Biosurfactant from Bacillus subtilis UCP 1533: Characterization & Powerful #pencis #researchawards

Introduction

The growing threat of antimicrobial resistance (AMR) has intensified the global demand for safe, biodegradable, and sustainable antimicrobial agents. Microbial biosurfactants have emerged as powerful alternatives due to their structural diversity, environmental compatibility, and broad-spectrum biological functions. Among these, biosurfactants produced by Bacillus subtilis have attracted significant attention because of their robust activity, low toxicity, and resilience under harsh environmental conditions. This study explores the biosurfactant synthesized by Bacillus subtilis UCP 1533, isolated from Brazilian semiarid soil, and demonstrates its promising physicochemical properties, biological stability, and effective antimicrobial potential against resistant bacterial and fungal pathogens.

Optimization of Culture Conditions for Biosurfactant Production

Optimizing culture media is crucial for maximizing biosurfactant yield and functional performance. This research evaluated multiple carbon sources, including glucose, soybean oil, molasses, and waste frying oil, alongside various nitrogen sources such as ammonium chloride, sodium nitrate, urea, and peptone. The most efficient formulation was a mineral medium enriched with 2% soybean oil and 0.12% corn steep liquor, supporting the synthesis of 16 g·L⁻¹ of biosurfactant. This optimization demonstrates how low-cost, sustainable substrates can significantly enhance production efficiency while reducing industrial-scale operational costs.

Physicochemical Characterization and Structural Confirmation

Comprehensive analyses were performed to determine the molecular nature and functional characteristics of the biosurfactant. Surface tension reduction assays showed an impressive decrease to 25 mN·m⁻¹, with a critical micelle concentration (CMC) of 0.3 g·L⁻¹, indicating high surface activity at low concentrations. FT-IR and NMR spectroscopy confirmed that the biosurfactant belongs to the lipopeptide class and possesses an anionic charge, which contributes to its stability and antimicrobial action. The emulsification index reached 100% for used motor oil, emphasizing its strong interfacial properties.

Stability Assessment Under Extreme Environmental Conditions

The biosurfactant produced by B. subtilis UCP 1533 demonstrated remarkable stability across a broad range of environmental parameters, including extreme pH, salinity, and temperature. It maintained emulsification efficiency and surface-active behavior even under conditions that typically disrupt protein- or lipid-based compounds. This resilience enhances its applicability in diverse industrial processes, such as agriculture, bioremediation, and pharmaceuticals, where operational conditions may vary widely.

Toxicity and Phytotoxicity Evaluation for Eco-Safety

Safety assessments included toxicity testing in Tenebrio molitor larvae, which exhibited 100% survival at all tested biosurfactant concentrations, confirming its non-toxic nature. Additionally, seed germination tests performed with Solanum lycopersicum and Lactuca sativa recorded rates above 90%, indicating minimal phytotoxicity. These findings support the suitability of this biosurfactant for agricultural applications, especially those requiring direct interaction with plant tissues or soil ecosystems.

Antimicrobial Efficacy Against Resistant Pathogens

The biosurfactant showed notable inhibitory effects against antimicrobial-resistant strains of Escherichia coli and Pseudomonas aeruginosa, as well as multiple Candida species, including C. glabrata, C. lipolytica, C. bombicola, and C. guilliermondii. This broad-spectrum activity highlights its potential as a natural antimicrobial agent for combating AMR-related infections. Its demonstrated efficacy against both bacterial and fungal pathogens makes it valuable for developing pharmaceutical formulations, environmental sanitizers, and sustainable plant-protection solutions.

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Hashtags

#BiosurfactantResearch, #BacillusSubtilis, #AntimicrobialResistance, #LipopeptideBiosurfactant, #MicrobialBiotechnology, #SustainableAntimicrobials, #Bioprospecting, #EnvironmentalBiotechnology, #GreenTechnology, #BiocontrolAgents, #PhytopathogenControl, #AMRSolutions, #Bioemulsifiers, #MicrobialSurfactants, #SoilMicrobiology, #IndustrialBiotechnology, #BioremediationTools, #Biopharmaceuticals, #Agrobiotechnology, #NaturalAntimicrobials,

Endobacteria Reduce Metarhizium Virulence | Microbial Interactions Explained #pencis #researchawards

