Colony Diameter Research Articles

A study on the potential of Bacillus thuringiensis AK08 to control pathogenic fungi associated with chili plant

Colletotrichum sp. and Fusarium sp. are significant fungal plant pathogen that affect chili plants. Various techniques are employed to manage the plant pathogens, including the application of biological agents such as Bacillus thuringiensis (Bt). This study aims to evaluate the efficacy of Bt AK08 in managing Colletotrichum sp. and Fusarium sp. Bt AK08 was subjected to dual-culturing experiments with the pathogens individually. Positive controls were employed in this study, consisting of Colletotrichum sp. and Fusarium sp. that were cultivated separately on pure potato dextrose agar. Propineb supplemented growth medium was serves as a negative control. The study involved the assessment of colony diameter of Colletotrichum sp. and Fusarium sp., as well as the evaluation of the antagonism activity exhibited by Bt AK08 through antibiosis activity and hyphal lysis. The findings indicated that Bt AK08 did not exhibit any antibiosis action since it did not result in a reduction in the colony diameter of the plant pathogenic fungus. However, we observed the breakdown of the hypha of the fungi. The present discovery suggests that Bt AK08 has promise as a potential agent for the management of Colletotrichum sp. and Fusarium sp. Hence, additional investigation is necessary to maximize its potential.

Interspecific competition affects spore germination and gametophore development of mosses

Background Interactions between moss species in their earliest growth stages have received little attention. To what extent interspecific competition or priority effects influence spore germination, protonemal development and gametophore emergence is unknown. We evaluated such effects in pairwise interaction between six common bryophyte species: Atrichum undulatum, Bryum argenteum, Ceratodon purpureus, Funaria hygrometrica, Hypnum cupressiforme, Leptobryum pyriforme Methods Interspecific interactions were assessed in vitro. Spores were sterilized and sown on agar plates in three treatments: 1) as single species cultures (controls), 2) as pairwise species cultures inoculated simultaneously, and 3) with a time lag of 20 days between species. Data on time needed for spore germination, germination rate, the time needed for gametophore differentiation, number of gametophores per germinated spore and average diameter of colonies were collected. We also performed spore germination tests in single-species cultures at the start and end of the study, as well as tests for density-dependency at spore germination and gametophore formation. Results We observed strong pairwise interactive effects when sowing spores of different species simultaneously or with a delay of 20 days. The results indicate that spore germination is often inhibited by interspecific competition. The first species has an advantage as compared to the later colonizing species, i.e., an apparent priority effect. Interspecific interactions were also evident during gametophore development and included both inhibition and facilitation. Conclusion We found pronounced differences in the relative performance of species in interaction with other species during spore germination and gametophore formation. Allelopathic effects are the most probable explanation for these observations. Our results under sterile lab conditions are likely to reflect processes that occur in the wild, governing biotic filtering and bryophyte community assembly during primary and secondary colonization.

Genome analysis of Pseudomonas strain 4B with broad antagonistic activity against toxigenic fungi.

Pseudomonas sp. 4B isolated from the effluent pond of a bovine abattoir was investigated as antifungal against toxigenic fungi. The complete genome of Pseudomonas 4B was sequenced using the Illumina MiSeq platform. Phylogenetic analysis and genome comparisons indicated that the strain belongs to the Pseudomonas aeruginosa group. In silico investigation revealed gene clusters associated with the biosynthesis of several antifungals, including pyocyanin, rhizomide, thanamycin, and pyochelin. This bacterium was investigated through antifungal assays, showing an inhibitory effect against all toxigenic fungi tested. Bacterial cells reduced the diameter of fungal colonies, colony growth rate, and sporulation of each indicator fungi in 10-day simultaneous growing tests. The co-incubation of bacterial suspension and fungal spores in yeast extract-sucrose broth for 48h resulted in reduced spore germination. During simultaneous growth, decreased production of aflatoxin B1 and ochratoxin A by Aspergillus flavus and Aspergillus carbonarius, respectively, was observed. Genome analysis and in vitro studies showed the ability of P. aeruginosa 4B to reduce fungal growth parameters and mycotoxin levels, indicating the potential of this bacterium to control toxigenic fungi. The broad antifungal activity of this strain may represent a sustainable alternative for the exploration and subsequent use of its possible metabolites in order to control mycotoxin-producing fungi.

