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Hypocreales
Hypocreales
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Hypocreales
Tolypocladium sp.
Scientific classification Edit this classification
Kingdom: Fungi
Division: Ascomycota
(unranked): Sordariomyceta
Class: Sordariomycetes
Subclass: Hypocreomycetidae
Order: Hypocreales
Lindau (1897)

The Hypocreales are an order of fungi within the class Sordariomycetes.

In 2008, it was estimated that it contained some 237 genera, and 2647 species in seven families.[1] Since then, a considerable number of further taxa have been identified, including an additional family, the Stachybotryaceae.[2] Wijayawardene et al. in 2020 added more families and genera to the order.[3] According to the Catalog of Life, as of April 2021 the Hypocreales contains 6 families, 137 genera, and 1411 species.[4] Hyde et al. (2020a) listed 14 families under Hypocreales, while, Wijayawardene et al. (2022) accepted 15 families in the order,[5] where Cylindriaceae was additionally added. Earlier, Hyde et al. (2020a) had placed Cylindriaceae in class Xylariomycetidae.[6] Samarakoon et al. (2022) agreed.[7] Hence, Cylindriaceae should have been excluded from Hypocreales and placed in Xylariomycetidae. Xiao et al. (2022) recently introduced a new family Polycephalomycetaceae to Hypocreales.[8]

Description

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Species of Hypocreales are usually recognized by their brightly colored, perithecial ascomata, or spore-producing structures. These are often yellow, orange or red.

Families

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(with amount of genera);[3][5]

Former families:

Genera incertae sedis

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According to a 2020 review of fungal classification, the following genera within the Hypocreales have an uncertain taxonomic placement (incertae sedis), and have not been assigned to any family:[3]

Genera formerly included:

  • Berkelella (Sacc.) Sacc. (1891) – 2 spp. now in Clavicipitaceae 2022

References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia
from Grokipedia
Hypocreales is an order of filamentous fungi within the class and phylum , encompassing over 300 genera and more than 6000 species (as of 2025), many of which exhibit in natural settings through conidia production. These fungi are characterized by diverse reproductive structures, including synnematous conidiophores and aseptate, to colored conidia, with some species producing ascospores or actively discharging spores. Ecologically, Hypocreales species play significant roles as entomopathogens that infect and other arthropods via penetration, often demonstrating high ; they also function as plant pathogens, endophytes, mycoparasites, saprophytes, and parasites of nematodes, rotifers, slime molds, and other fungi. The order includes several prominent families, such as Clavicipitaceae, Cordycipitaceae, Ophiocordycipitaceae, and Nectriaceae, which have been refined through molecular phylogenetic analyses linking teleomorphs (sexual stages, e.g., Cordyceps) to anamorphs (asexual stages, e.g., Beauveria). Notable genera encompass entomopathogenic species like Beauveria (e.g., B. bassiana, a ubiquitous soil inhabitant used in biocontrol), Metarhizium (e.g., M. anisopliae, a generalist with phenotypic plasticity), and Isaria, alongside plant-associated genera such as Hypocrea (with anamorph Trichoderma, known for mycoparasitism) and Nectria. These fungi are particularly valued in agriculture and forestry for their potential as biological control agents against insect pests, with species like Metarhizium acridum targeting locusts and Beauveria brongniartii controlling soil-dwelling beetles. Additionally, some Hypocreales, such as Escovopsis in Hypocreaceae, specialize in niche interactions, like parasitizing fungal gardens of attine ants. Hypocreales diversity is globally distributed, with high species richness in tropical and temperate regions, and ongoing taxonomic revisions—driven by genomic and phylogenetic studies—continue to reveal new genera and species, particularly in biodiverse areas like . Their metabolic versatility, including production of secondary metabolites like beauvericin and destruxins, contributes to their pathogenicity and ecological adaptability, underscoring their importance in both natural ecosystems and applied .

