Potential Microbial Agents Research Articles

Design and Synthesis of 1-(2-amino-1-(4-methoxyphenyl)ethyl) cyclohexanol Analogs as Potential Microbial Agents

1-(2-amino-1-(4-methoxyphenyl)ethyl)cyclohexanol (1), on condensation with chloroacetyl chloride yielded 2-chloro-N-(2-(1-hydroxycyclohexyl)-2-(4-methoxyphenyl)ethyl)acetamide (2), which on amination with hydrazine hydrate yielded in turn 2-hydrazinyl-N-(2-(1-hydroxycyclohexyl)-2-(4-methoxyphenyl)ethyl)acetamide (3). Compound 3, on condensation with various aromatic aldehydes afforded a series of 2-(2-benzylidenehydrazinyl)-N-(2-(1-hydroxycyclohexyl)-2-(4-methoxyphenyl)ethyl)acetamides 4a-n, which upon dehydrative annulation in the presence of chloroacetyl chloride and triethylamine yielded 2-(3-chloro-2-oxo-4-phenylazetidin-1-ylamino)-N-(2-(1-hydroxycyclohexyl)-2-(4-methoxyphenyl)ethyl) acetamides 5a-n. The synthesized compounds 4a-g and 5a-g were screened for their antibacterial activity against four microorganisms: Staphylococcus aureus (Gram positive), Bacillus subtilis (Gram positive), Pseudomonas aeruginosa (Gram negative) and Escherichia coli (Gram negative). They were found to exhibit good to moderate antibacterial activity. The antifungal activities of these compounds were also tested against three different fungal species. None of them were active against the species tested.

Discovery of New Imidazolinones Derivatives as Potential Microbial Agents

A series of imidazolinone were prepared by heating the hippuric acid in presence of acetic anhydride and sodium acetate with different aromatic aldehydes gave 5-oxazolone derivatives which reacting with N-amino-2,3,4,5,6-pentafluoro benzamide in pyridine gave imidazolinone. All the synthesized compounds have been characterized on the basis of elemental analysis, IR, 1H-NMR and 13C-NMR spectral data. All the synthesized compounds have been screened against four different bacterial strains S. aureus, S. paratyphi-A, E. coli and B. subtilis and fungal strain F. molaniforme and A. niger. Some of the compound was endowed with a remarkable antibacterial as well as antifungal activity.

Design and Synthesis of 2-(5-ethyl-pyridine-2-yl) ethanol Analogs as Potential Microbial Agents

A novel series of chalcones and pyrimidines is described. The structures of the synthesized compounds were assigned on the basis of elemental analysis, IR, 1H NMR and 13C NMR spectral data. All the products were screened against different strains of bacteria and fungi. Most of these compounds showed better inhibitory activity in comparison to the standard drugs.

Combination of atmospheric and room temperature plasma and ribosome engineering techniques to enhance the antifungal activity of Bacillus megaterium L2 against Sclerotium rolfsii.

Sclerotium rolfsii is an extremely destructive phytopathogenic fungus that causes significant economic losses. Biocontrol strategies utilizing antagonistic microorganisms present a promising alternative for controlling plant pathogens. Bacillus megaterium L2 has been identified as a potential microbial biocontrol agent in our previous study; however, its efficacy in controlling pathogens has yet to meet current demands. This study aims to enhance the antifungal activity of strain L2 against S. rolfsii R-67 through a two-round mutagenesis strategy and to preliminarily investigate the mutagenesis mechanism of the high antifungal activity mutant. We obtained mutant Dr-77 with the strongest antifungal activity against R-67, and its cell-free supernatant significantly reduced the infection potential of R-67 to Amorphophallus konjac corms, which may be attributed to the antimicrobial compound phenylacetic acid (PAA), and PAA content in Dr-77 (5.78 mg/mL) was 28.90 times higher than original strain L2. This compound exhibited strong antifungal ability against R-67, with a half maximal effective concentration (EC50) value of 0.475 mg/mL, significantly inhibiting mycelial growth and destroying the ultrastructure of R-67 at EC50 value. Notably, PAA also exhibited broad-spectrum antifungal activity against six phytopathogens at EC50 value. Moreover, genome analysis revealed nine different gene mutations, including those involved in PAA biosynthesis, and the activities of prephenate dehydratase (PheA) and phenylacetaldehyde dehydrogenase (ALDH) in PAA biosynthesis pathway were significantly increased. These results suggest that the elevated PAA content is a primary factor contributing to the enhanced antifungal activity of Dr-77, and that this mutagenesis strategy offers valuable guidance for the breeding of functional microbial resources. © 2024 Society of Chemical Industry.

