Production and Application of Biosurfactant Produced by Bacillus Licheniformis Ali5 in Enhanced Oil Recovery and Motor Oil Removal from Contaminated Sand

Application of biosurfactants in enhanced oil recovery ex-situ: a review

With a growing focus on environmentally friendly solutions, biosurfactants derived from plants or microorganisms have gained attention for Enhanced Oil Recovery (EOR) applications. Biosurfactants offer several advantages over existing options, including biodegradability, low toxicity, availability of raw materials, resistance to harsh reservoir conditions, and improved water/oil interfacial tension reduction. Different organisms, such as bacteria, fungi, and plants, can produce these natural surfactants. Bacillus sp. and Pseudomonas sp. bacteria are extensively studied for their ability to produce biosurfactants using low-cost carbon and nitrogen sources, exhibiting excellent surface activity and low critical micellar concentration (CMC). Fungi, though less commonly used, can also produce biosurfactants, albeit with lower interfacial activity. Plant-derived natural surfactants find wide application in laboratory tests for EOR, despite having higher CMC. This review not only summarizes the current knowledge on biosurfactants but also offers a novel comparative analysis of those produced by bacteria, fungi, and plants, examining their CMC, surface tension, and interfacial tension properties. Additionally, it quantifies the number of publications on the use of biosurfactants for Microbial Enhanced Oil Recovery ex-situ (MEOR ex-situ) over the past 30 years and compares these with biosurfactants derived from plant sources. Our study is unique in its comparative approach and the quantification of literature on MEOR ex-situ. The findings reveal that biosurfactants produced by bacteria generally exhibit superior surface activity, even at lower concentrations, compared to those produced by plants or fungi. This new comparative perspective and thorough literature analysis highlight the distinctive contributions of this study. Overall, the use of biosurfactants for EOR represents a promising approach to cleaner energy production, with the potential to reduce environmental impact while improving oil recovery.

Metabolite profiling and molecular characterization of NBAIR BSWG1: A potential strain of Bacillus subtilis against Fusarium oxysporium f. sp. udum

To address the fungal wilt of pigeon pea caused by Fusarium oxysporium f. sp. udum, farmers currently rely on chemical fungicides, despite their harmful effects. However, there is a growing need for safer alternatives like green pesticides. Bacterial biocontrol agents and their derivatives serve as potential green pesticides in the management of plant pathogens. In the present study, we aimed to identify indigenous Bacillus subtilis strains effective against F. oxysporium f. sp. udum. We used PCR and MALDI-TOF analysis to identify the active components responsible for the efficiency of efficient strain. Biochemical studies of cell-free extracts extracted from B. subtilis strains demonstrated the highest biosurfactant activity in NBAIR BSWG1, with an oil displacement of 2 cm and an emulsification index of 60 %. Molecular characterization confirmed the presence of surfactin, fengycin, and iturin coding genes in the B. subtilis strains, among them, NBAIR BSWG1 showed the highest number of lipopeptide-producing genes. Meanwhile, NBAIR BSWG1 showed inhibition of 79.84 % against F. oxysporium f. sp. udum using cell-free extract. Further metabolite profiling of NBAIR BSWG1 using MALDI-TOF analysis further confirmed surfactin, fengycin, and iturin in the purified cell-free extract of NBAIR BSWG1. Two peaks with m/z of 923.77 and 1149.92 were identified as novel lipopeptide compounds which need further characterization. The present study identified NBAIR BSWG1 as an efficient bacterial strain for the inhibition of F. oxysporium f. sp. udum and its antifungal properties are mainly due to the production of cyclic lipopeptides.

Recent progress in microbial biosurfactants production strategies: Applications, technological bottlenecks, and future outlook

Biosurfactants are surface-active compounds produced by numerous microorganisms. They have gained significant attention due to their wide applications in food, pharmaceuticals, cosmetics, agriculture, and environmental remediation. The production efficiency and yield of microbial biosurfactants have improved significantly through the development and optimization of different process parameters. This review aims to provide an in-depth analysis of recent trends and developments in microbial biosurfactant production strategies, including submerged, solid-state, and co-culture fermentation. Additionally, review discusses biosurfactants' applications, challenges, and future perspectives. It highlights their advantages over chemical surfactants, emphasizing their biodegradability, low toxicity, and diverse chemical structures. However, the critical challenges in commercializing include high production costs and low yield. Strategies like genetic engineering, process optimization, and downstream processing, have been employed to address these challenges. The review provides insights into current commercial producers and highlights future perspectives such as novel bioprocesses, efficient microbial strains, and exploring their applications in emerging industries.

