. A total of twenty Bacillus isolates from the rhizoplane of commercially grown sugarcane varieties were isolated. The potential isolate SRB2 had shown inhibition of 52.30, 33.33, & 44.44% and SRB20 of 35.00, 33.15, & 36.85% in direct, indirect, and remote confrontation respectively against F. sacchari. The effective strains were identified as Bacillus inaquosorum strain SRB2 and B. vallismortis strain SRB20, by PCR amplification of 16S-23S intergenic region. The biochemical studies on various direct and indirect biocontrol mechanisms revealed the production of IAA, Protease, Cellulase, Siderophores, and P solubilization. The molecular analysis revealed the presence of antimicrobial peptides biosynthetic genes like fenD (Fengycin), bmyB (Bacyllomicin) ituC (Iturin) and spaS (Subtilin) which provided a competitive edge to these isolates compared to other Bacillus strains. Under greenhouse experiments, the sett bacterization with SRB2, significantly (P < 0.001) reduced the seedling mortality by > 70% followed by SRB20 in F. sacchari inoculated pots. The study revealed that the isolates B. inaquosorum SRB2 and B. vallismortis SRB20 can be used as potential bioagents against sugarcane Fusarium wilt.

Characterisation of Streptomyces sp. VNUA116 with strong antifungal activity against Fusarium oxysporum f.sp. cubense tropical race 4

Banana (Musa spp.) is one of the most important crops in the world. However, banana production worldwide is threatened by the wilt disease caused by Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4). Controlling this disease remains a challenge with conventional control methods, and scientists are searching for long-term, effective, and sustainable strategies. Streptomyces species are known as resources for producing bioactive compounds that represent promising bioagents to control soil-borne diseases. Here, we reported the characteristics of a Streptomyces strain, VNUA116, with strong antifungal activity against Foc TR4. The culture filtrate of the strain VNUA116 exhibited antifungal activities against Foc TR4 by inhibiting mycelial growth and spore germination. Interestingly, the strain VNUA116 also exhibited broad-spectrum antifungal activity against various common pathogenic fungi. Based on the morphological, biochemical, and molecular properties, the strain VNUA116 was identified as Streptomyces sp. In addition, Streptomyces sp.VNUA116 showed valuable productions of IAA, siderophore, and several hydrolytic enzyme activities. Moreover, the presence of the PKS-I and PKS-II genes in the genome of Streptomyces sp. VNUA116 suggests potential for the biosynthesis of bioactive substances. Our finding suggested that Streptomyces sp. VNUA116 could be a potential bioagent for controlling Fusarium wilt and other fungal diseases in bananas.

Microalgae: A potential bioagent for treatment of emerging contaminants from domestic wastewater

Water crisis around the world leads to a growing interest in emerging contaminants (ECs) that can affect human health and the environment. Research showed that thousands of compounds from domestic consumers, such as endocrine disrupting chemicals (EDCs), personal care products (PCPs), and pharmaceuticals active compounds (PhAcs), could be found in wastewater in concentration mostly from ng L−1 to μg L−1. However, generally, wastewater treatment plants (WWTPs) are not designed to remove these ECs from wastewater to their discharge levels. Scientists are looking for economically feasible biotreatment options enabling the complete removal of ECs before discharge. Microalgae cultivation in domestic wastewater is likely a feasible approach for removing emerging contaminants and simultaneously removing any residual organic nutrients. Microalgal growth rate and contaminants removal efficiency could be affected by various factors, including light intensity, CO2 addition, presence of different nutrients, etc., and these parameters could greatly help make microalgae treatment more efficient. Furthermore, the algal biomass harvests could be repurposed to produce various bulk chemicals such as sustainable aviation fuel, biofuel, bioplastic, and biochar; this could significantly enhance the economic viability. Therefore, this review summarizes the microalgae-based bioprocess and their mechanisms for removing different ECs from different wastewaters and highlights the different strategies to improve the ECs removal efficiency. Furthermore, this review shows the role of different ECs in biomass profile and the relevance of using ECs-treated microalgae biomass to produce green products, as well as highlights the challenges and future research recommendations.