Evaluation of suitability and biodegradability of the organophosphate insecticides to mitigate insecticide pollution in onion farming

Organophosphates constitute a major class of pesticides widely employed in agriculture to manage insect pests. Their toxicity is attributed to their ability to inhibit the functioning of acetylcholinesterase (AChE), an essential enzyme for normal nerve transmission. Organophosphates, especially chlorpyrifos, have been a key component of the integrated pest management (IPM) in onions, effectively controlling onion maggot Delia antiqua, a severe pest of onions. However, the growing concerns over the use of this insecticide on human health and the environment compelled the need for an alternative organophosphate and a potential microbial agent for bioremediation to mitigate organophosphate pesticide pollution. In the present study, chloropyrifos along with five other organophosphate insecticides, phosmet, primiphos-methyl, isofenphos, iodofenphos and tribuphos, were screened against the target protein AChE of D. antiqua using molecular modeling and docking techniques. The results revealed that iodofenphos showed the best interaction, while tribuphos had the lowest interaction with the AChE based on comparative binding energy values. Further, protein-protein interaction analysis conducted using the STRING database and Cytoscap software revealed that AChE is linked with a network of 10 different proteins, suggesting that the function of AChE is disrupted through interaction with insecticides, potentially leading to disruption within the network of associated proteins. Additionally, an in silico study was conducted to predict the binding efficiency of two organophosphate degrading enzymes, organophosphohydrolase (OpdA) from Agrobacterium radiobacter and Trichoderma harzianum paraoxonase 1 like (ThPON1-like) protein from Trichoderma harzianum, with the selected insecticides. The analysis revealed their potential to degrade the pesticides, offering a promising alternative before going for cumbersome onsite remediation.

In vitro and in silico Studies: Penicillin-Binding Protein 2a (PBP2a) Inhibition by Stigmasterol in Banyan Hanging Roots (Ficus benjamina L.) as Novel Treatment of Methicillin-Resistant Staphylococcus aureus (MRSA)

The most common cause of nosocomial infection worldwide is caused by Gram-positive coccus bacteria or what we commonly call Methicillin-resistant Staphylococcus aureus (MRSA). This study aimed to find novel antimicrobial agents from the banyan tree (Ficus benjamina L.) hanging roots to treat MRSA. Docking experiment and well diffusion were used as in silico and in vitro experiments respectively to identify the potential of stigmasterol against MRSA. The data were analyzed statistically with one-way variance analysis (ANOVA), post-doc Tukey assay, correlation, and regression by SPSS Amos 24. In the in silico experiment, stigmasterol was strongly associated with penicillin-binding protein 2a (PBP2a) on the active side of LYS289. Thus, it had the potential to inhibit PBP2a. Disruption of cell walls, the release of cytoplasmic contents, and a decrease in the cellular volume of MRSA were caused by the inhibition of PBP2a. The well diffusion test results showed the inhibition zone in 50 - 100 μg/ml of stigmasterol against MRSA. The inhibition zone was in the range of 7.38 – 10.17 mm. The inhibition diameter indicated a significant difference with a p-value < 0.05. The results of statistical analyses indicate that stigmasterol is effective as an antimicrobial against MRSA. Stigmasterol has potential as a potential microbial agent for the therapy of MRSA.

