Biosurfactant Production Research Articles

Molecular characterization of biosurfactant-producing bacteria from a crude oil polluted soil in Nigeria

Most biosurfactant-producing microorganisms are hydrocarbon degraders. The research was conducted to isolate and characterize biosurfactant-producing bacteria from a crude oil polluted soil in Nigeria. Biosurfactant-producing bacteria were isolated from crude oil-polluted soil. Crude oil-polluted soil was collected by random sampling and its physicochemical analysis was done. Bacteria were isolated from the contaminated soil and screened for biosurfactant production. Organisms that showed the ability to produce biosurfactant were identified using morphological, biochemical and molecular methods. The physicochemical parameters of the soil showed a pH 6.9, electrical conductivity of 71.5, 2.55% carbon, 2.016% nitrogen and 5.98% phosphorus. The values of biosurfactant tests showed that organisms S2 and S13 were positive for biosurfactant production. The percentage emulsion indexes of the two selected organisms S2 and S13 were 59.09% and 57.14% respectively. The Blast analysis from the molecular identification showed that the isolated organisms were Gordonia alkanivorans for S2 and Tsukamurella inochensis for S13. This research showed that the isolated biosurfactant-producing bacteria are abundant in the crude oil polluted soil.

Biosurfactant and biopolymer producing microorganisms from West Kazakhstan oilfield

Microbiological enhanced oil recovery (MEOR) uses indigenous or exogenous microorganisms and nutrients to enhance oil production through synthesis of metabolites reducing oil viscosity and surface tension. In order to find bacteria suitable for MEOR, we studied 26 isolates from wells in the Akingen oilfield in West Kazakhstan. Six of them were selected for further analysis based on their ability to reduce surface tension to less than 40 mN/m, with the A9 isolate exhibiting tension reduction values of 32.76 ± 0.3 mN/m. Based on the morphological features, biochemical activities, and the 16S rRNA gene, the isolates were classified to the Bacillus subtilis group. In the phylogenetic analysis the isolates grouped into two main clusters. Genes encoding the surfactin synthetase subunits were found in A2, A8, A9, A12, PW2, only the PW2 strain had lchAA encoding lichenysin, while sacB encoding levan was noted in A2, A8, A9, and A12. The expression of srfAB, srfAC, and sacB tested with qPCR varied among strains. Nevertheless, whereas temperature moderately affects the expression level, with the highest level recorded at 40 °C, salinity significantly impacts the expression of the genes encoding biosurfactants. B. subtilis strains isolated in the study, especially A9, are promising for microbial-enhanced oil recovery.

EVALUATION OF BIOSURFACTANT PRODUCING AND ANTIMICROBIAL RESISTANCE PSEUDOMONAS FOR HEAVY METALS TOLERANCE

This study aimed to evaluate biosurfactant production and antibiotic resistance in Pseudomonas bacteria isolated from some agricultural fields to detect the relationship of these isolates traits with some heavy metals resistance. Bacterial isolates were screened for biosurfactant production through blood hemolysis, oil spreading, emulsification activity, and surface tension. The antibiotic sensitivity was determined using disk diffusion method. Then, identification of the selected isolates and subjected to gradient concentrations of heavy metals to determine the minimum inhibitory concentration (MIC). Biosurfactant production was found in 74.29% of these isolates. The isolates resistance to Ticarcillin-clavulanate, Aztreonam, Piperacillin, and Imipenem were 92.86%, 31.43%, 2.86% and 1.43%, respectively. The eight selected isolates were identified by biochemical tests and VITEK 2 system as P. aeruginosa. The resistance of these isolates to heavy metals differed significantly. The isolate B49 recorded the highest resistance to Cu (MIC=3200 µg/ml) and Zn (MIC=2600 µg/ml), while the isolate B66 recorded the highest resistance to Cd (MIC=1000 µg/ml) and isolate B25 had higher resistance to Hg (MIC=80 µg/ml), and Pb (MIC=2800 µg/ml). The correlation coefficient between emulsification (E24%) and CdCl2 (r=0.27) and Pb (r=0.38) was significant positive, while E24% had a significant negative correlation with Zn (r= -0.63) and non-significant correlation to copper (r=0.02) and mercury (r=0.19) resistance.