Taxonomy and Classification

Historical Development

The order Hypocreales was initially established by in 1897 as part of the Pyrenomycetes (then classified within the Sphaeriales), primarily based on the morphology of perithecia and characteristics of ascospores, with Hypocrea designated as the within the Hypocreaceae. This foundational classification emphasized the bright-colored, often stromatic ascomata and unitunicate asci typical of the group, distinguishing it from other pyrenomycetous fungi. In the early 20th century, mycologists such as Franz von Höhnel expanded the taxonomic scope of Hypocreales by incorporating additional genera, including Hypocrea and , through detailed examinations of stromatal structures and conidial features in anamorphic states. Höhnel's contributions, including descriptions of genera like Stylonectria in 1915, highlighted the diversity of hypocrealean fungi and their connections to insect-associated and lignicolous habits, broadening the order beyond initial perithecial-focused criteria. These expansions reflected a growing recognition of the order's morphological plasticity, setting the stage for further integrations of teleomorph-anamorph linkages. By the mid-20th century, Clark T. Rogerson's 1970 monograph provided a comprehensive reclassification, emphasizing apex structures and connections between sexual and asexual morphs, which facilitated the order's placement within the newly defined class . Rogerson's work synthesized over 50 genera, underscoring the Hypocreales' monophyletic potential based on shared unitunicate and colorful stromata, while addressing nomenclatural issues from earlier morphological studies. Phylogenetic advancements in the late 20th and early 21st centuries, particularly Stephen A. Rehner and Gary J. Samuels' analysis using nuclear large subunit (LSU) rDNA sequences from 40 species, confirmed the of Hypocreales and demonstrated its distinction from other sordariomycete orders, with Clavicipitales emerging as derived within it. This molecular framework integrated teleomorphs like Nectria and anamorphs such as , resolving longstanding ambiguities in generic boundaries. In the 2020s, multi-gene phylogenetic studies incorporating loci such as LSU, RPB2, and TEF further refined the order's , with Kevin D. Hyde et al.'s 2020 outline recognizing 14 families based on robust support and divergence estimates. Subsequent revisions, including those to Bionectriaceae in 2025, have incorporated additional genera and addressed through expanded datasets, enhancing the order's alignment with ecological and evolutionary patterns.

Current Classification

Hypocreales is currently classified as an order within the subclass Hypocreomycetidae, class , and phylum , reflecting the phylogenetic consensus derived from recent multi-locus analyses across . This placement is supported by 2025 updates in mycological literature, which affirm its position based on robust molecular phylogenies integrating ribosomal and protein-coding genes. The order is defined as a monophyletic , evidenced by high bootstrap support (>95%) in analyses using markers such as 28S rDNA (LSU), RPB1, RPB2, and TEF1-α, which delineate its boundaries within . According to Hyde et al. () and subsequent 2025 revisions, Hypocreales encompasses 14 families, approximately 303 genera, and over 2,500 species, highlighting its extensive diversity across saprotrophic, parasitic, and symbiotic lifestyles. Key diagnostic criteria for Hypocreales include powdery to slimy stromata that are often brightly colored, cylindrical asci featuring an apical pore, and to pigmented ascospores, which may be septate or possess distinctive ornamentation. These morphological traits, combined with molecular data, facilitate family-level delineations. Subordinal divisions recognize distinct clades, such as the clavicipitoid group (primarily entomopathogenic, linked to anamorphs like and ) and the hypocreoid group (often saprotrophic, associated with genera like Hypocrea and ), based on integrated anamorph-teleomorph connections and phylogenetic evidence.

