Strain G1 Research Articles

Potential and characteristics of bio-H2 production from the garden waste of ornamental plant Malus prunifolia fruit: Comparison between ethanol-type and butyrate-type fermentations

Edible fruit waste has been studied and considered to be the ideal substrates for low-cost bio-H2 production. However, the garden waste of ornamental plant fruits, which has similar components to edible fruit, is rarely studied. In this study, the potential and characteristics of fermentative bio-H2 production from the campus ornamental plant fruit of Malus prunifolia (MP) in both ethanol- and butyrate-types were investigated. Ethanoligenens harbinense B49 and Clostridium neuense G1 were employed as the inoculums for the ethanol- and butyrate-type fermentations, respectively. The results indicated that the fruit of MP is rich in fructose and sucrose, both of strains B49 and G1 could grow well with MP powder as the carbon source for fermentation. However, a higher H2 yield of 1.77 mol-H2/mol-hexose was obtained in the butyrate-type fermentation with strain G1, which was 1.4 times of that with strain B49. C. neuense G1 was more suitable for the H2 fermentation with MP as substrate, and a H2 yield of 0.55 mol-H2/mol-hexose by strain B49 was observed in the test of buffer system exchanging from ethanol-type to the butyrate-type. In summary, garden wastes such as fruits of ornamental plants should be given more attention as low-cost fermentation substrate candidates for bio-H2 production.

Enhancing the inhibitory activities of polyphenols in passion fruit peel on α-Amylase and α-Glucosidase via β-Glucosidase-producing Lactobacillus fermentation

Passion fruit peel contained various phenolic compounds with α-glucosidase and α-amylase inhibitory activities in vitro. However, the bound state and glycosylated forms hindered their active expression. In this article, β-glucosidase-producing Lactobacilli were inoculated into fermented peels for targeted metabolism. The results showed that the release of bound polyphenols and the increase of free polyphenols were significantly correlated with β-glucosidase activity. The strain G1 with high enzyme activity degraded 48.20% of the bound polyphenols after 24 h. The ability of extracts to inhibit α-glucosidase and α-amylase activities was significantly enhanced and closely related to the content of free polyphenols (r = −0.96 and −0.88, P < 0.001). Computer-assisted screening identified 38 phenolic compounds as potential dual inhibitors of α-glucosidase and α-amylase. Among them, 22 α-glucosidase inhibitors and 24 α-amylase inhibitors were identified for the first time. Various inhibitors, including phenolic acids, flavones, and flavonols, increased in content after fermentation. The total content of 14 glycosylated polyphenols decreased to 28.38% at 48 h, which was opposite to the aglycone. Molecular docking indicated that glycosylated polyphenols bind to β-glucosidase through hydrogen bonds and van der Waals forces. Different glycosylations at the C-3 position of quercetin bound at same sites to β-glucosidase. This study contributes to the theory of enhancing the functional activity of natural products through targeted fermentation transformation.

New Strain of Bacillus amyloliquefaciens G1 as a Potential Downy Mildew Biocontrol Agent for Grape

To obtain effective biocontrol strains for downy mildew of grape, 38 endophytic bacteria were isolated from fruits, seeds, and old stems of six grape varieties. Using spot inoculation mixtures of sporangial suspensions of Plasmopara viticola and biocontrol bacterial suspension, this screen yielded three strains (G1, G5, and G9) with good antagonistic effects against P. viticola. The growth inhibition rate was 100%, which was comparable to the effect of the positive control Bacillus subtilis strain CN181. The enzyme activity and the metabolites of strain G1 were examined on casein hydrolysate medium, sodium carboxymethyl cellulose agar plates, and chrome azurol sulfonate (CAS) agar plates. The antifungal protein component was identified by liquid chromatography–mass spectrometry (LC–MS). The results showed that strain G1 was more effective against Plasmopara viticola after two field trials, and the inhibition rates of strain G1 on the seventh day of the two field trials were 47.5% and 36.9%, respectively. Strain G1 was identified as Bacillus amyloliquefaciens based on morphological examination and 16S rDNA sequence analysis. It produced proteases, cellulases, and siderophores. Crude protein of the strain mainly included the putative segregation protein SpoVG, which inhibited P. viticola.