THE ANTIBACTERIAL ACTIVITY OF GLYCOLIPOPEPTIDE PRODUCED FROM LACTOCOCCUS LACTIS HN21 AGAINST SOME CLINICAL PATHOGENS IN COMBINED WITH SOME STANDARD ANTIBIOTICS

This study was aimed to produce a biosurfactant from Lactococcus sp. and study its synergistic effects with some standard antibiotics. Lactococcus sp. HN21 isolate was selected for its highly biosurfactant production and antibacterial activity. It was identified by 16s r RNA as Lactococcus lactis HN21. Optimum conditions for production were studied and it was: Modified M17 media (M17 media with some modifications in its composition) at ph 6.5, for 96 hrs incubation time. The E24% at these conditions was 77%. FTIR and GC-MS results identified the produced biosurfactant as glycolipopeptide with a major fatty acid octadecenoic acid. P. aeruginosa was successfully inhibited by the glycolipopeptide alone, with overall inhibition ranging from (15 to 19 mm). The combined use of antibiotics and glycolipopeptide, however, resulted in an increase in the total inhibition zones to (17 to 28 mm), while glycolipopeptide alone was effective against S. aureus and showed total inhibition zones ranging from (15 to 22) mm. glycolipopeptide in combination with antibiotics, the total inhibition zones were increased (26 to 40) mm. The results observed a great pharmaceutical application in increasing the bactericidal effect.

Isolation, identification, and characterization of potential biosurfactant-producing bacteria from processing wastewater for the development of eco-friendly green technology

Exploring novel biosurfactants (BS) has become a critical focus in biotechnology research. While BS provides eco-friendly substitutes to chemical surfactants, there is a need to identify high-potential BS-producing bacteria. Currently, the sustainable development of BS-based technologies is hindered by the lack of systematic exploration and understanding of microbial diversity for BS production. This study aims to isolate and identify novel BS isolated from different strains and elucidate their chemical structures for assessing their potential applications. Eleven BS-producing bacteria were isolated from processing wastewater (PWW). The strains were identified by 16S ribotyping and screened for BS production. The produced BS were characterized using Fourier transform infrared and nuclear magnetic resonance spectroscopic techniques. The results indicated that five strains produced a lipopeptide BS, while the other six strains produced glycolipid BS. According to the findings, eleven strains are distributed in eight genera indicating the high bacterial diversity in BS production.

Limits for sustainable biosurfactant production: Techno-economic and environmental assessment of a rhamnolipid production process

A techno-economic and environmental assessment of a di-rhamnolipid production process is presented. The process was designed based on patents describing industrial-scale glycolipid production. Glucose, glycerol, soybean oil, and stearic acid were tested as feedstocks. Maximum theoretical substrate-to-product yields were used. The simulation process was simulated using Aspen Plus v9.0. The techno-economic assessment was performed to elucidate the best feedstock. In addition, an environmental analysis was conducted using SimaPro v8.3. The highest productivity was calculated for stearic acid (3.57 kg di-rhamnolipid/t/d). The specific energy consumption and capital investment ranged from 1.8 MJ/kg to 6.1 MJ/kg and 1.8 to 2.8 M.USD, respectively. Stearic acid was identified as the most suitable raw material since the production cost was 12 USD/kg and the carbon footprint was 7.58 kgCO2-eq/kg. The environmental results elucidated that energy consumption as the most important hotspot. As conclusion, stearic acid is a promising option for producing di-rhamnolipids.