Revealing the functional potential of microbial community of activated sludge for treating tuna processing wastewater through metagenomic analysis.

Reports regarding the composition and functions of microorganisms in activated sludge from wastewater treatment plants for treating tuna processing wastewater remains scarce, with prevailing studies focusing on municipal and industrial wastewater. This study delves into the efficiency and biological dynamics of activated sludge from tuna processing wastewater, particularly under conditions of high lipid content, for pollutant removal. Through metagenomic analysis, we dissected the structure of microbial community, and its relevant biological functions as well as pathways of nitrogen and lipid metabolism in activated sludge. The findings revealed the presence of 19 phyla, 1,880 genera, and 7,974 species, with Proteobacteria emerging as the predominant phylum. The study assessed the relative abundance of the core microorganisms involved in nitrogen removal, including Thauera sp. MZ1T and Alicycliphilus denitrificans K601, among others. Moreover, the results also suggested that a diverse array of fatty acid-degrading microbes, such as Thauera aminoaromatica and Cupriavidus necator H16, could thrive under lipid-rich conditions. This research can provide some referable information for insights into optimizing the operations of wastewater treatment and identify some potential microbial agents for nitrogen and fatty acid degradation.

Development of potential microbial agents with two new entomopathogenic fungal strains to control the red palm weevil Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae)

BackgroundEntomopathogenic fungi, representing a class of microbial agent, have been widely used in the field of pest management. The objective of this work was to isolate different species of fungi and to evaluate their virulence against the destructive and invasive red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae).ResultsTwo new entomopathogenic fungal strains isolated from dead diseased RPWs were identified as Metarhizium anisopliae ZZ-A1 and Fusarium oxysporum ZZ-L1 using growth characteristics, morphology, and rDNA-ITS sequence amplification. Bioassays showed that M. anisopliae ZZ-A1 strain exhibited significantly higher corrected mortality than F. oxysporum ZZ-L1 strain (90.92 vs. 77.28%) in fourth instar RPW larvae 12 days after treatment with a concentration of 1.0 × 1010 conidia/ml, as well as low median lethal concentration (LC50) and median lethal time (LT50) values.ConclusionsThe results suggest that both fungal isolates can potentially be developed as effective and persistent a microbial agent against this widespread pest, RPW. However, M. anisopliae ZZ-A1 showed relatively higher insecticidal activity than F. oxysporum ZZ-L1.

Brain abscess incidence and microbial etiology in Turkey: a nationwide cross-sectional study.

Brain abscess, a localized purulent central nervous system infection, arises from a variety of microorganisms. Expedited diagnosis and formulation of effective treatment strategies are crucial for mitigating mortality risks in patients with brain abscesses. A nuanced understanding of potential microbial agents is pivotal for the development of empirical antibiotic therapies. This study aimed to explore the incidence and microbial etiology of brain abscesses. This study is a nationwide cross-sectional analysis of patients diagnosed with brain abscesses in Turkey, employing the ICD 10 diagnosis code from January 1, 2015, to December 31, 2021. Data pertaining to age, sex, comorbidities, and microorganisms isolated from central nervous system samples were meticulously recorded and analyzed. This study included 11,536 patients diagnosed with brain abscesses. The incidence fluctuated between 0.98 and 3.68 during the review decrease post-2017, with a notable increase in male patients during time. Diabetes constituted 56.5% of the patients. The predominant isolated pathogens were Staphylococcus (37.6%), Streptococci (13.3%), and Klebsiella spp. (7.8%), Escherichia coli (6.4%), and Candida species (6.1%). The incidence of brain abscesses is decreasing in Turkey. Although staphylococci remain the most isolated agents, the frequent occurrence of Gram-negative bacteria and Candida species warrants consideration during empirical antibiotic selection.

Microbial degradation of the benzimidazole fungicide carbendazim by Bacillus velezensis HY-3479.

