Enhanced low-cost lipopeptide biosurfactant production by Bacillus velezensis from residual glycerin.

Biosurfactants (BSFs) are molecules produced by microorganisms from various carbon sources, with applications in bioremediation and petroleum recovery. However, the production cost limits large-scale applications. This study optimized BSFs production by Bacillus velezensis (strain MO13) using residual glycerin as a substrate. The spherical quadratic central composite design (CCD) model was used to standardize carbon source concentration (30 g/L), temperature (34 °C), pH (7.2), stirring (239 rpm), and aeration (0.775 vvm) in a 5-L bioreactor. Maximum BSFs production reached 1527.6 mg/L of surfactins and 176.88 mg/L of iturins, a threefold increase through optimization. Microbial development, substrate consumption, concentration of BSFs, and surface tension were also evaluated on the bioprocess dynamics. Mass spectrometry Q-TOF-MS identified five surfactin and two iturin isoforms produced by B. velezensis MO13. This study demonstrates significant progress on BSF production using industrial waste as a microbial substrate, surpassing reported concentrations in the literature.

Biological Control of Avocado Branch Blight Caused by Lasiodiplodia theobromae Using Bacillus velezensis.

In recent years, avocado branch blight has gradually become one of the major diseases causing mortality of avocado trees, which seriously affects the economic development of avocado planting regions. In order to investigate the cause of the disease, the pathogens were isolated from the interroot of avocado trees with the onset of the disease and identified as Lasiodiplodia theobromae. At the same time, three Bacillus velezensis strains, YK194, YK201, and YK268, with better antagonistic effects and high stability against L. theobromae, were isolated from the rhizospheric soil of healthy avocado plants. The results of branch experiments and field trials showed that the avocado leaves as well as branches treated with the strains YK194, YK201, and YK268 did not develop disease, and the incidence of avocado trees was significantly reduced. In the branch experiments, the biological control effect of the strains YK194, YK201, and YK268 reached 62.07, 52.70, and 72.45%, respectively. In the field experiments, it reached 63.85, 63.43, and 73.86%, respectively, which indicated that all these three strains possessed good biological control effects on avocado branch blight. Further investigation on the mechanism of action of antagonistic strains revealed that B. velezensis YK268 could produce lipopeptides, namely, surfactin, fengycin, and iturin, which could significantly inhibit the spore germination of L. theobromae. Consequently, these three isolates have potential as biocontrol agents against L. theobromae.

Safety assessment of surfactin-producing Bacillus strains and their lipopeptides extracts in vitro and in vivo.

Beneficial Bacillus strains can be administered to livestock as probiotics to improve animal health. Cyclic lipopeptides produced by Bacillus such as surfactins may be responsible for some of the beneficial effects due to their anti-inflammatory and immunomodulatory activity. The aim of the present study was to isolate and evaluate the biocompatibility of native Bacillus spp. strains and their surfactin-like lipopeptides in vitro and in vivo to determine their potential to be used on animals. Biocompatibility of endospore suspensions (108 UFC/mL), and different dilutions (1:10; 1:50; 1:100; 1:500, and 1:1000) of Bacillus lipopeptide extracts containing surfactin was tested on Caco-2 cells by microculture tetrazolium-based colorimetric assay. Genotoxicity was tested on BALB/c mice (n = 6) administered 0.2 mL of endospore suspensions by the bone marrow erythrocyte micronuclei assay. All the isolates tested produced between 26.96 and 239.97 µg mL- 1 of surfactin. The lipopeptide extract (LPE) from isolate MFF1.11 demonstrated significant cytotoxicity in vitro. In contrast, LPE from MFF 2.2; MFF 2.7, TL1.11, TL 2.5, and TC12 had no cytotoxic effect (V% > 70%) on Caco-2 cells, not affecting cell viability signifficantly in most treatments. Similarly, none of the endospore suspensions affected cell viability (V% > 80%). Likewise, endospores did not cause genotoxicity on BALB/c mice. This study was elementary as a first step for a new line of research, since it allowed us to choose the safest isolates to keep working on the search of new potentially probiotic strains destined to production animals to improve their performance and health.

Assessment of micafungin dosage regimens against Candida spp. in pediatric patients undergoing hematopoietic stem cell transplantation: a pharmacokinetic/pharmacodynamic analysis using Monte Carlo simulation.