Indication and identification of entomopathogenic nematodes Rhabditida: Steinernematidae, Heterorhabditidae (a review)

Goal. Of the study is to analyze the peculiarities of the use of methods aimed at detecting and identifying beneficial microorganisms for plant protection — entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae).&#x0D; Results. A review of methods commonly used in faunistic studies of entomopathogenic nematodes (Steinernematidae, Heterorhabditidae) is given here, discussing their advantages and limitation. A single standard for many of the methods discussed in this review does not currently exist, so different approaches are described whose effectiveness has been confirmed experimentally and is considered satisfactory. First of all, the methods of soil sampling and insect hosts sampling and techniques for isolation of entomopathogenic nematodes from different types of samples are described. The most important systematic features of entomopathogenic nematodes, approaches to their identification and the main methods required for routine species identification, primarily the production of micro specimens and their examination by light microscopy, are discussed below. Methods of electron microscopy, cross-breeding and molecular genetic studies of entomopathogenic nematodes are also described.&#x0D; Conclusions. The obtained data are of significant theoretical and practical importance, as they allow for an informed choice of the most optimal method of detecting and identifying entomopathogenic nematodes — potential bioagents against insect pests.

Assessing the potential of chitosan based coatings in modulation of bacteriome on tomato carposphere

Chitosan based edible fruit coatings are being considered today as an unconventional, ecofriendly and safe alternative of postharvest chemical treatments. The mechanism of action of chitosan coatings, like its antifungal nature or forming a barrier for transpiration and respiration, is already known. We intended to study the effect of the chitosan on natural carposphere microbiome, specifically on non-culturalable bacterial communities during storage to explore the prebiotic like nature of the chitosan based coatings. Hence the effect of coatings viz. CS (1% Chitosan), TL (Tulsi or Ocimum sanctum leaf, 1 g L-1 aqueous extract), and CS/TL mixed (2:1, 1% Chitosan and Tulsi leaf extract) was observed on coated tomato fruit. Metagenomic bacteriome analyses revealed that the untreated samples were comparatively rich epiphytic bacterial flora though the core microbiome was conserved in all the samples. Bacterial community in ripened tomato fruit (after 7 d) was mostly dominated by Acetobacter (49%) while on treatment of coatings genera like Lactobacillus, Weissella, Methylovoruse, Bacillus and Pseudomonas increased. These bacteria can act as potential bio agents in carposphere while the probiotic nature of genera as Lactobacillus or Weissella can also help in delaying the ripening of fruit. As this was a pilot study, more such studies are needed on microbial communities associated with fruits, their assembly and dynamics as well as the nature of their contribution to fruit quality and pathogen resistance during fruit ripening and storage.

Algicidal Activity and Microcystin-LR Destruction by a Novel Strain Penicillium sp. GF3 Isolated from the Gulf of Finland (Baltic Sea).

The present article focuses on a strain of ascomycete GF3 isolated from a water sample taken in the Gulf of Finland. Based on phylogenetic analysis data, the isolate was identified as Penicillium sp. GF3. The fungus GF3 demonstrates algicidal activity towards cyanobacteria (98-100%). The algicidal effect on green algae did not exceed 50%. The isolate GF3 exhibits an indirect attack mode by releasing metabolites with algicidal and/or lytic activity into the environment. Moreover, the strain Penicillium sp. GF3 is able to degrade MC-LR. After 72 h of GF3 cultivation, the MC-LR content was reduced by 34.1% and 26.7% at initial 0.1 μg/mL and 0.45 μg/mL concentrations, respectively. The high stress resistance of the GF3 to toxic MC-LR is provided by a 1.5-fold activation of catalase activity and a change in the reduced glutathione content. Additionally, during the MC-LR biotransformation, a MC-LR-GSH conjugate and linearized MC-LR were identified. The linearized MC-LR in the presence of fungi capable of degrading MCs was revealed for the first time. Using Daphnia magna as a bioindicator, it was shown that the MC-LR biotransformation led to the formation of less toxic intermediates. The toxicity of the fungal filtrate is reduced by five times compared to the abiotic control. Our findings enhance the understanding of the role that ascomycete fungi have as potential bioagents for cyanoHABs to control and detoxify water bodies.