Morphology and Life Cycle

predominates in many genera of Hypocreales, where anamorphic stages are more frequently observed in natural settings and cultures than the teleomorphic sexual stages, facilitating rapid propagation and identification in ecological and applied contexts. These anamorphs typically involve conidiogenesis, the production of asexual spores (conidia) via specialized hyphal structures called conidiophores, which arise from the on various substrates. Conidiophores in Hypocreales exhibit morphological diversity, ranging from mononematous forms—simple, unbranched or sparsely branched erect structures—to synnematous types, where conidiophores aggregate into coremia or synnemata. For instance, in the genus Trichoderma (anamorph of Hypocrea), conidiophores are often verticillate, featuring whorls of branches that terminate in phialides, producing conidia through holoblastic or enteroblastic mechanisms. Synnematous conidiophores occur in genera like Gliocladium, where fused hyphae form elongated, brush-like structures bearing conidia at their apices, as seen in Gliocladium-like states of some Hypocreaceae species. Conidia of Hypocreales are generally (transparent), unicellular to multicellular, and vary in shape from globose to ellipsoidal or cylindrical, often arranged in chains, dry dispersions, or slimy heads for protection and dispersal. In Hypocrea species, conidiogenesis is typically phialidic, with conidia forming at the tips of flask-shaped phialides and aggregating into slimy, greenish heads that dry to powdery masses; these conidia measure 3–5 μm long and 2–4 μm wide, with smooth walls. Multicellular conidia with 1–3 appear in some taxa, such as Cladobotryum anamorphs in Hypocreaceae, where they are ellipsoidal to and 9.5–30 μm long. Representative examples illustrate family-specific anamorphic diversity: in Bionectriaceae, many species exhibit -like states, characterized by simple mononematous conidiophores producing solitary, ellipsoidal, hyaline conidia in wet heads. In Clavicipitaceae, verticillium-like anamorphs predominate, with slender, whorled conidiophores bearing phialides that release chains of cylindrical to ellipsoidal, aseptate conidia, as in genera related to section Prostrata. Dispersal of these conidia relies primarily on abiotic agents, with wind-blown propagules enabling widespread colonization of new substrates, though some form slimy aggregates that adhere to vectors or persist in moist environments. This mechanism supports the opportunistic lifestyle of many Hypocreales fungi, linking asexual phases briefly to potential sexual cycles in compatible conditions.

Sexual Reproduction

Sexual reproduction in Hypocreales, the teleomorphic phase, involves the development of stromata that house perithecia, the fruiting bodies containing asci and ascospores. Stromata vary from immersed to superficial and are frequently brightly colored, ranging from yellow to red, formed by compacted hyphae or pseudoparenchymatous tissue. These structures, often pulvinate or cushion-shaped and measuring up to several millimeters in diameter, embed perithecia, which are ostiolate and flask-shaped with walls composed of 3–4 layers of thin-walled cells, typically 10–20 μm thick. For instance, in genera like Hypocrella and Moelleriella, stromata develop on insect hosts and exhibit variable textures from fleshy to tough. Asci in Hypocreales are unitunicate, cylindrical, and typically deliquesce upon maturation, often featuring crozier-like structures at the apex for ascus development. They possess an apical pore that is frequently , staining blue with iodine, a characteristic shared with many . Asci measure 120–325 μm in length and 5–18 μm in width, with a thickened cap (1–6 μm) and an inconspicuous ring at the tip; each contains eight ascospores arranged uniseriately. Examples include the cylindrical asci of Hypocrea species, which correlate in size with ascospore dimensions. Ascospores are and exhibit diverse morphologies, from aseptate to multi-septate, to allantoid, and may disarticulate into part-spores. In many species, they are filiform or long-, 45–140 μm long, with smooth walls; some, like those in , feature gelatinous sheaths aiding dispersal. In Hypocrea, ascospores are 1-septate, green-tinged, and break into 16 part-ascospores per , measuring 2.5–13.5 μm. Multi-septate ascospores in Moelleriella disarticulate at septa into fusoid or cylindrical part-spores (4.5–30 μm). The begins with in ascogenous hyphae, where compatible nuclei fuse to form diploid zygotes, followed by meiosis within developing asci to yield four haploid nuclei, and subsequent mitotic divisions producing eight ascospores. This occurs in binucleate cells of ascogenous hyphae derived from fertilized ascogonia, typical of . Many Hypocreales species produce teleomorphs primarily in natural conditions on specific substrates, with induction in culture challenging and often unsuccessful, though molecular data, such as multi-gene phylogenies, reliably link these teleomorphs to their anamorphic counterparts like or .