Carbendazim (methyl benzimidazol-2-ylcarbamate: MBC) is a fungicide of the benzimidazole group that is widely used in the cultivation of pepper, ginseng, and many other crops. To remove the remnant carbendazim, many rhizobacteria are used as biodegradation agents. A bacterial strain of soil-isolated Bacillus velezensis HY-3479 was found to be capable of degrading MBC in M9 minimal medium supplemented with 250mg/L carbendazim. The strain had a significantly higher degradation efficiency compared to the control strain Bacillus subtilis KACC 15590 in high-performance liquid chromatography (HPLC) analysis, and HY-3479 had the best degradation efficiency of 76.99% at 48h. In gene expression analysis, upregulation of carbendazim-degrading genes (mheI, hdx) was observed in the strain. HY-3479 was able to use MBC as the sole source of carbon and nitrogen, but the addition of 12.5mM NH4NO3 significantly increased the degradation efficiency. HPLC analysis showed that the degradation efficiency increased to 87.19% when NH4NO3 was added. Relative gene expression of mheI and hdx also increased for samples with NH4NO3 supplementation. The enzyme activity of the carbendazim-degrading enzyme and the 2-aminobenzimidazole-degrading enzyme was found to be highly present in the HY-3479 strain. It is the first reported B. velezensis strain to biodegrade carbendazim (MBC). The biodegradation activity of strain HY-3479 may be developed as a useful means for bioremediation and used as a potential microbial agent in sustainable agriculture.

Actinobacteria: an underestimated source of potential microbial biocontrol agents against fusarium-related diseases in cultivated crops

Actinobacteria: an underestimated source of potential microbial biocontrol agents against fusarium-related diseases in cultivated crops

Biological control of Fusarium-wilt and quality improvement of Sesamum indicum cv. ST-1 using fluorescent Pseudomonas

Seven plant growth-promoting bacterial strains (LES1-LES7) were isolated from rhizosphere of Lycoperscion esculentum Mill. (Tomato) and further screened based on colony morphology, carbon source utilization and biochemically characterized as fluorescent Pseudomonads. Among the isolates prominent strain identified as Pseudomonas aeruginosa LES4 produced maximum siderophores in vitro besides indole acetic acid, hydrocyanic acid, solubilized insoluble inorganic phosphate and secreted β-1, 3-glucanase urease and chitin solubilizing enzymes chitinase. It also exhibited a strong antagonism against Fusarium oxysporum f.sp. sesami when co-cultured on nutrient agar medium and inhibiting the growth of the pathogen by 69% after 5 days incubation at 28 ± 1°C. Sesame (Sesamum indicum L. cv. ST-1). When surface sterilized seeds bacterized with P. aeruginosa LES4 showed enhancement in seedling sprouting early vegetative growth, and increased seed yield components viz. biomass accumulation, and all other yield and quality improving components. Strain LES4 significantly reduced the wilt disease of sesame in F. oxysporum f.sp. sesami-infested soil. Moreover, Tn5 induced streptomycin resistant trans-conjugants of spontaneous tetracycline-resistant LES4 (designated LES4tetra+strep+) used to exhibit efficient rhizosphere colonization of sesame. Such properties of fluorescent P. aeruginosa LES4 prove it as a beneficial and potential microbial agent against wilt causing sesame.

Exploring Bacterial and Fungal Biodiversity in Eight Mediterranean Olive Orchards (Olea europaea L.) in Tunisia.

A wide array of bacteria and fungi are known for their association with pests that impact the health of the olive tree. The latter presents the most economically important cultivation in Tunisia. The microbial diversity associated with olive orchards in Tunisia remains unknown and undetermined. This study investigated microbial diversity to elucidate the microbial interactions that lead to olive disease, and the bio-prospects for potential microbial biocontrol agents associated with insect pests of economic relevance for olive cultivation in the Mediterranean area. Bacterial and fungal isolation was made from soil and olive tree pests. A total of 215 bacterial and fungal strains were randomly isolated from eight different biotopes situated in Sfax (Tunisia), with different management practices. 16S rRNA and ITS gene sequencing were used to identify the microbial community. The majority of the isolated bacteria, Staphylococcus, Bacillus, Alcaligenes, and Providencia, are typical of the olive ecosystem and the most common fungi are Penicillium, Aspergillus, and Cladosporium. The different olive orchards depicted distinct communities, and exhibited dissimilar amounts of bacteria and fungi with distinct ecological functions that could be considered as promising resources in biological control.