Multidimensional combinatorial screening for high-level production of erythritol in Yarrowia lipolytica

Yarrowia lipolytica was successfully engineered to synthesize erythritol from crude glycerol, a cheap by-product of biodiesel production, but the yield remained low. Here, a biosensor-guided adaptive evolution screening platform was constructed to obtain mutant strains which could efficiently utilize crude glycerol to produce erythritol. Erythrose reductase D46A (M1) was identified as a key mutant through whole-genome sequencing of the strain G12, which exhibited higher catalytic activity (1.6-fold of the wild-type). M1 was further modified to obtain a combinatorial mutant with 4.1-fold enhancement of catalytic activity. Finally, the metabolic network was reconfigured to redirect carbon fluxes toward erythritol synthesis. The erythritol titer of the engineered strain G31 reached 220.5 g/L with a productivity of 1.8 g/L/h in a 5-L bioreactor. The study provides valuable guidance for biosensor-based ultra-high-throughput screening strategies in Y. lipolytica, as well as presenting a new paradigm for the sustainable valorization of crude glycerol.

Complete characterization of NADH dehydrogenase subunit 1 gene in human hydatid cysts

يمتلك طفيلي الاكياس العدرية سلالاتين متشابهتين (G1 و G3) ونظرا للدور البارز الذي تلعبه عائلة جينات نازعات الهيدروجين في التميز بين هاتين السلالاتين، لذا هدفت الدراسة الحالية الى اجراء التوصيف الجزيئي الكامل لاحد ابرز انواع هذه العائلة وهو الجين NAD1 (من شفرة البدء الى الي شفرة التوقف) للاكياس العدرية المعزولة جراحيا من اكباد المرضى (ولمحافظتي البصرة وميسان) في مستشفى الصدر التعليمي في محافظة البصرة، العراق. عزلت الرؤيسات الاولية من الاكياس تحت ظروف معقمة واستخدمت في استخلاص الحامض النووي منقوص الاوكسجين. اذ ضخم التتابع الكامل للجين في عينات الدراسة وانجز التتابع (السكونس) لهما باستخدام بادئات متخصصه. اظهرت نتائج تحليل السكونس المتكرر Consensus sequence امتلاك كل من عينات البصرة و ميسان 1038 زوجا من القواعد وتقع شفرة البدء GTG في الموقع 87-89 وشفرة التوقف TAA في الموقع 978-980. كما اظهرت استدلالات الاحماض الامينية الى وجود 297 حامض اميني لبروتينات عينات البصرة وميسان. فضلا عن ذلك بينت تحاليل المعلومات الحياتية احتواء هذه البروتينات على الحامض الاميني Isoleucine في الموقع 188 (I188) وهو موجود فقط في سلالة الاغنام G1. وان النموذج التركيبي لبروتينات عينات البصرة وميسان اظهر تشابها كبيرا و يقع I188 في الحلزون 10 (α10). بينت الدراسة ولاول مرة على مستوى العراق التوصيف الكامل للجين NAD1 والعائد الى سلالة الاغنام G1 المسببه لمرض الاكياس العدرية البشري.

Exploration of the catabolic plasmid genes profile of crude oil degrading bacteria isolated from aged oil contaminated soils of Anambra State

This study was undertaken to explore the catabolic plasmid genes profile and molecular identification of crude oil degrading bacteria isolated from aged oil contaminated soils of Anambra State. Enrichment technique, turbidometric test, plasmid profiling and curing tests, biodegradation capability testing as well asmolecular identification method were carried out using standard procedures.A total of sixty (60) bacterial isolates were encountered in the four different soil samples. Of the total bacterial isolates, 22 strains demonstrated high crude oil degrading potentials (A600nm &gt; 0.3). The plasmid DNA was present in 8 out of the 22 bacterial strains such that bacteria strains G2, H4, and K4 had one plasmid each with molecular weight of 9416 base pairs while bacteria strains C3, D1, J3 and L2 had two plasmids each with molecular weight of 2111 base pairs. The bacterial strains C1 and J3 recorded the highest growths on the solid media after the plasmid removal. The isolates belong to various species which are Bacillus cereus C12 (100 % similarity), Pseudomonas aeruginosa KAVK01 (100% similarity), Bacillus licheniformis 126 (96 % similarity), Ochrobacteriumintermedium E85b (97% similarity), Bacillus subtillis SDDlas (100 % similarity), Bacillus subtillis LK4.5 (97 % similarity),Enterobacter cloacae GEBRI III (97 % similarity) and Bacillus cereus So24 (100 % similarity). Therefore, plasmid-borne Pseudomonas aeruginosa and Ochrobacteriumintermediumare recommended for use in bioremediation because of their resilience to the crude oil contaminant and degradation capacities.