The objective of this study was to evaluate the efficacy of various micafungin dosing regimens against Candida spp. in pediatric patients undergoing hematopoietic stem cell transplantation (HSCT). Monte Carlo simulations were conducted using pharmacokinetic (PK) parameters and pharmacodynamic (PD) data to determine the probabilities of target attainment and cumulative fractions of response in terms of area under the concentration curve/minimum inhibition concentration targets of micafungin. Current standard clinical micafungin dosing regimens of 1 and 2 mg/kg/day were appropriate for the prevention and treatment of Candida glabrata infection in pediatric patients undergoing HSCT, respectively. Moreover, the high-dose prophylactic dosage (2 mg/kg/day) and therapeutic dosage (4 mg/kg/day) should be the preferred option to optimize efficacy against Candida albicans. However, none of the simulated regimens was effective against Candida parapsilosis in pediatric HSCT patients. These PK/PD-based simulations rationalize and optimize the micafungin dosing regimens against Candida spp. in pediatric patients undergoing HSCT.

Assessment of the Impact of a Toll-like Receptor 2 Agonist Synthetic Lipopeptide on Macrophage Susceptibility and Responses to African Swine Fever Virus Infection.

Toll-like receptor 2 (TLR2) ligands are attracting attention as prophylactic and immunopotentiator agents against pathogens, including viruses. We previously reported that a synthetic diacylated lipopeptide (Mag-Pam2Cys_P48) polarized porcine macrophages towards a proinflammatory antimicrobial phenotype. Here, we investigated its role in modulating monocyte-derived macrophage (moMΦ) responses against African swine fever virus (ASFV), the etiological agent of one of the greatest threats to the global pig industry. Two ASFV isolates were compared: the attenuated NH/P68 and the virulent 26544/OG10. No effect on virus infection nor the modulation of surface markers' expression (MHC I, MHC II DR, CD14, CD16, and CD163) were observed when Mag-Pam2Cys_P48 treated moMΦ were infected using a multiplicity of infection (MOI) of 1. Mag-Pam2Cys_P48 treated moMΦ released higher levels of IL-1α, IL-1ß, IL-1Ra, and IL-18 in response to infection with NH/P68 ASFV compared to 26544/OG10-infected and mock-infected controls. Surprisingly, when infected using a MOI of 0.01, the virulent ASFV 26544/OG10 isolate replicated even slightly more efficiently in Mag-Pam2Cys_P48 treated moMΦ. These effects also extended to the treatment of moMΦ with two other lipopeptides: Mag-Pam2Cys_P80 and Mag-Pam2Cys_Mag1000. Our data suggested limited applicability of TLR2 agonists as prophylactic or immunopotentiator agents against virulent ASFV but highlighted the ability of the virulent 26544/OG10 to impair macrophage defenses.

Cost-utility analysis of caspofungin and fluconazole for primary treatment of invasive candidiasis and candidemia in Ethiopia.

BACKGROUND: Invasive candidiasis and/or candidemia (IC/C) is a common fungal infection leading to significant health and economic losses worldwide. Caspofungin was shown to be more effective than fluconazole in treating inpatients with IC/C. However, cost-effectiveness of caspofungin for treating IC/C in Ethiopia remains unknown. We aimed to assess the cost-utility of caspofungin compared to fluconazole-initiated therapies as primary treatment of IC/C in Ethiopia. METHODS: A Markov cohort model was developed to compare the cost-utility of caspofungin versus fluconazole antifungal agents as first-line treatment for adult inpatients with IC/C from the Ethiopian health system perspective. Treatment outcome was categorized as either a clinical success or failure, with clinical failure being switched to a different antifungal medication. Liposomal amphotericin B (L-AmB) was used as a rescue agent for patients who had failed caspofungin treatment, while caspofungin or L-AmB were used for patients who had failed fluconazole treatment. Primary outcomes were expected quality-adjusted life years (QALYs), costs (US$2021), and the incremental cost-utility ratio (ICUR). These QALYs and costs were discounted at 3% annually. Cost data was obtained from Addis Ababa hospitals while locally unavailable data were derived from the literature. Cost-effectiveness was assessed against the recommended threshold of 50% of Ethiopia's gross domestic product/capita (i.e.,US$476). Deterministic and probabilistic sensitivity analyses were conducted to assess the robustness of the findings. RESULTS: In the base-case analysis, treatment of IC/C with caspofungin as first-line treatment resulted in better health outcomes (12.86 QALYs) but higher costs (US$7,714) compared to fluconazole-initiated treatment followed by caspofungin (12.30 QALYs; US$3,217) or L-AmB (10.92 QALYs; US$2,781) as second-line treatment. Caspofungin as primary treatment for IC/C was not cost-effective when compared to fluconazole-initiated therapies. Fluconazole-initiated treatment followed by caspofungin was cost-effective for the treatment of IC/C compared to fluconazole with L-AmB as second-line treatment, at US$316/QALY gained. Our findings were sensitive to medication costs, drug effectiveness, infection recurrence, and infection-related mortality rates. At a cost-effectiveness threshold of US$476/QALY, treating IC/C patient with fluconazole-initiated treatment followed by caspofungin was more likely to be cost-effective in 67.2% of simulations. CONCLUSION: Our study showed that the use of caspofungin as primary treatment for IC/C in Ethiopia was not cost-effective when compared with fluconazole-initiated treatment alternatives. The findings supported the use of fluconazole-initiated therapy with caspofungin as a second-line treatment for patients with IC/C in Ethiopia.