Talaromyces mellisjaponici sp. nov., a xerophilic species isolated from honey in Japan.

Five isolates of a xerophilic Talaromyces species were obtained from honey in Japan. Molecular phylogenetic analysis based on a combined dataset for four regions (rRNA internal transcribed spacer, β-tubulin, calmodulin and RNA polymerase II second largest subunit) revealed that the strains formed an independent clade in section Trachyspermi, which is sister to Talaromyces affinitatimellis, Talaromyces basipetosporus and Talaromyces speluncarum. The strains and their relatives have different growth on creatine agar, yeast extract sucrose agar and dichloran 18 % glycerol agar, different branching patterns (mostly monoverticillate or biverticillate, less frequently divaricate or terverticillate), and different sizes and surface structures of conidia. Xerotolerance tests were also conducted using media adjusted to five different sucrose concentrations (0, 20, 40, 60 and 80 %). The colony diameters of the strains were larger than those of T. affinitatimellis, T. basipetosporus and T. speluncarum at each sucrose concentration. Altogether, the obtained morphological, molecular and physiological data allowed the proposal of Talaromyces mellisjaponici sp. nov. for this novel species, with NBRC 116048T as the type strain.

IN VITRO TEST OF DIFFERENT ANTIBIOTICS ON BACTERIAL AND FUNGAL CONTAMINANTS OF TISSUE-CULTURED 'SABA' BANANA (Musa balbisiana)

The study was conducted to test the efficacy of various antibiotics in 'Saba' banana cultivar and to find out the most effective treatment against bacterial and fungal contaminants of tissue- cultured 'Saba' banana meriplants. This was conducted at the laboratory of University of Southeastern Philippines, Tagum-Mabini Campus. This experiment was laid out in a Completely Randomized Design (CRD) with five treatments replicated three times. The treatments were: T1- Control; T2- Streptomycin (200mg/L); T3- Nystatin (1ml/L); T4- Streptomycin (200mg/L) + Nystatin (1ml/L); and T5- Benomyl (100mg/L). Data were analyzed using ANOVA and compared through HSD. Results of the in vitro test on the zone of inhibition (mm) showed that the growth of gram positive bacterium was inhibited by Streptomycin 200 mg per liter among the other treatments. In vitro test likewise showed that the colony diameter (mm) of Trichoderma sp. in Benomyl (chemical check) 200 mg per liter had the lowest increase in colony diameter among the other treatments.

Spatial distribution pattern of Rhizobium leguminosarum bv. vicieae across legume growing areas of Tigray region

Introduction: Several research findings stated that, faba bean had phenotypically diverse and symbiotically effective in Tigray, Ethiopia. However, limited researches were conducted in the region regarding biological nitrogen fixation with local varieties and races. Objective: To address the limitations Spatial Distribution Pattern of Rhizobium leguminosarum bv. Vicieae across legume growing areas of Tigray region was investigated. Methodology: A total of 112 root nodules with (107.9 average) nodules plant-1 were collected from 15 major faba bean growing districts of the region for isolation and characterization of indigenous root nodulating bacteria of the host plant. A serious of methods and procedures were undertaken to confirm the presumptive, eco-physiological and morphological characteristics of the isolated Rhizobium bacteria in triplicates. Results: All the tested isolates were presumptively gram -ve, raised, translucent and white in color, failed to grow on peptone glucose agar, keto lactose test and Hofer’s alkaline test. Phenotypically, 75% of the isolated candidates were appearing large mucoid and morphologically >80% of them were recorded more than 2mm colony diameter. Physiologically, 100 % of the isolates were grown well at a temperature range between 20℃ and 30℃, pH values between 6 and 8, and in the range of 0.1 and 2.5% (w/v) NaCl concentrations. In addition to this, a faba bean nodulating bacterium uses a broad range (90-100%) of carbohydrate utilization. The effectiveness of the candidates confirms 65%, 18.33%, 15% and 1.6% were recorded as highly effective, effective, less effective and ineffective. Moreover, the highest and lowest symbiotic effectiveness was scored 457% and 21% respectively.

