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•Lipopeptide type biosurfactant was isolated from Bacillus tequilensis strain SDS21.•Biosurfactant exhibited bactericidal and biofilm dislodging activity.•Biosurfactant removed ...biofilm from glass, stainless steel and polystyrene surface.•Exposure to extreme pH and temperature has no influence on biosurfactant activity.•Biosurfactant retained its bactericidal and anti-biofilm activity in hard water.
Antiseptics and disinfectants are widely applied for eliminating microorganisms. However, microorganisms dwelling in the biofilm are less susceptible and in some cases resistant to biocide treatment. The present study describes isolation and characterization of lipopeptide biosurfactant exhibiting disinfectant-like activity. Biosurfactant was produced by an endo-rhizospheric bacterium Bacillus tequilensis strain SDS21. Biosurfactant reduced the surface tension of water from 72 to 30 mN/m with CMC of 40 mg/l. The Liquid Chromatography–Mass Spectrometry analysis of biosurfactant suggested it to be a mixture of C14, C15, C16 and C17 surfactin homologues. The lipopeptide biosurfactant exhibited bactericidal activity against planktonic cells and biofilm residing sessile cells. The biosurfactant treatment eradicated more than 99% of bacterial biofilm present on polystyrene, glass and stainless steel surface. The biosurfactant retained its bactericidal and biofilm eradicating activities even after exposure to extreme conditions like high temperate and extreme pH. Unlike some of the commonly used disinfectant, biosurfactant retained its bactericidal and biofilm removing activity even in the hard water containing Mg2+ and Ca2+ ions. Thus, suggesting that biosurfactant produced by strain SDS21 can be used as a disinfectant or in disinfectant-like formulations effective against both planktonic and biofilm residing bacteria.
The present paper deals with the preparation and annotation of a surfactin(s) derived from a culture of the endophytic bacterium Bacillus 15 F. The LC-MS analysis of the acetonitrile fraction ...confirmed the presence of surfactins Leu/Ile7 C15, Leu/Ile7 C14 and Leu/Ile7 C13 with M+H+ at m/z 1036.6895, 1022.6741 and 1008.6581, respectively. Various concentrations of the surfactin(s) (hereafter referred to as surfactin-15 F) were used to reduce the adhesion of Staphylococcus epidermidis S61, which served as a model for studying antibiofilm activity on polystyrene surfaces. Incubation of Staphylococcus epidermidis S61 with 62.5 µg/ml of surfactin-15 F resulted in almost complete inhibition of biofilm formation (90.3 ± 3.33 %), and a significant reduction of cell viability (resazurin-based fluorescence was more than 200 times lower). The antiadhesive effect of surfactin-15 F was confirmed by scanning electron microscopy. Surfactin-15 F demonstrated an eradication effect against preformed biofilm, causing severe disruption of Staphylococcus epidermidis S61 biofilm structure and reducing viability. The results suggest that surfactins produced by endophytic bacteria could be an alternative to synthetic products. Surfactin-15 F, used in wound dressings, demonstrated an efficient treatment of the preformed Staphylococcus epidermidis S61 biofilm, and thus having a great potential in medical applications.
•Production of surfactin fraction (C13, C14 and C15 surfactin) from the endophytic bacterium Bacillus-15 F strain.•Antibacterial activities of surfactin-15 F fraction against Gram-positive and Gram-negative bacterial strains.•Ability of surfactin-15 F to inhibit and to eradicate Staphylococcus epidermidis biofilm.•Development of surfactin-containing dressings, which showed interesting antibiofilm activity.