Ecology and Distribution

Habitats and Substrates

Hypocreales exhibit a , occurring across tropical, subtropical, and temperate zones worldwide. This broad range spans diverse ecosystems, from arid regions to high-latitude areas, with species reported in both terrestrial and aquatic environments. Highest diversity is observed in humid forest ecosystems, particularly in the Neotropics, where genera such as (formerly ) thrive in the understories of Amazonian rainforests in countries like and . For instance, surveys in conserved Neotropical rainforests have documented elevated of entomopathogenic Hypocreales compared to disturbed or agricultural habitats. The order primarily colonizes lignicolous (wood-decaying) and corticolous (bark-inhabiting) substrates, reflecting adaptations to decomposing plant material in forested settings. However, substrates extend to herbicolous (plant-associated) and fungicolous (fungi-inhabiting) niches, including , decaying , and other fungal hosts in terrestrial habitats. Many species are also associated with and layers on floors, where they contribute to processes. In agricultural contexts, genera like are prevalent in soils, enhancing nutrient cycling and microbial interactions in crop fields. Aquatic and marine occurrences of Hypocreales remain rare but are increasingly documented, particularly in freshwater sediments and coastal marine environments. Recent studies have identified novel species from algal substrates and sediments in the , highlighting algicolous associations in marine habitats. These findings underscore limited but expanding records of Hypocreales in submerged or sediment-bound niches, often as saprophytes. Climatically, many entomopathogenic species within Hypocreales prefer high- environments, such as the understories of tropical and subtropical forests, where relative humidity supports dispersal and . Altitudinal patterns vary, with elevated diversity noted across gradients in humid montane forests, from lowlands to mid-elevations, influenced by .

Ecological Interactions

Hypocreales fungi exhibit diverse biotic interactions, ranging from to , which position them across multiple trophic levels in ecosystems. Many species in the family Clavicipitaceae, such as and Metarhizium anisopliae, are entomopathogenic, infecting through cuticle penetration using specialized appressoria and hydrolytic enzymes that degrade the , leading to systemic mycosis and host death. These fungi produce toxins like beauvericin and destruxins, which disrupt , and sporulate on cadavers to disseminate, thereby regulating insect populations in soil and terrestrial food webs. Mycoparasitism is prominent in genera like , where species such as T. virens and T. atroviride directly attack other fungi by coiling hyphae around host hyphae and secreting lytic enzymes, including chitinases and glucanases, to lyse cell walls and absorb nutrients. This interaction often manifests as hyperparasitism, with Hypocrea (the teleomorph of ) parasitizing fungal pathogens of plants or , thereby indirectly benefiting higher trophic levels by suppressing spread. Such mycoparasitic behaviors enhance fungal diversity in microbial communities and contribute to by controlling phytopathogens. Certain Hypocreales species engage in endophytism and saprotrophy, forming symbiotic or roles. For instance, Claviceps species, including C. purpurea, act as endophytes in grasses, colonizing ovarian tissues and producing alkaloids that deter herbivores, thus providing mutualistic protection to host s while completing their life cycle. Other members, such as various Trichoderma and clavicipitaceous fungi, function as saprotrophs, breaking down lignocellulosic in decaying and through extracellular enzymes, facilitating nutrient recycling in and ecosystems. Overall, Hypocreales occupy trophic positions from primary s of to apex parasites targeting and fungi, influencing community dynamics and in terrestrial habitats.