                                            

Introduction

Microorganisms play a fundamental role in shaping the biology, ecology, and evolutionary trajectories of most organisms, and fungi are no exception. Fungal species exist within complex microbial networks involving plants, bacteria, viruses, and other fungi, with interactions occurring both externally around the mycelial surface and internally within the hyphae. Recent studies have revealed that many fungi harbor endobacteria (EB), which can profoundly influence their physiology, development, and ecological interactions. Members of the genus Metarhizium, common soil fungi and important entomopathogens, have only recently been recognized as hosts to EB, particularly Bacillus subtilis. Understanding how these endobacteria modulate fungal life cycles and virulence is crucial for improving the biological control potential of Metarhizium against insect pests.

Endobacteria–Fungi Symbiosis: Molecular Basis and Ecological Significance

Endobacteria residing within fungal hyphae establish a unique symbiotic system where intracellular microorganisms can directly influence host gene expression, metabolic pathways, and stress responses. In Metarhizium spp., these symbionts may modulate signaling pathways related to sporulation, nutrient acquisition, and host infection. The ecological significance of these interactions extends beyond the fungus itself, as EB-mediated changes can determine fungal competitiveness in the rhizosphere, colonization efficiency in plant roots, and interactions with other soil microbes. Research into the molecular basis of this symbiosis could provide insights into microbial evolution and potential biotechnological applications.

Influence of Bacillus subtilis Endobacteria on Metarhizium Physiology

Identifying Bacillus subtilis as an internal bacterium in Metarhizium strains opens new avenues to explore how these bacteria alter fungal physiology. EB may modulate hyphal growth, conidiation, stress tolerance, and secondary metabolite production. These physiological changes could be driven by bacterial metabolites, effector-like molecules, or nutrient exchanges occurring within the hyphae. Understanding these mechanisms is essential for unraveling the full metabolic and developmental impact of EB on fungal hosts and could help optimize fungal strains for agricultural applications.

Negative Impact of Endobacteria on Metarhizium Virulence

Experimental evidence indicates that endobacteria can reduce the entomopathogenic capacity of Metarhizium spp. against insect hosts such as Galleria mellonella and Tenebrio molitor. EB may disrupt the fungal infection process by attenuating the production of virulence factors, degrading insect cuticle-degrading enzymes, or interfering with the fungus’s ability to proliferate inside the insect hemocoel. This negative modulation challenges the assumption that intracellular bacteria always provide mutualistic benefits to their hosts, highlighting the complexity of fungal–bacterial relationships and their consequences for biological pest control.

Rhizosphere-Derived Metarhizium Strains and Their Microbial Associations

Rhizosphere-associated Metarhizium species represent a biologically rich yet understudied ecological niche. These fungi interact closely with plant roots, responding to root exudates, competing with soil microbes, and utilizing bacterial partners for nutrient cycling. The discovery of endobacteria within Metarhizium strains isolated from the rhizosphere suggests that soil and plant-associated environments may promote stable endosymbiotic relationships. Studying these microbial networks may help elucidate how rhizosphere conditions influence fungal behavior, persistence, and virulence.

Future Research Directions in Metarhizium–Endobacteria Interactions

Future studies should prioritize genomic, transcriptomic, and metabolomic analyses to uncover the mechanisms by which endobacteria alter Metarhizium virulence and development. Experimental manipulation—such as curing fungi of their EB and reintroducing them—could clarify causal relationships between bacterial presence and fungal phenotypes. Additionally, exploring EB diversity across global Metarhizium populations will help determine whether negative virulence effects are universal or strain-specific. This knowledge has practical implications for developing improved bioinsecticides with optimized efficacy and stability.

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Hashtags

#EndobacteriaResearch, #MetarhiziumFungi, #MicrobialSymbiosis, #FungalBacteriaInteraction, #BacillusSubtilis, #FungalVirulence, #EntomopathogenicFungi, #GalleriaMellonella, #TenebrioMolitor, #RhizosphereMicrobiome, #MycobiomeStudies, #FungalPathogenesis, #MicrobialEcology, #HostMicrobeInteraction, #SymbioticMicroorganisms, #FungalBiocontrol, #SoilFungiResearch, #MolecularMycology, #Endosymbionts, #InsectPathogens,