The potential of the Bacillus genus to antagonize phytopathogens is associated with the production of cyclic lipopeptides. Depending upon the type of lipopeptide, they may serve as biocontrol agents ...that are eco-friendly alternatives to chemical fertilizers. This study evaluates the biocontrol activity of surfactin-producing Bacillus (SPB) strains NH-100 and NH-217 and purified surfactin A from these strains against rice bakanae disease. Biologically active surfactin fractions were purified by HPLC, and surfactin A variants with chain lengths from C12 to C16 were confirmed by LCMS-ESI. In hemolytic assays, a positive correlation between surfactin A production and halo zone formation was observed. The purified surfactin A had strong antifungal activity against Fusarium oxysporum, F. moniliforme, F. solani, Trichoderma atroviride and T. reesei. Maximum fungal growth suppression (84%) was recorded at 2000 ppm against F. moniliforme. Surfactin A retained antifungal activity at different pH levels (5–9) and temperatures (20, 50 and 121 °C). Hydroponic and pot experiments were conducted to determine the biocontrol activity of SPB strains and the purified surfactin A from these strains on Super Basmati rice. Surfactin production in the rice rhizosphere was detected by LCMS-ESI at early growth stages in hydroponics experiments inoculated with SPB strains. However, the maximum yield was observed with a consortium of SPB strains (T4) and purified surfactin A (T5) treatments in the pot experiment. The outcomes of the present study revealed that surfactin A significantly reduced rice bakanae disease by up to 80%. These findings suggest that purified surfactin A could be an effective biocontrol agent against bakanae disease in rice and should be incorporated into strategies for disease management.
In 1968, Arima et al. discovered the heptapeptide, known as surfactin, which belongs to a family of lipopeptides. Known for its ability to reduce surface tension, it also has biological activities ...such as antimicrobial and antiviral. Its non-ribosomal synthesis mechanism was later discovered (1991). Lipopeptides represent an important class of surfactants, which can be applied in many industrial sectors such as food, pharmaceutical, agrochemicals, detergents, and cleaning products. Currently, 75% of the surfactants used in the various industrial sectors are from the petrochemical industry. Nevertheless, there are global current demands (green chemistry concept) to replace the petrochemical products with environmentally friendly products, such as surfactants by biosurfactants. The production biosurfactants still are costly. Thus, an alternative to reduce the production costs is using agro-industrial waste as a culture medium associated with an efficient and scalable purification process. This review puts a light on the agro-industrial residues used to produce surfactin and the techniques used for its recovery.
This study explores beneficial bacteria isolated from the roots and rhizosphere soil of Khao Rai Leum Pua Phetchabun rice plants. A total of 315 bacterial isolates (KK001 to KK315) were obtained. ...Plant growth-promoting traits (phosphate solubilization and indole-3-acetic acid (IAA) production), and antimicrobial activity against three rice pathogens (Curvularia lunata NUF001, Bipolaris oryzae 2464, and Xanthomonas oryzae pv. oryzae) were assessed. KK074 was the most prolific in IAA production, generating 362.6 ± 28.0 μg/ml, and KK007 excelled in tricalcium phosphate solubilization, achieving 714.2 ± 12.1 μg/ml. In antimicrobial assays using the dual culture method, KK024 and KK281 exhibited strong inhibitory activity against C. lunata, and KK269 was particularly effective against B. oryzae. In the evaluation of antimicrobial metabolite production, KK281 and KK288 exhibited strong antifungal activities in cell-free supernatants. Given the superior performance of KK281, taxonomically identified as Bacillus sp. KK281, it was investigated further. Lipopeptide extracts from KK281 had significant antimicrobial activity against C. lunata and a minimum inhibitory concentration (MIC) of 3.1 mg/ml against X. oryzae pv. oryzae. LC-ESI-MS/MS analysis revealed the presence of surfactin in the lipopeptide extract. The crude extract was non-cytotoxic to the L-929 cell line at tested concentrations. In conclusion, the in vitro plant growth-promoting and disease-controlling attributes of Bacillus sp. KK281 make it a strong candidate for field evaluation to boost plant growth and manage disease in upland rice.
Biosurfactants comprise a wide array of amphiphilic molecules synthesized by plants, animals, and microbes. The synthesis route dictates their molecular characteristics, leading to broad structural ...diversity and ensuing functional properties. We focus here on low molecular weight (LMW) and high molecular weight (HMW) biosurfactants of microbial origin. These are environmentally safe and biodegradable, making them attractive candidates for applications spanning cosmetics to oil recovery. Biosurfactants spontaneously adsorb at various interfaces and self-assemble in aqueous solution, resulting in useful physicochemical properties such as decreased surface and interfacial tension, low critical micellization concentrations (CMCs), and ability to solubilize hydrophobic compounds. This review highlights the relationships between biosurfactant molecular composition, structure, and their interfacial behavior. It also describes how environmental factors such as temperature, pH, and ionic strength can impact physicochemical properties and self-assembly behavior of biosurfactant-containing solutions and dispersions. Comparison between biosurfactants and their synthetic counterparts are drawn to illustrate differences in their structure-property relationships and potential benefits. Knowledge of biosurfactant properties organized along these lines is useful for those seeking to formulate so-called green or natural products with novel and useful properties.