Genome Comparisons between Botrytis fabae and the Closely Related Gray Mold Fungus Botrytis cinerea Reveal Possible Explanations for Their Contrasting Host Ranges.

While Botrytis cinerea causes gray mold on many plants, its close relative, Botrytis fabae, is host-specifically infecting predominantly faba bean plants. To explore the basis for its narrow host range, a gapless genome sequence of B. fabae strain G12 (BfabG12) was generated. The BfabG12 genome encompasses 45.0 Mb, with 16 chromosomal telomere-to-telomere contigs that show high synteny and sequence similarity to the corresponding B. cinerea B05.10 (BcB0510) chromosomes. Compared to BcB0510, it is 6% larger, due to many AT-rich regions containing remnants of transposable elements, but encodes fewer genes (11,420 vs. 11,707), due to losses of chromosomal segments with up to 20 genes. The coding capacity of BfabG12 is further reduced by nearly 400 genes that had been inactivated by mutations leading to truncations compared to their BcB0510 orthologues. Several species-specific gene clusters for secondary metabolite biosynthesis with stage-specific expression were identified. Comparison of the proteins secreted during infection revealed high similarities, including 17 phytotoxic proteins that were detected in both species. Our data indicate that evolution of the host-specific B. fabae occurred from an ancestral pathogen with wide host range similar to B. cinerea and was accompanied by losses and degeneration of genes, thereby reducing its pathogenic flexibility.

Simultaneous immobilization of multiple heavy metal(loid)s in contaminated water and alkaline soil inoculated Fe/Mn oxidizing bacterium

Two strains of Fe/Mn oxidizing bacteria tolerant to high concentrations of multiple heavy metal(loid)s and efficient decontamination for them were screened. The surface of the bio-Fe/Mn oxides produced by the oxidation of Fe(II) and Mn(II) by Pseudomonas taiwanensis (marked as P4) and Pseudomonas plecoglossicida (marked as G1) contains rich reactive oxygen functional groups, which play critical roles in the removal efficiency and immobilization of heavy metal(loid)s in co-contamination system. The isolated strains P4 and G1 can grow well in the following environments: pH 5-9, NaCl 0-4%, and temperature 20-30°C. The removal efficiencies of Fe, Pb, As, Zn, Cd, Cu, and Mn are effective after inoculation of the strains P4 and G1 in the simulated water system (the initial concentrations of heavy metal(loid) were 1 mg/L), approximately reaching 96%, 92%, 85%, 67%, 70%, 54% and 15%, respectively. The exchangeable and carbonate bound As, Cd, Pb and Cu are more inclined to convert to the Fe-Mn oxide bound fractions in P4 and G1 treated soil, thereby reducing the phytoavailability and bioaccessible of heavy metal(loid)s. This research provides alternatives method to treat water and soil containing high concentrations of multi-heavy metal(loid)s.

Taxis-mediated bacterial transport and its implication for the cometabolism of pyrene in a model aquifer

One of the main problems in contaminated soils is that many toxic substances, such as PAHs, which are found in areas close to aquifers and groundwater, are difficult to access and degrade via traditional methods of remediation. The use of controlled bacterial mobility through chemotaxis has been shown to be efficient in increasing the dispersion of pollutant-degrading organisms, increasing the biodegradation rates of pollutants. In this study, using percolation columns as model aquifers, the mobilization of the Pseudomonas putida G7 strain to a distant pyrene source was demonstrated using γ-aminobutyric acid and artificial root exudates as strong chemoeffectors. An increase in the biodegradation rates of the pollutant was observed relative to columns in which the tactic effector was not added. The presence of different metabolites was detected via a fraction collector associated with an HPLC system, providing evidence for the cometabolic capacity of strain G7. The use of chemotactic organisms can be an effective approach for the remediation of polluted sediments associated with aquifers and groundwaters, offering new possibilities for the treatment of contaminated aqueous areas.