Diversity and Systematics

Major Families

The order Hypocreales encompasses 14 recognized families as per recent classifications, representing a diverse assemblage of fungi primarily distinguished by molecular phylogenies utilizing genes such as RPB2 and TEF, alongside morphological traits like perithecial structures and conidial states. These families collectively account for over 300 genera and thousands of , with phylogenies revealing well-supported clades that have incorporated new taxa from 2025 studies, including expansions in insect-parasitic and saprobic lineages. Bionectriaceae is one of the largest families, comprising about 50 genera such as Bionectria, Gliocladium, , and Clonostachys, characterized by brightly colored stromata and acremonium-like anamorphs with phialidic conidiogenous cells producing conidia. This family encompasses approximately 350 species, many of which are saprobic on wood or , with recent phylogenetic analyses based on RPB2 and TEF confirming its and adding genera like Proliferophialis and Ramosiphorum from sediment-associated fungi. Clavicipitaceae includes approximately 55 genera and over 700 species, featuring prominent entomopathogens like , , , and Claviceps, often with synnemata or erect stromata and filiform ascospores adapted for parasitism. Diagnostic traits include clavate to elongate stromata and enteroblastic conidiogenesis, with recent studies using multi-gene phylogenies (including RPB2 and TEF) describing new genera such as Morakotia (2021) and Neoaraneomyces (2025) from hosts. Hypocreaceae is notable for wood-decaying species, including the type genus Hypocrea and its anamorph Trichoderma, which produce green-spored conidia via branched conidiophores and effuse colonies. The family contains about 20–30 genera and hundreds of species, with Trichoderma alone exceeding 500 species valued for biocontrol; phylogenies relying on RPB2 and TEF have refined its boundaries, incorporating recent isolates from decaying substrates. Nectriaceae comprises cosmopolitan plant pathogens and saprobes, with key genera like Nectria, Fusarium, and cosmopolitan species exhibiting flask-shaped perithecia and vibrant pigmentation in stromata. It includes over 50 genera and more than 1,000 species, characterized by fusiform ascospores and phialidic conidia; 2025 molecular studies using RPB2 and TEF have added taxa like Luteonectria and resolved subclades within Fusarium. Other families contribute to the order's diversity, including Calcarisporiaceae, which features lichenicolous fungi like Calcarisporium and Neobaryopsis, with expansions in the latter genus documented in 2025 based on LSU and RPB2 phylogenies, now encompassing about 14 species across 3 genera with calcarisporium-like conidia. Ophiocordycipitaceae focuses on insect parasites such as Ophiocordyceps and Hirsutella, with elongated stromata and about 25 genera including ~250 species in Ophiocordyceps, supported by TEF and RPB2 analyses revealing new lineages in 2025. The remaining families, such as Cordycipitaceae, Hausknechtomycetaceae, and Sarocladiaceae, add specialized niches like arthropod pathogens and soil saprobes, with family-level clades consistently resolved via RPB2 and TEF multi-locus phylogenies in recent updates.

Genera Incertae Sedis

As of 2025, Hypocreales encompasses approximately 20-30 genera classified as , reflecting unresolved taxonomic placements due to sparse molecular data, ambiguous phylogenetic signals, or reliance on outdated morphological traits, as cataloged in fungal databases like Faces of Fungi and recent phylogenetic studies. These genera represent a diverse array of saprobic, lichenicolous, and , often isolated from specialized substrates such as leaf litter, , or , where limited sampling hinders family-level assignment. Key examples include Trichonectria, a lichen-inhabiting genus with unstable phylogenetic positions in multi-gene analyses, resulting in its persistent status despite affinities to Bionectriaceae-like conidial morphs (Perera et al. 2023; Hyde et al. 2024). Similarly, Emericellopsis has been transferred to following phylogenetic revisions that revealed polyphyletic signals and insufficient sequence coverage for robust placement, though it shares morphological overlaps with Microascales genera (Jones et al. 2023). Chlorocillium, an entomopathogenic taxon, remains unassigned due to conflicting anamorph links resembling , with molecular data supporting Hypocreales but no clear family ties (Zhang et al. 2025). Other prominent genera in this category encompass Pseudoacremonium, Stilbella, Illosporium, and Diploospora, each exhibiting variable conidiogenous structures that defy current family delimitations (Hyde et al. 2022). The primary criteria for designation involve inadequate multilocus sequence data (e.g., fewer than three genes like ITS, LSU, and RPB2), evidence of in Bayesian or maximum likelihood trees, or dependence on obsolete keys emphasizing stromatal or ascospore morphology without genomic support (Hyde et al. 2020). Provisional affinities are often inferred for some, such as those with phialidic or annellidic conidial states aligning near Bionectriaceae, while others like lichen-associated taxa may warrant separate family elevations pending phylogenomic analyses (Perera et al. 2023). A 2025 study introduced Marquandomyces ulvae M.M. Wang & W. Li, a new algal-associated species in the existing genus Marquandomyces (Clavicipitaceae) from intertidal sediments in , exemplifying how emerging discoveries from underrepresented habitats contribute to ongoing taxonomic refinements rather than necessarily expanding the incertae sedis pool. Conservation implications are significant, as many incertae sedis genera are rare endemics known from single localities, vulnerable to habitat loss; ongoing revisions using next-generation sequencing could resolve placements and highlight hotspots for protection (Hyde et al. 2024).