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•Biosurfactants are amphiphiles of microbial origin with surface active properties.•Biosurfactant solution self-assembly is modulated by pH, T, and ionic strength.•Diverse chemical structure/composition is reflected in solution association.•Surfactant properties of biosurfactants can be superior to synthetic surfactants.•Biosurfactants show promise in bioremediation, oil recovery, and pharmaceuticals.
The biosynthesis of surfactin has attracted broad interest; however, there is a bottleneck in its low yield in wild strains and the ability to engineer Bacillus producers. Because the key metabolic ...mechanisms in the surfactin synthesis pathway remain unclear, genetic engineering approaches are all ending up with a single or a few gene modifications. The aim of this study is to develop a systematic engineering approach to improve the biosynthesis of surfactin. First, we restored surfactin biosynthetic activity by integrating a complete sfp gene into the nonproducing Bacillus subtilis 168 strain and obtained a surfactin titer of 0.4 g/l. Second, we reduced competition by deleting biofilm formation-related genes and nonribosomal peptide synthetases/polyketide synthase pathways (3.8% of the total genome), which increased the surfactin titer by 3.3-fold. Third, we improved cellular tolerance to surfactin by overexpressing potential self-resistance-associated proteins, which further increased the surfactin titer by 8.5-fold. Fourth, we increased the supply of precursor branched-chain fatty acids by engineering the branched-chain fatty acid biosynthesis pathway, resulting in an increase of the surfactin titer to 8.5 g/l (a 20.3-fold increase). Finally, due to the preference of the glycolytic pathway for cell growth, we diverted precursor acetyl-CoA away from cell growth to surfactin biosynthesis by enhancing the transcription of srfA. The final surfactin titer increased to 12.8 g/l, with a yield of 65.0 mmol/mol sucrose (42% of the theoretical yield) in the metabolically engineered strain. To the best of our knowledge, this is the highest titer and yield that has been reported. This study may pave the way for the commercial production of green surfactin. More broadly, our work presents another successful example of the modularization of metabolic pathways for improving titer and yield in biotechnological production.
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•A systematical engineering approach was developed for surfactin production.•53 genes were spontaneously modified in B. subtilis 168 for surfactin production.•Surfactin titer reached a highest value of 12.8 g/l.•Surfactin yield reached 65.0 mmol/mol sucrose, about 42% of the theoretical yield.
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•Surfactin A was introduced into GelMA network via forming hydrogen bonds.•The hydrogel has attractive compression and self-healing properties.•The hydrogel enhances wound healing ...process and quality in diabetic rats.•The mechanisms involve the promotion of macrophage polarization and angiogenesis.
Chronic wound healing is a severe complication that threatens the life of diabetic patients because of the damaged skin microvasculature and prolonged inflammation at the wound site. Novel wound dressing materials with the outstanding wound repair specialty are highly needed. Herein, a new hydrogel was developed with attractive capabilities in stiffness, swelling, self-healing, and biocompatibility, for the treatment of chronic wound in diabetes. The hybrid hydrogel was achieved by firstly synthesizing gelatin methacrylate (GelMA), then microbial lipopeptide-surfactin (SF) together with the photoinitiator were added before being crosslinked with 60 s of UV (i.e., GelMA-SF hydrogels). With the increase of SF concentrations, the porosity and tensile modulus of GelMA-SF hydrogels decreased, while the ultimate stress and compression modulus significantly increased compared with GelMA hydrogels. The feasibility of GelMA-SF hydrogels was tested by treating skin wounds in type I diabetic rats without coverage in vivo. For the first time, the study introduced SF to the GelMA network and revealed the mechanisms of the GelMA-SF hydrogels to promote diabetic wound healing via regulating macrophage polarization and promoting angiogenesis. The dynamic multifunctional hydrogel materials show great promise in the regeneration of difform wounds, especially, in situations with impaired angiogenesis and persistent inflammatory responses.
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