Antifungal effectiveness of some essential oils and their mixtures against Fusarium oxysporum f.sp cubense that causes fusarium wilt disease of banana plants

Antifungal effectiveness of several essential oil botanical pesticides and their mixtures against the fungus Fusarium oxysporum f.sp. cubense (Foc) which causes fusarium wilt disease of banana plants in vitro, was conducted from March to July 2023. The aim of the study was to obtain an effective botanical pesticide formulation and the right concentration for controlling the Foc causing Fusarium wilt disease in banana plants. The study was arranged in a completely randomized design in factorials with three replications. The experiment was carried out using two methods: a) Suppressing colony diameter using Potato Dextrose Agar (PDA) medium, b). Suppressing colony biomass using Potato Dextrose Broth (PDB) medium. The treatment was the formulation of essential oil (F) botanical pesticides as the first factor; F1 (Cymbopogon flexuosus oils), F2 (C. nardus essential oils), F3 (Eugenia aromatica leaf essential oils), F4 (Cinnamomum burmanii leaf oils), F5 (F1+F2), F6 (F1+F3), F7 (F1+F4) and F8 (F2 +F3), F9 (F2+F4) and F10 (F3+F4) The level of concentration (C) as a second factor C1(1000 ppm) and C2(2000 ppm). The results showed that the F3 (E. aromatica leaf oils) treatment had the best antifungal activity against Foc. At a concentration of 2000 ppm inhibition of the diameter growth and colony biomass reached 100%, followed by the F1 treatment (C. flexuosus oils) up to 89.73% and 95.75%, the F2 treatment (C. nardus oils) reach 84.58% and 89.67% and the lowest antifungal activity is F4 (C. burmanii leaf oils) which only 77.08% and 84.50%. The best mixed formulations were F5(F1+ F3) and F8(F2 + F3), at the same concentration suppression of colony growth reaching 100%. In general, mixed essential oils formulation have shown to increase the effectiveness of the antifungal activities.

Wpływ zasolenia podłoża hodowlanego na wzrost grzybów entomopatogeniczych z rodzajów Beauveria i Metarhizium

The aim of the research was to determine the effect of increasing NaCl concentration (one of the important stress factors for crop plants) on the growth of entomopathogenic fungi of the genus Beauveria and Metarhizium in vitro. The influence of 1, 3, 5 and 15% NaCl con¬centration on the growth of colonies of four selected species of fungi Beauveria bassiana, Beauveria brongniartii, Metarhizium anisopliae and Metarhizium flavoviride was examined in laboratory conditions. Test concentrations were added to Sabouraud’s culture medium (SDA). Colony growth observations were made every 5 days until day 20, measuring the colony diameter in mm. The conducted research showed that the NaCl concentrations used in the experiment had a differential effect on the growth of colonies of the tested species of entomopathogenic fungi of the genus Beauveria and Metarhizium. A slight salinity of the culture medium (1% NaCl concentration), regardless of the date of observation, increased the growth of B. bassiana and B. brongniartii colonies and limited the growth of M. fla¬voviride. On the 20th day of observation, 3% salinity statistically significantly stimulated the growth of the B. bassiana and M. flavoviride strains. A higher concentration of NaCl limited the growth of the tested strains, with M. flavoviride showing the greatest resistance, which may indicate it as a species with a relatively high potential for resistance to salinity. 15% salinity completely inhibited the growth of all entomopathogenic fungi tested.

First report of Aspergillus welwitschiae causing maize ear rot in Serbia.