Karakteristik Bakteri Endofit Akar Tanaman Kedelai Penghasil Hormon Tumbuh IAA

The increase in soybean production and productivity has become a significant focus in the effort to meet global food demands. The use of environmentally friendly agricultural technologies and practices is a vigorously pursued strategy. Endophytic bacteria are one of the potential bioagents that can stimulate plant growth. The ability of endophytic bacteria to synthesizing the plant hormone indole-3-acetic acid (IAA) can be an alternative in the effort to enhance soybean plant productivity and ensure long-term agricultural sustainability. The objective of this study is to analyze diversity and ability of endophytic bacteria isolated from soybean roots to produce IAA. This research was conducted through several stages, including the isolation of endophytic bacteria from soybean root, evaluating the isolates' ablity for IAA production, and characterizing potential isolates based on macroscopic and microscopic characteristics. This research indicated that a total of 11 endophytic bacteria isolates were obtained from soybean plant roots. Among them, four isolates, namely EAK4, EAK5, EAK6, and EAK8, demonstrated the capability to synthesizing IAA ranging from 35.46 to 44.56 ppm. These isolates showed various macroscopic and microscopic characteristics and hold promise as biological agents that promote planth growth.

Keragaman genetik cendawan entomopatogen Metarhizium anisopliae (Metsch.) berasal dari tanah pertanaman kelapa sawit berdasarkan penanda RAPD

Metarizhium anisopliae (Metsch.) adalah cendawan entomopatogen yang umum menyerang kumbang Oryctes rhinoceros (Linnaeus). Cendawan ini adalah salah satu yang berpotensi dalam mewujudkan pengelolaan hama berkelanjutan karena ramah terhadap lingkungan. Tujuan penelitian ini adalah mengisolasi cendawan M. anisopliae dari berbagai sampel tanah pertanaman kelapa sawit dan melihat keragaman genetiknya berdasarkan penanda random amplification of polymorphic DNA (RAPD). Metode yang dilakukan dalam penelitian ini adalah identifikasi M. anisopliae secara morfologi dan molekuler (ITS), dan pengujian keragaman genetik menggunakan penanda RAPD. Lima belas isolat M. anisopliae berasal dari lima belas perkebunan rakyat kelapa sawit di Sumatera Utara diuji keragaman genetiknya. Berdasarkan karakter morfologinya semua isolat diidentifikasi sebagai Metarhizium sp. Hasil sekuens dengan primer ITS menunjukkan semua isolat M. anisopliae yang yang berasal dari tanah memiliki homologi 85–99% dengan strains M. anisopliae dan M. brunneum rujukan dari database bank gen National Center Biotechnology Information (NCBI). Delapan primer RAPD menghasilkan 39 pita yang mana 38 pita (98,44%) dari pita tersebut polimorfik. Kisaran jarak genetik atau ketidaksamaan genetik antara isolat M. anisopliae adalah 0,051 sampai 0,520%. Analisis pengelompokan RAPD menggunakan metode Neighbour-Joining Tree yang membentuk tiga kelompok.

Isolation and characterization of halotolerant plant growth promoting rhizobacteria from mangrove region of Sundarbans, India for enhanced crop productivity.

Halotolerant plant growth promoting rhizobacteria (PGPR) are beneficial microorganisms utilized to mitigate the biotic and abiotic stresses in plants. The areas of Sundarban mangroves of West Bengal, India have been reported to be rich in halotolerant microflora, yet major area remains unexplored. The present study, therefore, aims to map down the region-specific native microbial community potent of salt tolerance, plant growth promoting (PGP) activity and antagonistic activity against fungal pathogens. Bacterial samples were isolated from the saline soil of the Sundarban mangroves. A total of 156 bacterial samples were isolated and 20 were screened for their salt tolerance potential. These isolates were characterised using morphological, biochemical, and molecular approaches. Based on 16s rRNA sequencing, they were classified into 4 different genera, including Arthrobacter sp. (01 isolate), Pseudomonas plecoglossicida (01 isolate), Kocuria rosea (01 isolate), and Bacillus (17 isolates). The halotolerant isolates which possessed plant growth promoting traits including phosphate, and zinc solubilization, indole acetic acid production, siderophore, and ammonia generation were selected. Further, the effect of two halotolerant isolates GN-5 and JR-12 which showed most prominent PGP activities was evaluated in pea plant under high salinity conditions. The isolates improved survival by promoting germination (36 to 43%) and root-shoot growth and weight of pea plant in comparison to non-inoculated control plants. In a subsequent dual culture confrontation experiment, both these halo-tolerant isolates showed antagonistic activities against the aggressive root rot disease-causing Macrophomina phaseolina (Tassi) Goid NAIMCC-F-02902. The identified isolates could be used as potential bioagents for saline soils, with potential antagonistic effect on root rot disease. However, further studies at the physiological and molecular level would help to delineate a detail mechanistic understanding of broad-spectrum defence against salinity and potential biotic pathogen.