Nanopore-based metagenomic sequencing for the rapid and precise detection of pathogens among immunocompromised cancer patients with suspected infections.

Cancer patients are at high risk of infections and infection-related mortality; thereby, prompt diagnosis and precise anti-infectives treatment are critical. This study aimed to evaluate the performance of nanopore amplicon sequencing in identifying microbial agents among immunocompromised cancer patients with suspected infections. This prospective study enlisted 56 immunocompromised cancer patients with suspected infections. Their body fluid samples such as sputum and blood were collected, and potential microbial agents were detected in parallel by nanopore amplicon sequencing and the conventional culture method. Among the 56 body fluid samples, 47 (83.9%) samples were identified to have at least one pathogen by nanopore amplicon sequencing, but only 25 (44.6%) samples exhibited a positive finding by culture. Among 31 culture-negative samples, nanopore amplicon sequencing successfully detected pathogens in 22 samples (71.0%). Nanopore amplicon sequencing showed a higher sensitivity in pathogen detection than that of the conventional culture method (83.9% vs. 44.6%, P<0.001), and this advantage both existed in blood samples (38.5% vs. 0%, P=0.039) and non-blood samples (97.7% vs. 58.1%, P<0.001). Compared with the culture method, nanopore amplicon sequencing illustrated more samples with bacterial infections (P<0.001), infections from fastidious pathogens (P=0.006), and co-infections (P<0.001). The mean turnaround time for nanopore amplicon sequencing was about 17.5 hours, which was shorter than that of the conventional culture assay. This study suggested nanopore amplicon sequencing as a rapid and precise method for detecting pathogens among immunocompromised cancer patients with suspected infections. The novel and high-sensitive method will improve the outcomes of immunocompromised cancer patients by facilitating the prompt diagnosis of infections and precise anti-infectives treatment.

Characterization of a novel glyphosate-degrading bacterial species, Chryseobacterium sp. Y16C, and evaluation of its effects on microbial communities in glyphosate-contaminated soil

Widespread use of the herbicide glyphosate in agriculture has resulted in serious environmental problems. Thus, environment-friendly technological solutions are urgently needed for the removal of residual glyphosate from soil. Here, we successfully isolated a novel bacterial strain, Chryseobacterium sp. Y16C, which efficiently degrades glyphosate and its main metabolite aminomethylphosphonic acid (AMPA). Strain Y16C was found to completely degrade glyphosate at 400 mg·L-1 concentration within four days. Kinetics analysis indicated that glyphosate biodegradation was concentration-dependent, with a maximum specific degradation rate, half-saturation constant, and inhibition constant of 0.91459 d-1, 15.79796 mg·L-1, and 290.28133 mg·L-1, respectively. AMPA was identified as the major degradation product of glyphosate degradation, suggesting that glyphosate was first degraded via cleavage of its C–N bond prior to subsequent metabolic degradation. Strain Y16C was also found to tolerate and degrade AMPA at concentrations up to 800 mg·L-1. Moreover, strain Y16C accelerated glyphosate degradation in soil indirectly by inducing a slight alteration in the diversity and composition of soil microbial community. Taken together, our results suggest that strain Y16C may be a potential microbial agent for bioremediation of glyphosate-contaminated soil.