Life Cycle Assessment of Biossurfactants: A Critical Analysis

Objective: To analyze the environmental performance of biosurfactants in comparison to synthetic surfactant based on the literature. Theoretical Framework: Surfactants are used in various sectors, ranging from domestic uses to industrial applications. Their surface tension reduction properties make them efficient in cleaning and versatile, however they come predominantly from fossil sources. In contrast, biosurfactants constitute a variety of surfactants obtained by microorganisms, including yeasts, bacteria and fungi, from renewable biomass sources. Method: A systematic four-step approach was used, including advanced search, combined strings, screening and reading of abstracts, validation of results and reading and analysis of documents. The inclusion criteria were: use of environmental Life Cycle Assessment (LCA), biosurfactant study and originality. Results: 6 articles were validated and it was verified that for 1 kg of product, biosurfactants present varying environmental impacts depending on the impact categories analyzed and higher values compared to synthetic surfactant. Technological advances in the production of biosurfactants indicate a potential to increase their efficiency, making them competitive with synthetic surfactants. Research implications: This research addresses the scarcity of data on the environmental performance of biosurfactants, encouraging studies to enable their large-scale production. Life Cycle Analysis (LCA) directs technological efforts, aiming at the entry of these products into the commodities market.

Optimization of mineral nutrients to improve rhamnolipid production by Pseudomonas aeruginosa6 K‐11

AbstractBACKGROUNDRhamnolipids are biosurfactants that have their main application in bioremediation processes. They are able to increase the biodegradation and detoxification rates from industrial effluents. The north of Peru and Iquitos have been not only major oil producers but also have been responsible for oil spills. This study therefore focused on the optimization of mineral nutrients such as nitrogen, phosphorous, calcium and iron to improve rhamnolipids production by Pseudomonas aeruginosa 6 K‐11, which was isolated from oil soil in Peru.RESULTSPseudomonas aeruginosa 6 K‐11 was reactivated in Trypticase Soy Broth by scaling from 5 to 200 mL of culture medium for 8 h at each stage. The culture was centrifuged and placed in 100 mL Siegmund–Wagner medium for 36 h in a 500 mL Erlenmeyer flask. First, it was determined that sodium nitrate, monopotassium phosphate, calcium chloride and iron sulfate were the best sources of mineral nutrients. Then, by using corn oil as carbon source, the ratios obtained for carbon‐to‐nitrogen and carbon‐to‐phosphorous were 21.172 and 16.279, respectively. In addition, it was found that the optimal concentration for calcium was 0.046 g L−1 and for iron was 0.003 g L−1. The most influential variables were carbon‐to‐nitrogen and carbon‐to‐phosphorus ratio. Finally, 35.124 g L−1 rhamnolipids was produced after 168 h of fermentation with the optimal parameters.CONCLUSIONThe optimization of mineral nutrients was an important achieved goal for rhamnolipid production. In addition, this optimization can be used for modifying the culture medium to grow the biosurfactant producer strain. © 2024 Society of Chemical Industry (SCI).

Sustainable biosurfactant production from secondary feedstock-recent advances, process optimization and perspectives.

Biosurfactants have garnered increased attention lately due to their superiority of their properties over fossil-derived counterparts. While the cost of production remains a significant hurdle to surpass synthetic surfactants, biosurfactants have been anticipated to gain a larger market share in the coming decades. Among these, glycolipids, a type of low-molecular-weight biosurfactant, stand out for their efficacy in reducing surface and interfacial tension, which made them highly sought-after for various surfactant-related applications. Glycolipids are composed of hydrophilic carbohydrate moieties linked to hydrophobic fatty acid chains through ester bonds that mainly include rhamnolipids, trehalose lipids, sophorolipids, and mannosylerythritol lipids. This review highlights the current landscape of glycolipids and covers specific glycolipid productivity and the diverse range of products found in the global market. Applications such as bioremediation, food processing, petroleum refining, biomedical uses, and increasing agriculture output have been discussed. Additionally, the latest advancements in production cost reduction for glycolipid and the challenges of utilizing second-generation feedstocks for sustainable production are also thoroughly examined. Overall, this review proposes a balance between environmental advantages, economic viability, and societal benefits through the optimized integration of secondary feedstocks in biosurfactant production.