Economic and Biotechnological Importance

Pathogenic Roles

Hypocreales fungi exhibit significant pathogenic roles across , , arthropods, and occasionally humans and other animals, primarily through families such as Nectriaceae and Clavicipitaceae. In , species in the Nectriaceae, particularly spp., are major pathogens causing vascular wilts, root rots, and ear rots in crops like , , and tomatoes, leading to substantial economic losses estimated at billions annually in global agriculture. These infections often involve the production of mycotoxins such as fumonisins, which disrupt plant cell membranes and inhibit , exacerbating disease severity and contaminating harvests with toxins harmful to consumers. For and arthropods, genera such as (Clavicipitaceae) and (Cordycipitaceae) act as entomopathogens, infecting pests such as locusts, beetles, and mites through penetration, which triggers epizootics that can decimate populations in agricultural and natural settings. These fungi secrete -degrading enzymes, including proteases, to breach the host , followed by dissemination that leads to host and death, thereby influencing pest dynamics and in ecosystems. In humans and animals, Hypocreales infections are typically opportunistic and rare but can be severe, with Fusarium spp. causing keratitis—a corneal infection often linked to trauma or contact lens use—and disseminated fusariosis in immunocompromised individuals, resulting in high mortality rates up to 50% in invasive cases. Claviceps purpurea, another Hypocreales member, produces ergot alkaloids that cause ergotism, a toxicoses affecting livestock and potentially humans through contaminated grains, with emerging risks highlighted in 2024-2025 reports due to climate-driven increases in cereal infections. Pathogenic mechanisms across hosts include adhesion via hydrophobin proteins that facilitate surface attachment, toxin production such as beauvericin which disrupts ion channels and induces apoptosis, and immune evasion strategies like protease inhibitors that counteract host defenses. Epidemiological patterns show that outbreaks of Hypocreales pathogens are favored by humid, warm climates, which promote germination and dispersal, leading to amplified impacts on through crop failures and on via altered trophic interactions in infected ecosystems. For instance, Fusarium wilt epidemics in tropical regions have caused yield reductions of up to 75% in susceptible crops during prolonged wet seasons.

Industrial and Medical Applications

Species of Hypocreales, particularly those in the genus , serve as effective biocontrol agents against fungal pathogens in through mechanisms such as mycoparasitism and for nutrients, thereby reducing reliance on synthetic pesticides. For instance, strain T-22 is the active ingredient in commercial products like RootShield, which protects plant roots from soil-borne diseases caused by pathogens such as , , and Rhizoctonia, promoting healthier crop growth and yield. These applications have been widely adopted in to minimize environmental impacts from chemical inputs. Entomopathogenic fungi within Hypocreales, including and , are formulated into biopesticides that infect and kill insect pests, offering sustainable alternatives to chemical insecticides. These fungi have been successfully deployed for locust control, where formulations disrupt swarms by causing lethargy and mortality in nymphs and adults, as demonstrated in field trials across and . As of 2025, advancements include nano-encapsulation techniques using nanoparticles that enhance spore viability, UV protection, and targeted delivery, improving efficacy against pests like ticks and agricultural insects. Hypocreales species, notably Hypocrea jecorina (the teleomorph of ), are major sources of such as cellulases and chitinases used in production and waste degradation. Cellulases from H. jecorina break down into fermentable sugars, enabling efficient bioethanol conversion and addressing key bottlenecks in . Chitinases produced by species hydrolyze in fungal cell walls and exoskeletons, facilitating applications in biocontrol and processing, with optimized strains patented in the 2020s for enhanced stability and activity. In medical applications, Hypocreales-derived secondary metabolites have significant therapeutic value; for example, cyclosporin A, an produced by (Hypocreales), prevents organ transplant rejection and treats autoimmune disorders by inhibiting T-cell activation. Additionally, species like yield antifungal compounds such as cordymin, which exhibit activity against pathogenic yeasts and molds, supporting development of novel antimicrobials amid rising resistance concerns. Ongoing research frontiers in Hypocreales focus on genetic engineering to boost metabolite and enzyme yields, including CRISPR-based modifications in Trichoderma reesei that upregulate cellulase genes for 2-3 fold higher production in industrial fermenters. In 2025, studies on the family Bionectriaceae highlight untapped commercial potential, with genera like Clonostachys engineered for improved biocontrol and biodegradation of plastics, paving the way for scalable applications in agriculture and environmental remediation.

References

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