Formulation of a glycolipid:lipopeptide mixture as biosurfactant-based dispersant and development of a low-cost glycolipid production process.

Biosurfactant-based dispersants were formulated by mixing glycolipids from Weissella cibaria PN3 and lipopeptides from Bacillus subtilis GY19 to enhance the synergistic effect and thereby achieve hydrophilic-lipophilic balance. The proportions of each biosurfactant and dispersant-to-oil ratios (DORs) were varied to obtain the appropriated formulations. The most efficient glycolipid:lipopeptide mixtures (F1 and F2) had oil displacement activities of 81-88% for fuel and crude oils. The baffled flask test of these formulations showed 77-79% dispersion effectiveness at a DOR of 1:25. To reduce the cost of the dispersant, this study optimized the glycolipid production process by using immobilized cells in a stirred tank fermenter. Semicontinuous glycolipid production was carried out conveniently for 3 cycles. Moreover, food wastes, including waste coconut water and waste frying oil, were found to promote glycolipid production. Glycolipids from the optimized process and substrates had similar characteristics but 20-50% lower cost than those produced from basal medium with soybean oil in shaking flasks. The lowest cost dispersant formulation (F2*) contained 10 g/L waste-derived cell-bound glycolipid and 10 g/L lipopeptide and showed high dispersion efficiency with various oils. Therefore, this biosurfactant-based dispersant could be produced on a larger scale for further application.

Assessment of nonreleasing antifungal surface coatings bearing covalently attached pharmaceuticals.

There are many reports of antimicrobial coatings bearing immobilized active agents on surfaces; however, strong analytical evidence is required to verify that the agents are indeed covalently attached to the surface. In the absence of such evidence, antimicrobial activity could result from a release of active agents. We report a detailed assessment of antifungal surface coatings prepared using covalent attachment chemistries, with the aim of establishing a set of instrumental and biological evidence required to convincingly demonstrate antimicrobial activity due to nonreleasing, surface active compounds and to exclude the alternate possibility of activity due to release. The strongest biological evidence initially supporting permanent antifungal activity was the demonstration of the ability to reuse samples in multiple, sequential pathogen challenges. However, additional supporting evidence from washing studies and instrumental analysis is also required to probe the possibility of gradual desorption of strongly physisorbed compounds versus covalently attached compounds. Potent antifungal surface coatings were prepared from approved pharmaceutical compounds from the echinocandin drug class (caspofungin, anidulafungin, and micafungin) and assessed by microbiological tests and instrumental methods. Carbonyl diimidazole linking chemistry enabled covalent attachment of caspofungin, anidulafungin, and micafungin to plasma polymer surfaces, with antifungal surface activity likely caused by molecular orientations that present the lipophilic tail toward interfacing fungal cells. This study demonstrates the instrumental and biological evidence required to convincingly ascertain activity due to nonreleasing, surface active compounds and summarize these as three criteria for assessing other reports on surface-immobilized antimicrobial compounds.

Prospective Cohort Study of Micafungin Population Pharmacokinetic Analysis in Plasma and Peritoneal Fluid in Septic Patients with Intra-abdominal Infections.