In recent years, countries in Southeast Europe are facing climate changes characterized by extreme hot weather, which contribute to the increased frequency of Aspergillus species. Because of these changes, Aspergillus parasiticus was isolated, for the first time, from maize grain in Serbia (Nikolic et al, 2018). The presence of black powdery mycelia on maize ears indicated occurrence of species of the genus Aspergillus section Nigri, which led to the need for detailed identification of these fungi. Disease incidence ranged from 10 and 15% in August 2013. Maize ears with black powdery symptoms were collected from field in Zemun Polje, Serbia. Symptomatic kernels were surface sterilized with 1% sodium hypochlorite solution for 3 min, rinsed three times with sterilized water, then incubated at 25°C in the dark for 7 days on potato dextrose agar (PDA). Twenty isolates were identified as genus Aspergillus section Nigri. Monospore cultures formed black cottony colonies with a yellowish border on PDA. The average colony diameter was 50 mm. In order to reliably identify, isolates were transferred to Malt Extract agar (MEA) and Czapek Yeast Autolysate agar (CYA) (Samson et al, 2014). On CYA fungal colonies consisted of a white mycelium, covered by a layer of black conidiophores. On MEA fungal colonies were dense, black, with yellowish border. The reverse side was colorless to pale yellow, with a yellow ring in the middle. The average size of conidia was 4.3 µm. The conidia were globose to sub-globose, smooth to roughened, which coincides with previous research (Silva et al, 2020). Given that the fungi Aspergillus niger and Aspergillus welwitschiae are morphologically indistinguishable (Susca et al, 2016), species level identification was completed by analysis of a partial sequence of the internal transcribed spacer (ITS) region (ITS1/ITS4 primers) and calmodulin gene (CMD5/CMD6 primers) (Samson et al., 2014). The sequences were compared with the sequences of A. welwitschiae strains registered in the GenBank database based on nucleotide similarity, and results showed 99,64 and 100% similarity with ITS (OL711714) and calmodulin (KX894585), respectively. The sequence was deposited in GenBank with accession numbers OQ456471 (ITS) and OQ426518 (calmodulin). We also confirmed the presence of this species with specific primers (AWEL1/AWEL2) designed by Susca et al. 2020. Pathogenicity test was performed in Zemun Polje on the same maize hybrid from which the fungal species was isolated. Using artificial inoculations by the injecting conidial suspension into the silk channel, three days after 50% of plants reached the silking stage. Twenty ears were inoculated with each isolate, in four replicates (Reid et al, 1996). Inoculum was prepared from 7-day-old colonies on PDA, and 2 ml of a conidial suspension (1×106 spores/ml) was used. Control plants were inoculated with sterile water. All inoculated ears showed symptoms, similar to those from field infections. Control ears were symptomless. The fungus was reisolated and was morphologically identical to the original isolates, thus completing Koch's postulates. Based on molecular, morphological and pathogenic properties, the isolates were identified as A. welwitschiae. This is the first report of A. welwitschiae as the causal agent of black maize ear rot not only in Serbia, but also in the other countries of the Western Balkans. Given that the fungus A. welwitschiae synthesizes both ochratoxin A (OTA) (Battilani et al, 2006) and fumonisin (FB) (Frisvad et al, 2011), further studies should be focused on assessment its aggressiveness and toxicological profile.

Biodegradation of Low-Density Polyethylene (LDPE) by Aspergillus niger

The current study focused on the ability of Aspergillus niger to biodegrade low-density polyethylene, while studying some of the factors affecting the biodegradation process, including pH and temperature. Samples were collected from the soil of the waste landfill (sanitary landfill) of Dhi Qar Governorate, located 20 kilometers south of the center of the governorate, and using the dilution method. The genus Aspergillus niger had the highest appearance rate, reaching 100%, as it appeared in all samples, and the colony diameters in the solid medium were calculated. The fungus showed the ability to adapt and grow in the medium containing low-density polyethylene, with the a concentration of (0.1, 0.5, 1)%, and temperature of (15, 25, 35) ᵒC, also pH (2, 4, 6), and the addition of a carbon source of glucose, maltose and a nitrogen source (NH4Cl, NaNo3), the decomposition metabolites and the remaining concentration were identified by using Fourier – transform Infrared Spectroscopy and Gas – Mass Spectroscopy, and later a confirmatory test was conducted to determine the ability of Aspergillus niger to biodegrade low-density polyethylene in the medium of mineral salts.