Fipronil Degradation in Soil by Enterobacter chengduensis Strain G2.8: Metabolic Perspective.

Fipronil is an insecticide widely used in the agricultural and veterinary sectors for its efficacy in pest control. The presence of fipronil in the environment is mainly due to agricultural and domestic practices and is frequently found in different types of environmental matrices in concentrations ranging from µg/L to mg/L and can be hazardous to non-target organisms due to its high toxicity. This study was carried out to obtain and characterize microorganisms from soil which are capable of biodegrading fipronil that could be of great biotechnological interest. For this purpose, bioprospecting was carried out using fipronil (0.6 g/L) as the main source of carbon and nitrogen for growth. Once obtained, the strain was identified by sequencing the 16S ribosomal RNA (rRNA) gene and the capacity to degrade fipronil was monitored by GC-MS. Our study showed a presence in soil samples of the strain identified as Enterobacter chengduensis, which was able to metabolize fipronil and its metabolites during the mineralization process. Enterobacter chengduensis was able to biodegrade fipronil (96%) and its metabolites fipronil-sulfone (92%) and fipronil-sulfide (79%) in 14 days. Overall, the results of this study provided a bacterium with great potential that could contribute to the degradation of fipronil in the environment.

Isolation And Characterization Of Nitrogen Fixing Fungi From Fruit And Vegetable Waste Compost

Nitrogen fixing fungi are fungi capable of fixing free nitrogen into ammonium or nitrate, so that it can be absorbed by plants. Many species of microbes/fungi have the ability to fix nitrogen, but very few are able to excrete nitrogen in the form of ammonia so that their contribution in providing nitrogen for plants is also still low. This study aims to determine the characteristics and type of nitrogen fixing fungi in fruit and vegetable waste compost. The method used in this research was descriptive method. Identification of nitrogen-fixing fungi was carried out macroscopically by looking at the color of the colonies, the shape of the colonies, and the diameter of the fungal colonies, an then identified by molecularly. There were 4 isolates of nitrogen-fixing fungi capable of forming clear zones on Jensen's media with different morphological characteristics and nitrogen-fixing abilities. The largest diameter of the clear zone was shown in isolate A3 of 3.2 cm which is the fungus Aspergillus niger strain SG1.

Trichlorobacter ammonificans, a dedicated acetate-dependent ammonifier with a novel module for dissimilatory nitrate reduction to ammonia.

Dissimilatory nitrate reduction to ammonia (DNRA) is a common biochemical process in the nitrogen cycle in natural and man-made habitats, but its significance in wastewater treatment plants is not well understood. Several ammonifying Trichlorobacter strains (former Geobacter) were previously enriched from activated sludge in nitrate-limited chemostats with acetate as electron (e) donor, demonstrating their presence in these systems. Here, we isolated and characterized the new species Trichlorobacter ammonificans strain G1 using a combination of low redox potential and copper-depleted conditions. This allowed purification of this DNRA organism from competing denitrifiers. T. ammonificans is an extremely specialized ammonifier, actively growing only with acetate as e-donor and carbon source and nitrate as e-acceptor, but H2 can be used as an additional e-donor. The genome of G1 does not encode the classical ammonifying modules NrfAH/NrfABCD. Instead, we identified a locus encoding a periplasmic nitrate reductase immediately followed by an octaheme cytochrome c that is conserved in many Geobacteraceae species. We purified this octaheme cytochrome c protein (TaNiR), which is a highly active dissimilatory ammonifying nitrite reductase loosely associated with the cytoplasmic membrane. It presumably interacts with two ferredoxin subunits (NapGH) that donate electrons from the menaquinol pool to the periplasmic nitrate reductase (NapAB) and TaNiR. Thus, the Nap-TaNiR complex represents a novel type of highly functional DNRA module. Our results indicate that DNRA catalyzed by octaheme nitrite reductases is a metabolic feature of many Geobacteraceae, representing important community members in various anaerobic systems, such as rice paddy soil and wastewater treatment facilities.

Isolation, characterization, and pathogenicity assessment of Corynebacterium pseudotuberculosis biovar equi strains from alpacas (Vicugna pacos) in China.