Soil-borne and compost-borne Penicillium sp. and Gliocladium spp. as potential microbial biocontrol agents for the suppression of anthracnose-induced decay on tomato fruits

BackgroundAnthracnose is a soil-borne tomato (Solanum lycopersicum L.) disease caused by Colletotrichum coccodes and associated with early dying syndrome and postharvest fruits decays leading to significant yield losses. A biocontrol trial was conducted using Penicillium sp. and Gliocladium spp. isolates recovered from soil and compost for the evaluation of their antifungal potential against the target pathogen.ResultsCell-free culture filtrates of the microbial agents tested at different concentrations displayed an important antifungal activity based on pathogen mycelial growth inhibition and spore germination suppression. The highest antifungal potential was induced by Penicillium sp. CH6, G. catenulatum Gc1 and G. virens Gv1 cell-free filtrates applied at 3 concentrations (10, 15 and 20% v/v). C. coccodes mycelial growth was significantly reduced by 16 to 84% with chloroform and ethyl acetate extracts of Penicillium sp. CH6 and G. catenulatum Gc1 isolates applied at the concentrations 1, 2.5 and 5% v/v. These treatments had induced an important morphological alteration to pathogen mycelium expressed mainly by a decrease in colony melanization. Testing on pathogen-inoculated fruits, treatment based on cell-free culture filtrates and organic extracts had significantly reduced anthracnose severity as compared to control. Rot lesion diameter was significantly decreased about 22% following treatments with Penicillium sp. CH6 and G. catenulatum Gc1 cell-free filtrates. All chloroform and ethyl acetate extracts of isolates tested had suppressed disease severity by 11 to 59% and 14 to 85%, respectively, as compared to the untreated control.ConclusionsThe results demonstrated the involvement of bioactive compounds in the cultural filtrates and organic extracts tested. These microbial agents may be explored as an alternative tool for the protection of tomato fruits from fungi-associated decays.

Winter Rye Cover Cropping Changes Squash (Cucurbita pepo) Phyllosphere Microbiota and Reduces Pseudomonas syringae Symptoms

Cover cropping is a soil conservation practice that may reduce the impacts of the economically important pathogen Pseudomonas syringae on crops, including squash (Cucurbita pepo). To date, no studies have directly quantified the effect of rye cover crops on P. syringae populations or on the bacterial community of squash leaves. In this work, we tested the hypothesis that the protective effects of cover cropping on squash may be mediated by cover cropping effects on the plant’s microbiota that, in turn, protect against P. syringae. Using combined 16S sequencing and culture-based approaches, we showed that rye cover cropping protects squash against P. syringae, by decreasing pathogen population size on squash leaves and increasing fruit health and marketability at harvest. We also found evidence of a strong effect of rye cover crops on bacterial communities of the squash phyllosphere. Those findings were more striking early in the growing season. Finally, we identified numerous phyllosphere bacteria belonging to the genera Sphingomonas, Methylobacterium, and Pseudomonas that were promoted by rye cover crops. Overall, our findings suggest that cover cropping is effective for the sustainable management of P. syringae on squash and may provide a reservoir of potential microbial biocontrol agents colonizing the phyllosphere. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Pediococcus pentosaceus IM96 Exerts Protective Effects against Enterohemorrhagic Escherichia coli O157:H7 Infection In Vivo.

Enterohemorrhagic Escherichia coli (EHEC) is a notorious and prevalent foodborne pathogen which can cause serious intestinal diseases. The antagonistic activity of probiotics against EHEC is promising, but most of the studies concerning this subject have been carried out in vitro. Specifically, the interaction between Pediococcus pentosaceus and EHEC O157:H7 in vivo has not been reported yet. In this study, we investigated the protective effect of P. pentosaceus IM96 on EHEC O157:H7-infected female mice in vivo. The results demonstrated that P. pentosaceus IM96 reduced the level of pro-inflammatory factors and increased the level of anti-inflammatory factors of EHEC O157:H7-infected mice. Furthermore, P. pentosaceus IM96 alleviated intestinal mucosal damage and increased the level of MUC-2, tight junction (TJ) proteins, and short chain fatty acids (SCFAs). The intestinal microbial community structure and the diversity and richness of the microbiota were also changed by P. pentosaceus IM96 treatment. In summary, P. pentosaceus IM96 exerted protective effects against EHEC O157:H7 via alleviating intestinal inflammation, strengthening the intestinal barrier function, and regulating intestinal microbiota, suggesting that P. pentosaceus IM96 might serve as a potential microbial agent to prevent and treat intestinal diseases caused by EHEC O157:H7 infection in the future.