Isolation, Identification and Screening of Humic Acid Producing Fungi from Soil Environment of Oil palm (Elaeisguineensis) Associated with Empty Fruit Bunches

The demand for sustainable and sustainable biotechnological processes has developed as a result of a growing interest in converting agricultural waste into valuable products. In this study, fungal strainswere isolated from soil environment ofoil palm empty fruit bunchesandscreened for humic acid production. In Osun state, Nigeria, soil sample was taken from a local palm oil mill. Different colonies of fungi were obtained for further research using the serial dilution plating procedure. Plate screening was used to evaluate the fungal biomass as well as colony diameter of the fungal isolates, and a submerged fermentation test was used to measure the amount of humic acid concentration the isolates produced. Fungal isolates were identified by using molecular methods and morphological analysis. The fungi species Aspergillusniger, Rhizopusstolonifer, and Penicilliumchrysogenum were isolated from the soil environment. When compared to Rhizopusstolonifer, Aspergillusniger grew more superiorly in terms of zone diameter (26.5 1.50 mm) and biomass (2.23 0.16 g), while Penicilliumchrysogenum showed no growth. Throughout the fermentation process, Aspergillusnigeralso produced a greater quantity of humic acid, with concentrations varying from 0.70 mg/l to 2.20 mg/l. Aspergillusniger strain HR18's existence was confirmed by molecular analysis. This experiment proved that Aspergillusniger can efficiently produce humic acid from OPEFB, providing a useful method for waste utilization and sustainable practices.

Green Synthesis of Silver Nanoparticles by Fusarium oxysporum and its Function Against Aspergillus and Fusarium Fungi.

(NPs) can be produced by various methods such as physical and chemical processes. However, environmentally friendly ways are increasingly requested. In this research, (Ag-NPs) were produced by Fusarium oxysporum, and its antifungal effect on Aspergillus and Fusarium was investigated. Nanoparticles were produced by silver nitrate salt and Fusarium oxysporum native to Isfahan city. In order to optimize the synthesis conditions, optimization of some factors such as volume, concentration, time, temperature, and pH of the extract was performed. The structural and physical properties of NPs were determined by spectrophotometer, XRD, FTIR FESEM, SEM, and TEM microscopy. For the study of the inhibitory effect of NPs on Fusarium and Aspergillus growth, the fungi were cultured in media containing various concentrations of NPs from 50 to 1500ppm. Then, the colony diameter was measured for over 10days and the growth inhibition percentage was estimated. For statistical analysis, the 600 Mann-Whitney tests have been applied.The NPs were produced after mixing the powdered fungal mass and silver nitrate salt in optimum conditions which were 2mM of salt, triple fungal mass volume proportion relative to the salt, pH of 9, and temperature of 28°C. The existence of a peak at 420nm in FTIR was due to nanoparticle production. Based on the XRD, the synthesized NPs had suitable properties similar to the standard NPs reported in the studies. Images from TEM, SEM, and FESEM microscopes displayed uniform NPs in variable sizes between 25 and 100nm. According to the results, the maximum growth inhibition percentage of Ag-NPs on Fusarium was approximately 60% at 1500ppm, and 88% on Aspergillus at 800ppm. Biosynthesized Ag-NPs with Fusarium oxysporum have desirable structural traits and can inhibit the growth of Fusarium and Aspergillus at significant levels.

Potencial of Rice Bran Extract as a Basic Ingridient in Candida albicans Culture Media

Rice bran is a natural material that contains nutrients that serves as a fungal growth factor, can be used as an alternative media base for fungal growth. The aim of this research is to determine the potential of rice bran as an alternative medium for the growth of Candida albicans. The research design employed an experiment that compared the growth of Candida albicans on rice bran extract media and Sabouraud Dextrose Agar (SDA) media. The sample is rice bran powder obtained from rice mills and rice bran extract was made using a multi-stage pretreatment method. The rice bran extract was used to create Rice bran Agar (RBA) and Rice bran Liquid (RBC) media, while SDA dan (SDB) media were also prepared. The media were inoculated with Candida albicans, incubated, and observed for 5 days. Data analysis included the measurement of fungal colony diameter using One Way Anova and Candida albicans biomass using an independent t-test. The research findings indicate that the average diameter of fungal colonies on RBA extract media was 10.4 mm, whereas it was 12.3 mm on SDA media. The Anova and Post Hoc Tukey HSD results demonstrated significant daily differences in colony diameter on RBA media, indicating notable Candida albicans growth. Conversely, there was no significant difference in colony diameter on SDA media. The biomass average of Candida albicans on RBC media was 0.82 g, compared to 0.45 g on SDB media. The Mann-Whitney test (p < 0.05) indicated a significant contrast in the average dry weight of Candida albicans biomass, with RBC media being heavier than SDB media. The conclusion is RBA and RBC media have the ability to grow Candida albicans which can be used as an alternative to SDA and SDB media.