Corynebacterium pseudotuberculosis is a zoonotic pathogen that causes lymphadenitis in humans, livestock, and wildlife. In this study, C. pseudotuberculosis biovar equi strains were isolated from three alpacas. Antibiotic susceptibility tests and pathogenicity tests were also conducted. Moreover, one strain was sequenced using DNBSEQ and Oxford Nanopore technology. The three strains exhibited resistance to aztreonam, fosfomycin, and nitrofurantoin. The median lethal doses (LD50) of strains G1, S2 and BA3 in experimentally infected mice was 1.66 × 105 CFU, 3.78 × 105 CFU and 3.78 × 105 CFU, respectively. The sequencing of strain G1 resulted in the assembly of a chromosomal scaffold comprising 2,379,166 bp with a G + C content of 52.06%. Genome analysis of strain G1 revealed the presence of 48 virulence genes and 5 antibiotic resistance genes (ARGs). Comparative genomic analysis demonstrates a high degree of genetic similarity among C. pseudotuberculosis strains, in contrast to other Corynebacterium species, with a clear delineation between strains belonging to the two biovars (ovis and equi). The data of the present study contribute to a better understanding of the properties of C. pseudotuberculosis biovar equi strains and the potential risk they pose to alpacas and other livestock, as well as the necessity of ongoing surveillance and monitoring of infectious diseases in animals.

Investigation of variants in genetics and virulence of Porcine Epidemic Diarrhea Virus after serial passage on Vero cells

Porcine epidemic diarrhea virus (PEDV) is a highly contagious intestinal virus. However, the current PEDV vaccine, which is produced from classical strain G1, offers low protection against recently emerged strain G2. This study aims to develop a better vaccine strain by propagating the PS6 strain, a G2b subgroup originating from Vietnam, on Vero cells until the 100th passage. As the virus was propagated, its titer increased, and its harvest time decreased. Analysis of the nucleotide and amino acid variation of the PS6 strain showed that the P100PS6 had 11, 4, and 2 amino acid variations in the 0 domain, B domain, and ORF3 protein, respectively, compared to the P7PS6 strain. Notably, the ORF3 gene was truncated due to a 16-nucleotide deletion mutation, resulting in a stop codon. The PS6 strain's virulence was evaluated in 5-day-old piglets, with P7PS6 and P100PS6 chosen for comparison. The results showed that P100PS6-inoculated piglets exhibited mild clinical symptoms and histopathological lesions, with a 100% survival rate. In contrast, P7PS6-inoculated piglets showed rapid and typical clinical symptoms of PEDV infection, and the survival rate was 0%. Additionally, the antibodies (IgG and IgA) produced from inoculated piglets with P100PS6 bound to both the P7PS6 and P100PS6 antigens. This finding suggested that the P100PS6 strain was attenuated and could be used to develop a live-attenuated vaccine against highly pathogenic and prevalent G2b-PEDV strains.

Gamma-aminobutyric acid (GABA) production by potential probiotic strains of indigenous fermented foods origin and RSM based production optimization

The study aimed to evaluate the γ-aminobutyric acid (GABA) producing lactic acid bacterial strains of fermented food origin to be used as potential psychobiotic. A total of 268 isolates were screened for GABA production using the pH indicator method. Five of the isolates were identified as potential GABA producers and were shortlisted further for confirmation of GABA production by NMR and HPLC analysis. One of the strains (G2), identified as Weissella confusa showed the highest production of GABA (246.2 mg/L) while the remaining strains produced only trace amounts. These five strains were assessed for safety and probiotic properties. The strain G2 exhibited the most prominent probiotic properties. It showed good tolerance towards pH(2 and 3), bile salt(0.3–1%), gastro-intestinal fluid, NaCl(1–4%), phenol(0.4–0.6%), auto-aggregation(83%), strong hydrophobicity to xylene(70%) and chloroform(78%), significant antimicrobial activity, susceptibility to antibiotics and strong adherence to Caco-2 cells. From the optimization of culture conditions for GABA production by RSM based approach, G2 was found to produce 293.33 mg/L with a 34h fermentation time, 29.1 °C temperature, and at 1% mono-sodium glutamate concentration. Further studies are needed to assess the efficacy and stability of the isolate in the food matrix and in vivo gut environment, to utilize it as a potential psychobiotic.