Beauveria bassiana: as a potential microbial biocontrol agent for tea mosquito bug, Helopeltis theivora Waterhouse (Hemiptera: Miridae) in Dooars and Darjeeling, India

BackgroundIn the present study, the efficacy of two isolates of Beauveria bassiana namely, BKN20 and BKN1/14 was evaluated against the tea mosquito bug (TMB), Helopeltis theivora, Waterhouse (Hemiptera: Miridae) damaging harvestable shoots of tea plants in the Dooars and Darjeeling regions of West Bengal, India.ResultsLaboratory study revealed that, in both isolates, BKN20 was more pathogenic than BKN1/14, exhibiting 76% mortality of the test insect. The BKN20 isolate was formulated as an aqueous suspension (5%AS), and evaluated against TMB through micro-plot trials in tea plantations. The Micro-plot field study revealed a maximum of 72.19% reduction in the shoot damage due to TMB in plots sprayed with a 1000 ml/ha concentration of BKN20 5%AS containing 2 × 107 conidia/ml, as compared to the synthetic insecticide (Thiamethoxam 25%WG), where a 63.12% reduction in the shoots was recorded. Furthermore, different concentrations of the formulated BKN20 5%AS were evaluated against the test insect at 2 locations of tea gardens in the Dooars and Darjeeling regions. The results from both locations revealed that 1000 and 1200 ml/ha concentrations of BKN20 5%AS (each concentration containing 2 × 107 conidia/ml) significantly (p < 0.05) reduced the TMB population and they were more effective than Thiamethoxam 25%WG (120 g/ha). However, non-significant differences in crop yields were recorded. The formulation BKN20 5%AS was found to be non-pathogenic to non-target insects, i.e. natural enemies present in the tea ecosystem. BKN20 5%AS had no phytotoxic effect on the tea leaves, with acceptable organoleptic attributes.ConclusionThe BKN20 isolate could be commercialized as an alternative microbial insecticide to reduce the load of chemical insecticides in the tea ecosystem.

Analysis of microbial populations in plastic\u2013soil systems after exposure to high poly(butylene succinate-co-adipate) load using high-resolution molecular technique

BackgroundBio-based and biodegradable plastics are considered as plastics of the future owing to their ability to decompose under various environmental conditions. However, their effects on the soil microbiome are poorly characterised. In this study, we aimed to investigate the effects of an important bio-based and biodegradable plastic, polybutylene succinate-co-adipate (PBSA), on soil microbial diversity and community composition using high-resolution molecular technique (Illumina sequencing) targeting all three microbial domains: archaea, bacteria, and fungi.ResultsAdding high load of PBSA to soil (6% (w/w)) caused a significant decline in archaeal (13%) and fungal (45%) richness and substantial changes in both bacterial (Proteobacteria, Actinobacteria, and Acidobacteria) and fungal (Eurotiomycetes, Sordariomycetes, Leotiomycetes, and Dothideomycetes) community composition compared with no PBSA addition to soil. The combined effects of PBSA and (NH4)2SO4 fertilisation on the soil microbiome were much greater than the effects of PBSA alone. We only detected opportunistic human pathogens in low abundance on PBSA and in the surrounding soil. However, some plant pathogenic fungi were detected and/or enriched on the PBSA films and in surrounding soil. Apart from plant pathogens, many potential microbial control agents and plant growth-promoting microorganisms were also detected/enriched owing to PBSA addition. Adding high load of PBSA together with (NH4)2SO4 fertilisation can either eliminate some plant pathogens or enrich specific pathogens, especially Fusarium solani, which is economically important.ConclusionsWe conclude that high load of bio-based and biodegradable PBSA plastic may negatively affect soil microbiome.