Toward Effects of Hydrophobicity on Biosurfactant Production by Bacillus subtilis Isolates from Crude-Oil-Exposed Environments

Background: Due to their structural features, biosurfactants reveal promising physicochemical properties, making them interesting for various applications in different fields, such as the food, cosmetics, agriculture, and bioremediation sectors. In particular, the bioproduction of surfactin, one of the most potent microbially synthesized biosurfactant molecules, is of great interest. However, since the wild-type productivities are comparably low, stimulatory environmental conditions have to be identified for improved bioproduction This study aims to find a correlation between the hydrophobicity and production of the biosurfactant surfactin by B. subtilis isolates from crude-oil-contaminated soil and water. Methods: The surfactin production yield was characterized in adapted batch cultivations using high-performance thin-layer liquid chromatography (HPTLC). Defined hydrophobic environmental conditions were achieved by supplementation with hexadecane or polystyrene beads, and the effects on biosurfactant production were measured. Adaptations at the protein level were analyzed using mass spectrometry measurements. Results: The correlation between hydrophobicity and surfactin production was characterized using Bacillus subtilis strains ZH1 and P7 isolated from crude-oil-contaminated soil and water. Since these isolates show the biodegradation of crude oil and hexadecane as hydrophobic substrates, respectively, a first-time approach, using polystyrene beads, was applied to provide a hydrophobic environment. Interestingly, contrary to popular opinion, reduced biosurfactant production was determined. Using mass spectrometric approaches, the physiological effects of co-cultivation and the cellular response at the protein level were investigated, resulting in altered quantities of stress proteins and proteins involved in the carbon metabolism counter to polystyrene beads. Conclusions: Contrary to common opinion, increasing hydrophobicity does not have a stimulating effect, and even reduces the effect on the bioproduction of surfactin as the main biosurfactant using selected B. subtilis strains.

Bioconversion of waste glycerol into viscosinamide by Pseudomonas fluorescens DR54 and its activity evaluation

Lipopeptides, derived from microorganisms, are promising surface-active compounds known as biosurfactants. However, the high production costs of biosurfactants, associated with expensive culture media and purification processes, limit widespread industrial application. To enhance the sustainability of biosurfactant production, researchers have explored cost-effective substrates. In this study, crude glycerol was evaluated as a promising and economical carbon source in viscosinamide production by Pseudomonas fluorescens DR54. Optimization studies using the Box − Behnken design and response surface methodology were performed. Optimal conditions for viscosinamide production including glycerol 70.8 g/L, leucine 2.7 g/L, phosphate 3.7 g/L, and urea 9.3 g/L were identified. Yield of viscosinamide production, performed under optimal conditions, reached 7.18 ± 0.17 g/L. Preliminary characterization of viscosinamide involved the measurement of surface tension. The critical micelle concentration of lipopeptide was determined to be 5 mg/L. Furthermore, the interactions between the viscosinamide and lipase from Candida rugosa (CRL) were investigated by evaluating the impact of viscosinamide on lipase activity and measuring circular dichroism. It was observed that the α-helicity of CRL increases with increasing viscosinamide concentration, while the random coil structure decreases.

Diesel−biodegradation and biosurfactant−production by Janthinobacterium lividum AQ5-29 and Pseudomonas fildesensis AQ5-41 isolated from Antarctic soil

Given the substantial diesel demand in Antarctic operations, the means of addressing ecological restoration following its inappropriate release are attracting attention from researchers. The Madrid Protocol mandates the use of indigenous microbes in bioremediation. Recent studies have proposed many native isolates with biodegradation temperatures exceeding 20 °C, which are impractical for Antarctic contexts. Therefore, harnessing psychrophilic, native degraders with biosurfactant−producing traits presents an advantage for implementation in the harsh Antarctic environment. In this study, effective consortia/isolates demonstrated robust growth and biodegradation rates at 10 °C with diesel as the sole carbon source. Two primary bacterial members, Janthinobacterium lividum and Pseudomonas fildesensis, were identified from the most effective consortium SI 20 using 16S rRNA and multilocus−sequence−analysis (MLSA) clustering. The degraders were characterised as being psychrophilic, Gram-negative, rod−shaped, and catalase− and oxidase−positive. Despite the observed antagonistic effects during co-cultivation, strains J. lividum AQ5-29 and P. fildesensis AQ5-41 demonstrated effective diesel removal (2.91 & 4.20 mg mL−1) with biodegradation of C10 to C30 hydrocarbons (40−100%) at 10 °C in less than 8 days. Both strains also were identified as biosurfactant producers with varying emulsification activities (32−92%) and cell surface hydrophobicity (52−58%). These findings highlight the potential of both strains for restoring diesel-related substrates, particularly in Antarctica.