Methanocaldococcus lauensis sp. nov., a novel deep-sea hydrothermal vent hyperthermophilic methanogen.

Three hyperthermophilic methanogens, designated strain SG7T, strain SG1 and strain SLH, were isolated from the ABE and Tu’i Malila deep-sea hydrothermal vent fields along the Eastern Lau Spreading Center. Phylogenetic analysis based on 16S rRNA gene sequence indicated that strains SG7T, SG1 and SLH were affiliated with the genus Methanocaldococcus within the family Methanocaldococcaceae , order Methanococcales . They shared 95.5–99.48 % 16S rRNA gene sequence similarity to other Methanocaldococcus species and were most closely related to Methanocaldococcus bathoardescens . Cells of strains SG7T, SG1 and SLH were cocci, with a diameter of 1.0–2.2 µm. The three strains grew between 45 and 93 °C (optimum, 80–85 °C), at pH 5.0–7.1 (optimum pH 6.2) and with 10–50 g l−1 NaCl (optimum 20–25 g l−1). Genome analysis revealed the presence of a 5.1 kbp plasmid in strain SG7T. Based on the results of average nucleotide identity and digital DNA–DNA hybridization analyses, we propose that strains SG1 and SG7T are representatives of a novel species, for which the name Methanocaldococcus lauensis sp. nov. is proposed; the type strain is SG7T (=DSM 109608T=JCM 39049T).

Characterization of biosurfactant-producing bacterial strains isolated from agro-industrial wastes in southwestern, Nigeria

Introduction. The difficulty of managing trash and cleaning up the environment prompted interest in biosurfactants and surface-active proteins made by microbes. The study aims to augment bacterial isolates from agro-industrial wastes targeted for possible mass production of biosurfactants. Methods. Six agro-industrial wastes from Cassava, Palm kernel, and Sawdust from six agro-industrial sites within Ijebu area in Ogun State were collected for standard laboratory analyses in the Biotechnology Unit of the Federal Industrial Institute for Research, Oshodi (FIIRO). Five screening methods; blood hemolysis, lipase activity, blue agar hydrolysis, oil spreading, and emulsification index (EI24) were carried out to confirm biosurfactant production. Isolates with the highest hyper-production were subjected to 16rRNA molecular identification. Results. The study justified efficient biosurfactant production from 4 bacterial isolates out of 26 screened bacterial isolates from hydrocarbon degraders and 29 heterotrophic screened bacterial isolates, making a total of 55 screened bacterial isolates. Screening results reveal the emulsification capacities of identified Pseudomonas putida strain SG1, Acinetobacter baumanii strain MS14413, Bacillus zhangzhouensis strain cdsV18, and Burkholderia cepacia strain 717. Conclusion. Biosurfactant bacteria produced in all agricultural and industrial wastes considered in this study are capable of mass production.

Complete Genome Sequence of Phaeobacter sp. Strain G2, Isolated from a Lab Culture of the Calcifying Alga Emiliania huxleyi.

We report the complete genome sequence of Phaeobacter sp. strain G2, which was isolated from a lab culture of the coccolithophore alga Emiliania huxleyi strain RCC 1216. The 4,963,472-bp sequence has a G+C content of 58.85% and was assembled using Illumina short reads and Oxford Nanopore Technologies long reads.

First Report of Lecanicillium aphanocladii causing rot of Morchella sextelata in China.