The objective of this study was to describe the pharmacokinetics (PK) of micafungin in plasma and peritoneal fluid in septic patients with intra-abdominal infections. Twelve patients with secondary peritonitis in septic shock receiving 100 mg micafungin once daily were included. Total micafungin plasma and peritoneal fluid were subjected to a population pharmacokinetic analysis using Pmetrics. Monte Carlo simulations were performed considering the total area under the curve from 0 to 24 h (AUC0-24)/MIC ratios in plasma. Micafungin concentrations in both plasma and the peritoneal exudate were best described by a three-compartmental PK model with the fat-free mass (FFM) as a covariate of clearance (CL) and the volume of the central compartment (Vc). The mean parameter estimates (standard deviations [SD]) were 1.18 (0.40) liters/h for CL and 12.85 (4.78) liters for Vc. The mean peritoneal exudate/plasma ratios (SD) of micafungin were 25% (5%) on day 1 and 40% (8%) between days 3 and 5. Dosing simulations supported the use of standard 100-mg daily dosing for Candida albicans (FFM, <60 kg), C. glabrata (FFM, <50 kg), and C. tropicalis (FFM, <30 kg) on the second day of therapy. There is a moderate penetration of micafungin into the peritoneal cavity (25 to 40%). For empirical treatment, a dose escalation of at least a loading dose of 150 mg depending on the FFM of patients and the Candida species is suggested to be effective from the first day of therapy.

Kinetic modeling and quasi-economic analysis of fermentative glycolipopeptide biosurfactant production in a medium co-optimized by statistical and neural network approaches.

This study presents the kinetics of production of a glycolipopeptide biosurfactant in a medium previously co-optimized by response surface and neural network methods to gain some insight into its volumetric and specific productivities for possible scale-up towards industrial production. Significant kinetic parameters including maximum specific growth rate, µmax, specific substrate consumption rate, qs and specific biosurfactant yield, Yp/x were determined from logistic model parameters after comparison with other kinetic models. Results showed that bio-catalytic rates of lipase and urease reached exponential values within the first 12 h of fermentation leading to high specific rates of substrate consumption and bacterial growth. Volumetric biosurfactant production reached significantly high levels during prolonged stationary growth and specific urease activity. This suggests that glycolipopeptide biosynthesis may proceed through stationary phase transpeptidation of the glycolipid base. A high cross-correlation coefficient of 0.950 confirmed that substrate consumption and glycolipopeptide production occurred contemporaneously during the 66-h fermentation. The maximum biosurfactant concentration of 132.52 g/L, µmax of 0.292 h-1, qp of 1.674 g/gDCW/h, rp of 2.008 g/(Lh) and Yp/x of 4.413 g/g predicted by the selected logistic model and a unit cost of €0.57/g glycolipopeptide in the optimized medium may lead to technical and economic benefits.

Immunogenicity Assessment of Cell Wall Carbohydrates of Group A Streptococcus via Self-Adjuvanted Glyco-lipopeptides.

Identifying the immunogenic moieties and their precise structure of carbohydrates plays an important role for developing effective carbohydrate-based subunit vaccines. This study assessed the structure-immunogenicity relationship of carbohydrate moieties of a single repeating unit of group A carbohydrate (GAC) present on the cell wall of group A Streptococcus (GAS) using a rationally designed self-adjuvanted lipid-core peptide, instead of a carrier protein. Immunological evaluation of fully synthetic glyco-lipopeptides (particle size: 300-500 nm) revealed that construct consisting of higher rhamnose moieties (trirhamnosyl-lipopeptide) was able to induce enhanced immunogenic activity in mice, and GlcNAc moiety was not found to be an essential component of immunogenic GAC mimicked epitope. Trirhamnosyl-lipopeptide also showed 75-97% opsonic activity against four different clinical isolates of GAS and was comparable to a subunit peptide vaccine (J8-lipopeptide) which illustrated 65-96% opsonic activity.

Impact of Loading Dose of Caspofungin in Pharmacokinetic-Pharmacodynamic Target Attainment for Severe Candidiasis Infections in Patients in Intensive Care Units: the CASPOLOAD Study.