Serendipita officinale sp. nov. (Serendipitaceae): a new species of orchid mycorrhizal fungus

Serendipita is a prominent fungal genus associated with orchids. In this study, a new species of orchid mycorrhizal fungus, Serendipita officinale, is described and thoroughly studied using morphological and molecular approaches. The fungus was isolated from naturally occurring protocorms of Dendrobium officinale in Chongqing Province, China. S. officinale has been observed to actively promote the germination of seeds and facilitate the seedling development of D. officinale, forming typical mycorrhizal pelotons within protocorm cells. This species is characterized by its characteristics on PDA medium, including the presence of abundant villiform and felty aerial mycelium, uninucleate hyphal cells, and the highest growth rate in terms of colony diameter (78 mm diam. in 2 weeks). Furthermore, analyses of ITS rDNA and LSU sequences also provide additional support for the novelty of this new plant symbiont.

Mannitol improves Monascus pigment biosynthesis with rice bran as a substrate in Monascus purpureus.

To reduce the production cost of Monascus pigments (MPs), the utilization of rice bran (RB), an agricultural waste product, as a substrate in submerged fermentation was conducted in this study. To improve MP production, different nutritional ingredients including mannitol (Man), NH4NO3 (AN), ZnSO4 (Zn), and optimization (Opti), which was a synthesis of the three above ones, were added in rice bran (RB) medium. The yields of MPs, pigment constituents, and growth and development of Monascus purpureus M9 were investigated in this study. Man had the maximum color value of 3,532 U/g, which was 18.69 times more than that of RB and reached up to 76.65% of the value of rice (Rice) fermentation. Man significantly increased the production of two orange pigments, monascorubrin and rubropunctatin, of which the yields were 69.49 and 95.36% of the counterpart of Rice. The biomass and colony diameter of Opti presented the maximum value among different groups. AN and RB induced more asexual spore formation, whereas Opti and Man promoted sexual spore production. Comparative transcriptomic analysis showed that different nutritional ingredients led to changes in pigment production, promoting the growth and development of M. purpureus M9 through the regulation of related gene expression. Man and Opti improved MP production by regulating the primary metabolism, including the Embden-Meyerhof pathway (EMP), the pentose phosphate (PP) pathway, the tricarboxylic (TCA) cycle, fatty acid degradation (FAD), fatty acid biosynthesis (FAB), amino acid metabolism (AAM), and fructose and mannose metabolism (FMM), to provide the precursors (acetyl-CoA and malonyl-CoA) for MP biosynthesis. This study presents a low-cost method for increasing MP production and explains the molecular mechanisms of different nutritional ingredients for enhancing MP biosynthesis.

Postharvest caffeic acid dipping enhances disease resistance and storage capacity of ‘Zaosu’ pear fruit via regulating phenylpropane metabolism

Caffeic acid, a naturally occurring and safe phenolic compound, acts as a precursor in lignin synthesis within the phenylpropane metabolism pathway. The aims of this study was to evaluate the impacts of postharvest caffeic acid immersion on Alternaria rot and postharvest quality of ‘Zaosu’ pear fruit, as well as elucidate the underlying mechanisms involved. Results showed that postharvest caffeic acid dipping effectively inhibited spore germination and colony diameter of Alternaria alternata, as well as lesion diameter in A. alternata-inoculated pears. Caffeic acid treatment also delayed the increase of weight loss and decline in flesh firmness, increased total soluble solids content, and reduced surface yellowing of pears. Additionally, caffeic acid treatment enhanced the enzymatic activities and gene transcription levels of phenylalanine ammonialyase, 4-coumarate/coenzyme A ligase, cinnamate 4-hydroxylase, peroxidase, cinnamyl alcohol dehydrogenase, and polyphenol oxidase in pears. Meanwhile, the transcription levels of p-coumarate-3-hydroxylase, caffeic acid O-methyltransferase, cinnamoyl CoA reductase, caffeoyl shikimate esterase, hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase, caffeoyl CoA O-methyltransferase, ferulic acid 5-hydroxylase, and laccase genes were also up-regulated by caffeic acid treatment in pears. Furthermore, caffeic acid dipping enhanced phenylalanine, flavonoids, caffeic acid, total phenolic compounds, and lignin levels in the fruit. Therefore, caffeic acid exhibits promising potential for enhancing resistance against A. alternata and maintaining the storage capacity of pears via inducing phenylpropane metabolism.