Exploring the potential of novel Bacillus sp. G6: Isolation, characterization, and optimization of biosurfactant production from oil-contaminated soil

Biosurfactants (BSs) are highly biodegradable, environmentally benign, and multifunctional substances having diverse industrial uses, including environment bioremediation. Because of its remarkable emulsifying properties, as well as its use in both the environment and medicine, surfactin, is considered one of the most potent BSs and belongs to the lipopeptides family. The present study was performed to isolate the potential bacteria from oil-contaminated soils. Selected bacteria were checked for biosurfactant (BS) synthesis and their characterization. Out of 32 bacteria, the most promising isolate G6 was taken for a detailed study. Based on polyphasic taxonomy it was found to belong to the novelBacillussp.Nutrient screening for higher BS synthesis usingthe Plackett-Burman design(PBD) showed thatFeSO4, NaCl andwaste engineoil have a significant influence on BS production. Further optimization utilizingBox-Behnken design(BBD) revealed that the optimized condition for higher BS synthesis wasFeSO4(2.0 %), NaCl (2.0 %), and waste engine oil (2.2 %). The highest BS yield of 3.79 ± 0.265 g/L was attained with a cell biomass of 1.51 ± 0.234 g/L with 1.92 fold increase in the yield. Based on thin-layer chromatogram (TLC),Fourier transform infrared spectroscopy(FTIR), andGas Chromatogram-Mass Spectrometry(GC–MS) studies it was observed that the probable BS was a surfactin-like molecule that is stable at a wide range of temperature (up to 100° C), pH (5–9), and salinity (3–6 %).

High-throughput evaluation of hemolytic activity through precise measurement of colony and hemolytic zone sizes of engineered Bacillus subtilis on blood agar.

Biosurfactants have remarkable characteristics, such as environmental friendliness, high safety, and excellent biodegradability. Surfactin is one of the best-known biosurfactants produced by Bacillus subtilis. Because the biosynthetic pathways of biosurfactants, such as surfactin, are complex, mutagenesis is a useful alternative to typical metabolic engineering approaches for developing high-yield strains. Therefore, there is a need for high-throughput and accurate screening methods for high-yield strains derived from mutant libraries. The blood agar lysis method, which takes advantage of the hemolytic activity of biosurfactants, is one way of determining their concentration. This method includes inoculating microbial cells onto blood-containing agar plates, and biosurfactant production is assessed based on the size of the hemolytic zone formed around each colony. Challenges with the blood agar lysis method include low experimental reproducibility and a lack of established protocols for high-throughput screening. Therefore, in this study, we investigated the effects of the inoculation procedure and media composition on the formation of hemolytic zones. We also developed a workflow to evaluate the number of colonies using robotics. The results revealed that by arranging colonies at appropriate intervals and measuring the areas of colonies and hemolytic rings using image analysis software, it was possible to accurately compare the hemolytic activity among several colonies. Although the use of the blood agar lysis method for screening is limited to surfactants exhibiting hemolytic activity, it is believed that by considering the insights gained from this study, it can contribute to the accurate screening of strains with high productivity.

A comprehensive review of biosurfactant production and its uses in the pharmaceutical industry.