Mycodiplosis sp.1: Potential Bioagent to Control Asian Soybean Rust, Phakopsora pachyrhizi Syd. &amp; P. Syd2, in Northeast Mexico

En el presente trabajo se reporta por primera vez el consumo de las uredosporas de Phakopsora pachyrhizi Sydow & P. Sydow por las larvas del género Mycodiplosis (Rübsaamen, 1885) en el cultivo de soya (Glicine max L. Merrill). El trabo de investigación se desarrolló en la variedad de soya Huasteca-700, con fecha de siembra del 30 de diciembre del 2020, en el Sitio Experimental Ébano (SEE), ubicado en Ébano, San Luis Potosí, México. En este cultivo, las larvas del género Mycodiplosis fueron registradas en los folíolos con lesiones irregulares color caféamarillento, café-rojizo o café oscuro a los 71, 78, 85, y 92 días después de la siembra (DDS). En las fechas de muestreo, las larvas del género Mycodiplosis se observaron alimentando de uredosporas de la roya asiática. El número mayor de larvas se registró a los 78 DDS (n = 180) respecto a los 71, 85, y 92 DDS. A los 71 y 78 DDS, las larvas se observaron en los folíolos con una severidad promedio de 1.44 y 2.8%. Mientras que, a las 85 y 92 DDS, larvas se observaron en los folíolos con una severidad promedio de 26.81 y 38.5%. El registro del consumo de uredosporas de roya asiática de la soya por las larvas del género Mycodiplosis es el primer reporte para México. Con base en este resultado, las larvas del género Mycodiplosis podrían ser parte de los agentes control biológico de roya asiática en el cultivo de soya.

Seed biopriming with potential bioagents influences physiological processes and plant defense enzymes to ameliorate sheath blight induced yield loss in rice (Oryza sativa L.).

Disease management with the use of conventional pesticides has emerged as a major threat to the environment and human health. Moreover, the increasing cost of pesticides and their use in staple crops such as rice is not economically sustainable. The present study utilized a combination of two commercial powder formulations of biocontrol agents, Trichoderma harzianum (Th38) and Pseudomonas fluorescens (Pf28) to induce resistance against sheath blight disease via seed biopriming in basmati rice variety Vasumati and compared the performance with systemic fungicide carbendazim. Sheath blight infection significantly increased the levels of stress indicators such as proline (0.8 to 4.25 folds), hydrogen peroxide (0.89 to 1.61 folds), and lipid peroxidation (2.4 to 2.6 folds) in the infected tissues as compared to the healthy control. On the contrary, biopriming with biocontrol formulation (BCF) significantly reduced the level of stress markers, and substantially enhanced the levels of defense enzymes such as peroxidase (1.04 to 1.18 folds), phenylalanine ammonia lyase (1.02 to 1.17 folds), lipoxygenase (1.2 to 1.6 folds), and total phenolics (74% to 83%) as compared to the infected control. Besides, improved photosynthesis (48% to 59%) and nitrate reductase activity (21% to 42%) showed a positive effect on yield and biomass, which compensated disease induced losses in bio-primed plants. Conversely, the comparative analysis of the efficacy levels of BCF with carbendazim revealed BCF as a potential and eco-friendly alternative for reducing disease impact and maintaining higher yield in rice under sheath blight infection.

Trichoderma pubescens Elicit Induced Systemic Resistance in Tomato Challenged by Rhizoctonia solani.