Physiological mechanism beneath the inhibition of Cleome spinosa against the morphology and reproduction of Fusarium oxysporum

Fusarium oxysporum is a soil-borne plant pathogen that can cause various plant diseases including cucumber wilt. An experiment was conducted to explore the physiological mechanism underlying the inhibitory activity of Cleome spinosa against the morphology and reproduction of F. oxysporum. Different concentrations of C. spinosa extracts.−0 (Z0), 5 (Z5), 15 (Z15), 30 (Z30), 45 (Z45), and 60 (Z60) mg·mL−1 were applied to F. oxysporum. Cleome spinosa extract significantly reduced the colony diameter (89.7 %) and dry mass (78.9 %) of F. oxysporum under the Z45 treatment. Moreover, spore formation was also significantly inhibited by C. spinosa extract. The spore number and germination rate decreased by 73.5 % and 83.0 %, respectively, under the Z45 treatment. The number of mycelia in the unit field of view was significantly reduced, and the mycelia were wizened with rough surfaces and more bends under the Z45 treatment. Hence, C. spinosa extracts severely damaged the morphology of F. oxysporum mycelia. Additionally, F. oxysporum could not adjust to the osmotic changes caused by C. spinosa extract, leading to membrane injury and electrolyte leakage. Finally, they impaired the antioxidant system in F. oxysporum, resulting in cell membrane injury.

Ecotoxic effect of agriculture and environmental important bioinoculant effective microorganism (EM) derived metabolites on microbial agro active agents

AbstractEffective microorganism (EM) – a mixture of beneficial microbial formulation are extensively utilized worldwide in agriculture as plant growth promotor and biocontrol agent. Because of their wide spectrum usage, it is necessary to study the non‐target effect against the beneficial organisms used in crop production. Though, the wider applications of EM in agriculture and the environment have revealed, the environmental quality management of EM mainly metabolites‐ biochemical compounds derived from EM have yet to be studied. With this objective, the present study is undertaken to evaluate the compatibility of EM derived metabolites on the selected microbial biofertilizers, biocontrol agents including biopesticidal agents. Metabolites were extracted from the culture‐free broth of EM culture using various solvents and the extracted metabolites were characterized by the gas chromatography‐ mass spectroscopy (GC‐MS). The food poisoning technique was adapted for the screening of toxic effects. Toxic effect of the metabolites derived from the respective solvent was confirmed by measuring the growth of the respective microbial strain's vegetative growth and sporulation efficacy by dual plate assay, dual liquid assay, and spore germination microscopic slide assay. Active principles of the metabolites were readily extracted in all the solvents and the possible presence of bioactive metabolites were characterized by GC‐MS. There was no significant difference between the control and extract recorded. In the case of Rhizobium leguminosarum, the colony diameters of ethyl acetate and acetone extract were 1.6 and 1.8 cm, respectively, as in control (1.8 cm). Similar findings were also recorded for Azospirillum lipoferum, Phosphobacterium sp., and Pseudomonas flurescens. However, growth inhibition including spore germination was recorded in petroleum ether and acetone extract. Further study will be useful to exploit the principles of EM and EM derived metabolites in agriculture and environment without affecting non target beneficial organism.

First Report of Alternaria Leaf Blight Caused by Alternaria alternata on Agrimonia pilosa in China.