Morel mushroom (Morchella spp.) is a rare edible fungus with high nutritional and medicinal value. In China they are cultivated in sandy soils in greenhouses and production of fresh mushrooms reached 10,000 tons in 2019. However, from 2019 to 2020, a serious rot disease with 30% natural incidence was observed on M. sextelata at a mushroom farm in Pinghu (N30°39', E121°2'), Zhejiang province of China. The symptoms mainly occurred after the first flush in the early February. First, a small white mold-like symptoms appeared on the surface or the pinnacle of pileus. Then the lesion developed to encircle the pileus and spread gradually to the stipe. The lesions expanded rapidly at high temperature (>20 °C) and humidity (>70%). In the final stages of infection, the fruiting bodies became soft with white molds. The pathogen was isolated from the margin of the lesions by plating onto potato dextrose agar (PDA) and incubated at 25 °C in the dark. Colonies on PDA grew fast, reaching 60 mm in 7 days at 25 °C, and were white to cream in color, while the back of colonies appeared red to brick-red gradually. Conidiogenous cell was solitary or in whorls of 2-4, flask-shaped in the beginning, and tapered into a thread-like neck. Conidia were borne at the tips of conidiogenous cells, were oval to sub-globose, and ranged from 1.2-2.0 µm in width and 3.2-4.3 µm in length. All these characteristics were consistent with those of Lecanicillium aphanocladii (Zare R and Gams W. 2001). To confirm the identity of the pathogen (L. aphanocladii strain G1), the genomic fragments for the internal transcribed spacer (ITS) and RNA polymerase II second largest subunit (RPB2) gene of the isolate were amplified by PCR (White et al. 1990; Zhou et al. 2020). The resulting sequence was deposited in GenBank with accession No. OL629617 and No. ON005041, respectively. BLAST results showed >99% identity with those of L. aphanocladii (MG593981.1 and KM283853.1, respectively). Concatenated sequences of the two genes in L. aphanocladii strain G1 were used to conduct a phylogenetic analysis using Bayesian inference (BI) and maxium likelihood (ML) methods in MEGA6 (Tamura et al. 2013). The pathogen was grown in PDB medium at 25 °C, 200 r/min for 14 days, and after which conidial suspension (1×107conidia/mL) was prepared by filtration with four layers of sterile gauze. A pathogenicity test was performed by spraying on ten fruit bodies of M. sextelata and cultured in 20 °C and 90 to 95% relative humidity for 7 days. The test results showed that the pathogen infected the pileus and developed into white mold-like lesion, gradually spread to the stipe, and eventually the whole fruiting body became soft with white molds. The pathogen was re-isolated from infected fruiting bodies and was confirmed to be L. aphanocladii, based on morphological characteristics and the ITS, RPB2 sequence. Meanwhile,the control M. sextelata was sprayed with PDB medium and grew normally without any symptoms. L. aphanocladii has been reported on cultivated fungi such as Agaricus bisporus and A. bitorquis in Europe (Zare & Gams 2001) as well as more recently on Tremella fuciformis in China (Liu et al 2018). To our knowledge, this is the first report of L. aphanocladii causing rot of M. sextelata. According to the disease observation in the farm of Pinghu, this rot disease breaks out and spreads fast, and is getting worse ever year, resulting in a huge loss of yield and commodity value. It is a big concern to producers of this edible fungus.

First Study Case of Microbial Biocontrol Agents Isolated from Aquaponics Through the Mining of High-Throughput Sequencing Data to Control Pythium aphanidermatum on Lettuce.

Aquaponics is defined as a sustainable and integrated system that combines fish aquaculture and hydroponic plant production in the same recirculated water loop. A recent study using high-throughput sequencing (HTS) technologies highlighted that microbial communities from an aquaponic system could control one of the most problematic pathogens in soilless lettuce culture, namely, Pythium aphanidermatum. Therefore, this study aims at isolating the microorganisms responsible for this biocontrol action. Based on the most promising genera identified by HTS, an innovative strategy for isolating and testing original biocontrol agents from aquaponic water was designed to control P. aphanidermatum. Eighty-two bacterial strains and 18 fungal strains were isolated, identified by Sanger sequencing, and screened in vivo to control damping-off of lettuce seeds caused by P. aphanidermatum. Out of these 100 isolates, the eight most efficacious ones were selected and further tested individually to control root rot disease caused by the same pathogen at a later stage of lettuce growth. Strains SHb30 (Sphingobium xenophagum), G2 (Aspergillus flavus), and Chito13 (Mycolicibacterium fortuitum) decreased seed damping-off at a better rate than a propamocarb fungicide and a Pseudomonas chlororaphis registered biocontrol agent did. In root rot bioassays, lettuce mortality was prevented by applying strains G2 and Chito13, which were at least as efficacious as the fungicide or biopesticide controls. Lettuce disease symptoms and mortality were eradicated by strain SHb30 in the first bioassay, but not in the second one. These results show that aquaponic systems are promising sources of original biocontrol agents, and that HTS-guided strategies could represent interesting approaches to identify new biocontrol agents.