This study evaluated the impact of a high loading dose of caspofungin (CAS) on the pharmacokinetics of CAS and the pharmacokinetic-pharmacodynamic (PK-PD) target attainment in patients in intensive care units (ICU). ICU patients requiring CAS treatment were prospectively included to receive a 140-mg loading dose of CAS. Plasma CAS concentrations (0, 2, 3, 5, 7, and 24 h postinfusion) were determined to develop a two-compartmental population PK model. A Monte Carlo simulation was performed and the probabilities of target attainment (PTAs) were computed using previously published MICs. PK-PD targets were ratios of area under the concentration-time curve from 0 to 24 h (AUC0-24h) divided by the MIC (AUC0-24h/MIC) of 250, 450, and 865 and maximal concentration (Cmax) divided by the MIC (Cmax/MIC) of 5, 10, 15, and 20. Among 13 included patients, CAS clearance was 0.98 ± 0.13 liters/h and distribution volumes were V1 = 9.0 ± 1.2 liters and V2 = 11.9 ± 2.9 liters. Observed and simulated CAS AUC0-24h were 79.1 (IQR 55.2; 108.4) and 81.3 (IQR 63.8; 102.3) mg · h/liter during the first 24 h of therapy, which is comparable to values usually observed in ICU patients at day 3 or later. PTAs were >90% for MICs of 0.19 and 0.5 mg/liter, considering AUC/MIC = 250 and Cmax/MIC = 10 as PK-PD targets, respectively. Thus, a high loading dose of CAS (140 mg) increased CAS exposure in the first 24 h of therapy, allowing early achievement of PK-PD targets for most Candida strains. Such a strategy seems to improve treatment efficacy, though further studies are needed to assess the impact on clinical outcomes. (This study has been registered at ClinicalTrials.gov under identifier NCT02413892.).

Biotechnological Applications of Paenibacillus sp. D9 Lipopeptide Biosurfactant Produced in Low-cost Substrates.

The present study assesses the Paenibacillus sp. D9 lipopeptide biosurfactant synthesis in cheap substrates including functional properties and applicability for varying biotechnological processes. Different experimental setups were made for oil dispersion, heavy metals removals from contaminated environments, and washing performance. The study revealed surface tension activities of 31.7-32.7 mN/m, and maximum biosurfactant yield of more than 8 g/L. Removals of 85.90%, 98.68%, 99.97%, 63.28%, 99.93%, and 94.22% were obtained for Ca, Cu, Fe, Mg, Ni, and Zn, respectively from acid mine effluents. In comparison with chemical surfactants, there was pronounced removal of heavy metals from wastewater, contaminated sands, and vegetable matter, as well as improved oil dispersing activity. A comparative study revealed that biosurfactant was more efficient (> 60%) for removal of tomato sauce and coffee stains than chemical surfactants (< 50%). Thus, lipopeptide biosurfactants are green biomolecules reducing hazards and contaminations within the environment. The future use of this lipopeptide biosurfactant is greatly promising in biotechnology.

Impact assessment of azulene and chromium on growth and metabolites of wheat and chilli cultivars under biosurfactant augmentation.

Dye azulene and heavy metal chromium are two different types of persistent toxic compounds present in textile effluent. These compounds contaminate the soil and harm plant productivity during unchecked disposal of textile effluent to the farm soil. Environmental and safety concerns associated with crops, soil, and human health encourage the exploration of biological tools to control the issue. We hereby propose the application of biosurfactant (lipopeptide) to reduce the toxic effects of azulene and chromium in plants. Results of the study indicated that the augmentation of biosurfactant with azulene and chromium promoted seed germination, plant biomass, specific leaf weight (SLW), chlorophyll content, protein content, soluble sugar and ascorbic acid concentration in cultivars of wheat and chilli. Decreasing the level of proline under biosurfactant augmentation further confirms the reduction of oxidative stress caused by azulene and chromium amendment. The results indicated that lipopeptide biosurfactant could be an effective biological tool to reduce the toxic effect of persistent substances in soil, thus maintaining soil health and sustainable agriculture.

Chronic hepatitis delta: A state-of-the-art review and new therapies.