Biosurfactants are naturally occurring, surface-active chemicals generated by microorganisms and have attracted interest recently because of their numerous industrial uses. Compared to their chemical equivalents, they exhibit qualities that include lower toxic levels, increased biodegradable properties, and unique physiochemical properties. Due to these traits, biosurfactants have become attractive substitutes for synthetic surfactants in the pharmaceutical industry. In-depth research has been done in the last few decades, demonstrating their vast use in various industries. This review article includes a thorough description of the various types of biosurfactants and their production processes. The production process discussed here is from oil-contaminated waste, agro-industrial waste, dairy, and sugar industry waste, and also how biosurfactants can be produced from animal fat. Various purification methods such as ultrafiltration, liquid-liquid extraction, acid precipitation, foam fraction, and adsorption are required to acquire a purified product, which is necessary in the pharmaceutical industry, are also discussed here. Alternative ways for large-scale production of biosurfactants using different statistical experimental designs such as CCD, ANN, and RSM are described here. Several uses of biosurfactants, including drug delivery systems, antibacterial and antifungal agents, wound healing, and cancer therapy, are discussed. Additionally, in this review, the future challenges and aspects of biosurfactant utilization in the pharmaceutical industry and how to overcome them are also discussed.

Determining the accuracy and suitability of common analytical techniques for sophorolipid biosurfactants.

To determine the performance of a sophorolipid biosurfactant production process, it is important to have accurate and specific analytical techniques in place. Among the most popular are the anthrone assay, gravimetric quantification (hexane:ethyl acetate extraction), and high-performance liquid chromatography (HPLC). The choice of analytical tool varies depending on cost, availability, and ease of use; however, these techniques have never been compared directly against one another. In this work, 75 fermentation broths with varying product/substrate concentrations were comprehensively tested with the 3 techniques and compared. HPLC-ultraviolet detection (198nm) was capable of quantifying C18:1 subterminal hydroxyl diacetylated lactonic sophorolipid down to a lower limit of 0.3g/L with low variability (<3.21%). Gravimetric quantification of the broths following liquid:liquid extraction with hexane and ethyl acetate showed some linearity (R2=.658) when compared to HPLC but could not quantify lower than 11.06g/L, even when no sophorolipids were detected in the sample, highlighting the non-specificity of the method to co-extract non-sophorolipid components in the final gravimetric measure. The anthrone assay showed no linearity (R2=.129) and was found to cross-react with media components (rapeseed oil, corn steep liquor, glucose), leading to consistent overestimation of sophorolipid concentration. The appearance of poor biomass separation during sample preparation with centrifugation was noted and resolved with a novel sample preparation method with pure ethanol. Extensive analysis and comparisons of the most common sophorolipid quantification techniques are explored and the limitations/advantages are highlighted. The findings provide a guide for scientists to make an informed decision on the suitable quantification tool that meets their needs, exploring all aspects of the analysis process from harvest, sample preparation, and analysis.

Screening of Microorganisms from Wastes and Identification of the Optimal Substrate for Biosurfactant Production

The production of biosurfactants from organic wastes has received significant attention due to its potential cost savings. This study involved the isolation of biosurfactant-producing microorganisms from waste sources. The surfactant properties of the 37 studied isolates were assessed by reducing surface tension and their emulsifying properties, determined by the emulsification index E24. We assessed the ability of these isolated strains to produce biosurfactants using various waste substrates, namely potato peelings, waste cooking oil and sunflower cake. Our results showed that sunflower cake exhibited better growth and biosurfactant production for most of the strains studied. This highlights that sunflower cake is a potentially effective and economical substrate for the production of biosurfactants. The most effective strains allowing to achieve an emulsification index above 50% and reduce surface tension below 40 mN m−1 were Enterobacter sp. 2pp, strain 2wfo, Peribacillus sp. 1mo, Sphingomonas sp. 2mo, Ochrobactrum sp. 5mo, Shouchella sp. 6mo, Bacillus sp. 1os, Bacillus sp. 2os. Among these strains, both previously known strains as biosurfactant producers and previously unknown strains were found. Thus, we found that among representatives of the genus Sphingomonas there are effective producers of biosurfactants. The highest yield of biosurfactant on a medium with glycerol and glucose was shown by the Bacillus sp. 2os strain of 0.501 and 0.636 g L−1, respectively.