Agrimonia pilosa is widely distributed in East Asian countries, including China, Japan, Korea and Mongolia. It is a common medicinal plant with pharmacological effects such as procoagulant, antioxidant, anti-inflammatory. In September 2022, leaf blight was the first time observed on A. pilosa in a 2.6-ha A. pilosa plantation in Harbin, Heilongjiang Province, China. The incidence of the disease reached 80%, and almost every leaf had symptoms. Initially, yellow-to-brown spots appeared on the tips or edges of the leaves. As the disease progressed, the lesions gradually enlarged and merged. Finally, the whole leaf withered. To identify the causal agent, twenty symptomatic leaves were arbitrarily collected from ten diseased plants. Diseased leaf pieces that measured 5 mm2 were disinfested in 75% ethyl alcohol for 30 s and 7% NaOCl for 60 s, rinsed three times in sterile distilled water (Sun et al. 2022), and placed on potato dextrose agar (PDA). Ten fungal isolates obtained by single-spore isolations were selected for further study. Colonies of these isolates on PDA were off-white to black with abundant cotton-like aerial hyphae, and the colony diameter was 75 to 90 mm. The isolates produced conidia that were ovate to nearly oval, gray-to-black, with 1 to 4 transverse septa and 0 to 2 oblique septa, smooth surfaced, parietal cells extending into the beak, and measured 15.0 to 35.5 × 6.0 to 13.0 μm. Conidiophores were taupe, erect or curved, branched, with pronounced spore marks. All ten fungal isolates were morphologically similar to Alternaria alternata (Simmons 2007). Two representative isolates LYC and LYC01 were used for molecular identification. The internal transcribed spacer (ITS) region, RNA polymerase second largest subunit (RPB2), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), translation elongation factor 1-alpha (TEF1), and Alternaria major allergen (Alt a 1) were amplified with the primers ITS4/ITS5(White et al. 1990), RPB2-5F2/RPB2-7CR (Khodaei and Arzanlou 2013), gpd1/gpd2, EF1-728F/EF1-986R (Sun et al. 2023) and Alt-for/Alt-rev (Woudenberg et al. 2015). The resulting sequences were deposited in GenBank (ITS, OM319510, OQ788347; RPB2, OM296263, OQ862336; GAPDH, OM296236, OQ862337; TEF1, OM238113, OQ862338; Alta1, OM171260, OQ862339). Phylogenetic analyses showed 100% identity between LYC and LYC01 and the type strain CBS 121456. Thus, the fungus was identified as A. alternata based on morphology and molecular analysis. Pathogenicity tests were done by spraying conidial suspensions containing 106 conidia/ml of A. alternata isolates LYC and LYC01 on leaves of six healthy A. pilosa plants, separately. Another six plants were sprayed with sterile distilled water as control. Both groups of plants were covered with plastic bags and placed in a greenhouse maintained at 25⁰ C. Plastic bags were removed from plants after 48 h. Fifteen days later, the disease symptoms on the inoculated plants were similar to those observed in the original sample, whereas the control plants remained healthy. The pathogenicity tests were conducted three times. The strains of A. alternata were reisolated from the symptomatic inoculated plants, confirming Koch's postulates. To our knowledge, this is the first report of A. alternata causing leaf blight on A. pilosa in China. Identifying the agent responsible for the disease can help with disease control and plant management in the field.

Study of the biofilm mechanism of C4-HSL and C6-HSL in the degradation of quinoline.

Quinoline is a hard-to-degrade organic compound widely found in coal chemical wastewater, that seriously affects the ecological environment and human health. A number of biochemical methods are already available for quinoline degradation, but the use of microbial community sensing for quinoline degradation has not been studied in depth. Therefore, this paper focuses on the enhanced mechanism of quorum-sensing signaling molecules in the biofilm formation process during quinoline degradation by functional strains of bacteria. In this paper, the effects of the signal molecules C4-HSL and C6-HSL on the adhesion ability, colony diameter, biofilm formation ability and biofilm morphology of functional strains of quinoline degrading bacteria (Ochrobactrum sp., LC-1) were investigated, and the results showed that both signal molecules promoted the biofilm formation process during the degradation of quinoline by exhibiting an efficient biofortification effect. Both signal molecules could enhance the colony diameter of strain LC-1, where C4-HSL could enhance the biomass of strain LC-1 and stimulate the secretion of extracellular polysaccharides; and C6-HSL could induce the enhancement of adhesion performance and the secretion of extracellular proteins from strain LC-1; both molecules together enhanced the biofilm formation process of strain LC-1. This study has practical application in the degradation of quinoline in coal chemical wastewater.