Chronic delta hepatitis is the most severe form of viral hepatitis affecting nearly 65 million people worldwide. Individuals with this devastating illness are at higher risk for developing cirrhosis and hepatocellular carcinoma. Delta virus is a defective RNA virus that requires hepatitis B surface antigen for propagation in humans. Infection can occur in the form of a co-infection with hepatitis B, which can be self-limiting, vs superinfection in a patient with established hepatitis B infection, which often leads to chronicity in majority of cases. Current noninvasive tools to assess for advanced liver disease have limited utility in delta hepatitis. Guidelines recommend treatment with pegylated interferon, but this is limited to patients with compensated disease and is efficacious in about 30% of those treated. Due to limited treatment options, novel agents are being investigated and include entry, assembly and export inhibitors of viral particles in addition to stimulators of the host immune response. Future clinical trials should take into consideration the interaction of hepatitis B and hepatitis D as suppression of one virus can lead to the activation of the other. Also, surrogate markers of treatment efficacy have been proposed.

New sustainable alternatives to reduce the production costs for surfactin 50 years after the discovery.

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.

Ecotoxicological assessment of synthetic and biogenic surfactants using freshwater cladoceran species.

Surfactants have been continuously detected within aquatic environments as a consequence of their use on a global scale. Lipopeptides are biosurfactants naturally produced by Bacillus subtilis that have been explored as green alternatives. The assessment of ecotoxicological parameters of synthetic and biogenic surfactants are required for evaluating toxicity values and to verify the eco-friendly behaviour of the biological compounds. This study aimed to conduct toxicity testing for different surfactants - sodium dodecyl sulphate and Triton X-100 - and biosurfactants - surfactin, iturin and fengycin - at different concentrations using Daphnia magna as model organism and Dendrocephalus brasiliensis as alternative test species for monitoring of pollutants in tropical freshwaters. According results, both species showed high sensitivity for the anionic compound SDS concerning the recommended dosage use, exhibiting EC50-48h values of 24.1 and 15.4 mg/L for D. magna and D. brasiliensis, respectively. Although the biological source, surfactin showed the lower safety behaviour among the biogenic surfactants, while iturin and fengycin revealed very low toxicity effects on both organisms. Besides, data exhibited a higher responsiveness of D. brasiliensis for all tested compounds in comparison to D. magna, highlighting the importance of this species for monitoring of pollutants in tropical and subtropical environments.

Economic production and biocontrol efficiency of lipopeptide biosurfactants from Bacillus mojavenis A21.

In the wake of an increased attention on the eco-friendly biopesticidal products and the rising market requirements for organic agents, lipopeptides compounds have been described as biological control agents which improve the overall health growth and development of plants. Nevertheless, their high production cost constitue the major flaw in their wide use to control plant diseases. The present article aims to formulate an economic media for lipopeptides production by Bacillus mojavensis A21 for application as natural fungicides for plant disease treatment. We herein demonstrated the suitability of the potato waste, as low cost substrate, for lipopeptides production. Moreover, sea water  was found to be a good mineral salts sources. In the second part of this study, we investigate the inhibitory activity of A21 lipopeptides against the phtopathogenic Fusarium sp. The in vitro test showed a minimal inhibitory concentration of about 0.3 mg/ml. The microscopic examination, of the treated Fusarium revealed an excessive lysis of the mycelia ultrastructure with destructed spores. The in vivo antagonist activity was confirmed towards the infected potato tubers. A21 lipopeptides are effective in decreasing by about 78.26% and 60.68% when applied as preventive and curative treatments, respectively, as compared to the untreated tubers.

Performance of Bacillus subtilis on fibrous biomass sugar hydrolysates in producing biosurfactants and techno-economic comparison.

Surfactin and fatty acetyl glutamate (FA-Glu) were produced by Bacillus subtilis in 5-L fermentor. In a previous 50-mL shake flask study, sugar hydrolysates from soy hull, alfalfa and switchgrass were shown to support the growth of Bacillus strains. It was observed that glucose content and availability of hexose and pentose sugars in the hydrolysates played an important role in determining growth and product concentration. Growth, economic efficiency and product concentration of biosurfactants was compared in fermentations conducted in 5-L stirred tank bioreactor, on biomass hydrolysate-based growth media. Highest bacterial growth absorbance for surfactin and FA-Glu producing strains were at 3.5 and 3.3 absorbance units, respectively, for switchgrass hydrolysate media. Highest concentrations of products were observed in soy hull hydrolysate media (2.9 g/L and 0.28 g/L for surfactin and FA-Glu). Techno-economic analysis of the 5-L fermentations on the three biomasses showed surfactin cost estimate to be $6.63/kg for 97% pure product.