Production and characterization of rhamnolipid biosurfactant from thermophilic Geobacillus stearothermophilus bacterium isolated from Uhud mountain.

Biosurfactants have been given considerable attention as they are potential candidates for several biotechnological applications. In this study, a promising thermophilic biosurfactant-producing HA-2 was isolated from the volcanic and arid region of Uhud mountain, Madinah, Saudi Arabia. It was identified using 16S rRNA gene sequence analysis. The biosurfactant production ability was screened using different methods such as the drop collapse test, oil spreading test, hemolytic activity test, CTAB test, and emulsification index. The ability of rhamnolipid production by the tested strain was confirmed by the polymerase chain reaction (PCR) of rhlAB. The affinity of thermophilic HA-2 to hydrophobic substrates was also investigated. Optimization of biosurfactant production was conducted. The biological activities of produced surfactant were investigated. The isolated HA-1 was identified as Geobacillus stearothermophilus strain OR911984. It could utilize waste sunflower frying oil (WSFF) oil as a low-cost carbon source. It showed high emulsification activity (52 ± 0.0%) and positive results toward other biosurfactant screening tests. The strain showed high cell adhesion to hexane with 41.2% cell surface hydrophobicity. Fourier-transform infrared (FTIR) spectra indicated the presence of hydrophobic chains that comprise lipids, sugars, and hydrophilic glycolipid components. The optimization results showed the optimal factors included potato peel as a carbon source with 68.8% emulsification activity, yeast extract as a nitrogen source with 60% emulsification activity, a pH of 9 (56.6%), and a temperature of 50° (72%). The kinetics showed that optimum biosurfactant production (572.4 mg/L) was recorded at 5 days of incubation. The produced rhamnolipid biosurfactant showed high antimicrobial activity against some human and plant pathogenic bacterial and fungal isolates and high antioxidant activity (90.4%). In addition, it enhanced wheat (Triticum aestivum) growth, with the greatest enhancement obtained with the 5% concentration. Therefore, thermophilic G. stearothermophilus is a promising rhamnolipid biosurfactant producer that utilizes many organic wastes. The produced biosurfactant could be applied as a promising emulsifier, antimicrobial, antioxidant, and plant growth promoter.

Compartive Studies and Production of Biosurfactant by Bacillus tequilensis KM15 from Marine/Salt Water /Brackish Water Species and Freshwater Fish Wastes as a Substrate

Compartive Studies and Production of Biosurfactant by Bacillus tequilensis KM15 from Marine/Salt Water /Brackish Water Species and Freshwater Fish Wastes as a Substrate

BIOSURFACTANT-MEDIATED SYNTHESIS OF GRAPHENE FLAKES FROM GRAPHITE FOR MICROBICIDAL ACTIVITY

A biologically prolific procedure involving microbes and biosurfactants as surface-active materials allows for the exfoliation of graphite into graphene flakes, harnessing microbial surface activity. In this study, the production of graphene flake has taken an unusual route with a biosurfactant as it is not the easiest method and is required in huge quantities. The biosurfactant was isolated from Pseudomonas aeruginosa. The microbe was isolated, cultured, and stored for surfactant production. The biosurfactant showed positive results for all the seven screening methods tested. The emulsification capacity was 62.7% indicating the highest stability of the biosurfactant to penetrate inside the kerosene. The production of biosurfactant in the mineral salt medium in a shaking condition provided a better result of the highest production which was then used for extraction purposes by autoclaving the culture. The exfoliation process took place once the production was over. The four main characterization techniques both spectroscopic and microscopic have revealed positive results for graphene flake production. The antimicrobial study was conducted to check the withstand capacity of the produced graphene flakes towards microbes and the results show the antimicrobial activity of the flakes. The sensitivity of graphene flakes against biotic discs was studied by antibiotic disc assay and the results show they are sensitive to the commonly administered antibiotics of today.