Rhizoctonia solani causes severe diseases in many plant species, particularly root rot in tomato plants. For the first time, Trichoderma pubescens effectively controls R. solani in vitro and in vivo. R. solani strain R11 was identified using the ITS region (OP456527); meanwhile, T. pubescens strain Tp21 was characterized by the ITS region (OP456528) and two genes (tef-1 and rpb2). The antagonistic dual culture method revealed that T. pubescens had a high activity of 76.93% in vitro. A substantial increase in root length, plant height, shoot fresh and dry, and root fresh and dry weight was indicated after applying T. pubescens to tomato plants in vivo. Additionally, it significantly increased the chlorophyll content and total phenolic compounds. The treatment with T. pubescens exhibited a low disease index (DI, 16.00%) without significant differences with Uniform® fungicide at a concentration of 1 ppm (14.67%), while the R. solani-infected plants showed a DI of 78.67%. At 15 days after inoculation, promising increases in the relative expression levels of three defense-related genes (PAL, CHS, and HQT) were observed in all T. pubescens treated plants compared with the non-treated plants. Plants treated with T. pubescens alone showed the highest expression value, with relative transcriptional levels of PAL, CHS, and HQT that were 2.72-, 4.44-, and 3.72-fold higher in comparison with control plants, respectively. The two treatments of T. pubescens exhibited increasing antioxidant enzyme production (POX, SOD, PPO, and CAT), while high MDA and H2O2 levels were observed in the infected plants. The HPLC results of the leaf extract showed a fluctuation in polyphenolic compound content. T. pubescens application alone or for treating plant pathogen infection showed elevated phenolic acids such as chlorogenic and coumaric acids. Therefore, the ability of T. pubescens to inhibit the growth of R. solani, enhance the development of tomato plants, and induce systemic resistance supports the application of T. pubescens as a potential bioagent for managing root rot disease and productivity increase of crops.

A novel fungus Penicillium canescens LS-4.2 with algicidal activity against the toxic cyanobacterium Microcystis aeruginosa

In this study, the fungus strain LS-4.2 isolated from the bottom sediments of Lake Lower Suzdalskoe was tested for its algicidal activity. We identified the strain LS-4.2 as Penicillium canescens summing its morphological characteristics with the reported DNA sequence. We revealed that the filtrate of a 7-day culture of the fungus suppressed the cell growth of toxic Microcystis aeruginosa. Our results showed that the filtrate caused rapid M. aeruginosa growth inhibition up to complete cell lysis recorded after 4 days. Living fungal mycelia did not suppress the growth of cyanobacterium. According to the results of this study we suppose that strain LS-4.2 may be a potential bioagent in the control of cyanobacterial blooms.

Psychotropic endophytes of cereals as potential bioagents

Creating new biopesticides for protecting agricultural crops and developing their application methods, which are among the priority areas of the agro-industrial complex, are inextricably linked with continuous observation of soil microbiocenosis, growing plants, and changes in agro-climatic conditions in a specific region. Plant endophytes are potentially active bioagents for creating new microbiological preparations for protecting winter crops, as well as agricultural produce during its storage period. In connection with this, the morphophysiological characteristics of six isolates of endophytic bacteria, isolated at low temperatures from winter cereal plants, were studied. The species affiliation of the strains was determined - five isolates belonged to the genus Pseudomonas and one to the genus Chryseobacterium. An assessment of the antagonistic activity of endophytes in relation to phytopathogens causing rot of agricultural produce was conducted.

Eukaryotic Microorganisms as Biological Factories for the Preparation of Metal Nanoparticles

The use of microorganisms as reducing and stabilizing agents in biogenic syntheses of metal nanoparticles is an attractive approach. There is a large number of potential bioagents able to yield big amounts of various biomolecules, and to prepare nanoparticles of diverse physicochemical properties. Microscopic fungi and algae are widely studied for the preparation of nanoparticles, mainly because of their ability to produce vast amounts of extracellular proteins, enzymes, and other metabolites that can actively participate in the metal reduction and also contribute to the nanoparticle stabilization. This results in highly stable metal nanoparticles with interesting properties that can be used, for example, as antimicrobial agents (especially Ag or Cu nanoparticles) or as catalysts. This review summarizes the main, promising representatives of microscopic fungi, yeasts, and algae used for the preparation of nanoparticles of various metals.