Production and characterization of the lipopeptide with anti-adhesion for oral biofilm on the surface of titanium for dental implants

Titanium implants are subject to bacterial adhesion and peri-implantitis induction, and biosurfactants bring a new alternative to the fight against infections. This work aimed to produce and characterize the biosurfactant from Bacillus subtilis ATCC 19,659, its anti-adhesion and antimicrobial activity, and cell viability. Anti-adhesion studies were carried out against Streptococcus sanguinis, Staphylococcus aureus, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Proteus mirabilis as the minimum inhibitory concentration and the minimum bactericidal concentration. Cell viability was measured against osteoblast and fibroblast cells. The biosurfactant was classified as lipopeptide, with critical micelle concentration at 40 µg mL- 1, and made the titanium surface less hydrophobic. The anti-adhesion effect was observed for Staphylococcus aureus and Streptococcus sanguinis with 54% growth inhibition and presented a minimum inhibitory concentration of 15.7 µg mL- 1 for Streptococcus sanguinis and Aggregatibacter actinomycetemcomitans. The lipopeptide had no cytotoxic effect and demonstrated high potential application against bacterial biofilms.

Bioemulsifier production by Acinetobacter venetianus AMO1502: Potential for bioremediation and environmentally friendly applications

At the best conditions of the bioprocess (30 °C, pH 7.0, 3.0 g/L NaCl) were obtained 0.66 g/L cell concentration, 3.3 g/L of bioemulsifier, which showed high emulsifying activity (53 % ± 2), reducing the surface tension of the water in 47.2 % (38 mN/m). The polymeric structure of the purified bioemulsifier comprised a carbohydrate backbone composed of hexose-based amino sugars with a monomeric mass of 1099 Da, structurally similar to emulsan. A. venetianus bioemulsifier is non-phytotoxic (GI% > 80 %) against Ocimum basilicum and Brassica oleracea and non-cytotoxic (LC50 5794 mg/L) against Artemia salina, being safe local organisms in comparison to other less eco-friendly synthetic emulsifiers. This bioemulsifier effectively dispersed spilled oil in vitro (C22-C33), reducing oil mass by 12 % (w/w) and dispersing oil in a displacement area of 75 cm2 (23.8 % of the spilled area). Thus, the isolated A. venetianus AMO1502 produced a bioemulsifier potentially applicable for environmentally friendly oil spill remediation.

Enhanced production of mycelium biomass and exopolysaccharides of Pleurotus ostreatus by integrating response surface methodology and artificial neural network

This study aimed to enhance the production of mycelium biomass and exopolysaccharides (EPS) of Pleurotus ostreatus in submerged fermentation. Response Surface Methodology (RSM)sought to optimize culture conditions, whereas Artificial Neural Network (ANN)aimed to predict the mycelium biomass and EPS. After optimization of RSM model conditions, the maximum biomass (36.45 g/L) and EPS (6.72 g/L) were obtained at the optimum temperature of 22.9 °C, pH 5.6, and agitation of 138.9 rpm. Further, the Genetic Algorithm (GA) was employed to optimize the cultivation conditions in order to maximize the mycelium biomass and EPS production. The ANN model with an optimized network structure gave the coefficient of determination (R2) value of 0.99 and the least mean squared error of 1.9 for the validation set. In the end, a graphical user interface was developed to predict mycelium biomass and EPS production.

Comparative negation of amphiphile production using nutrition factors: Amyloids versus biosurfactants

Microbial amphiphiles play an important role in environmental activities such as microbial signaling, bioremediation, and biofilm formation. Microorganisms rely on their unique characteristics of interfaces to carry out critical biological functions, which are helped by amphipathic biomolecules known as amphiphiles. Bacillus amyloids aid in cell adhesion and biofilm formation. Pseudomonas sp. are essential in biofilm development and are a vital survival strategy for many bacteria. Furthermore, Pseudomonas and Bacillus are well-known for their ability to produce biosurfactants with a range of applications, including bioremediation and removing biological pollutants from different environments. The study employed 31 different media types and a range of analytical techniques to assess the presence of amyloid proteins and the absence of biosurfactants in Bacillus licheniformis K125 (GQ850525.1) and Pseudomonas fluorescens CHA0. The presence of amyloid proteins was confirmed through Congo red and thioflavin T staining. The carefully constructed medium also efficiently inhibited the synthesis of biosurfactants by these bacteria. Additionally, surface tension measurements, emulsification index, thin-layer chromatography, and high-performance thin-layer chromatography analyses indicated the absence of biosurfactants in the tested media.

Valorization of oily sludge waste using biosurfactant-producing bacteria

Oily sludge generated by the petroleum industry is not only an environmental hazard, but since it contains crude oil too, it is a valuable resource as well. This study demonstrates a methodology for the valorization of the oily sludge that allows the recovery of oil fractions by the action of microbes producing surface-active metabolites. Two bacterial isolates were used in the study that were producing different biosurfactants, identified via FTIR analysis as well as through genomic mapping of the biosurfactant pathways using RAST, ANTISMASH 7.0, STRING databases. Serratia spp. AKBS12, produced a mono-rhamnolipid, while Acinetobacter spp. AKBS16, produced emulsan. Although recovery efficiency of both biosurfactants was similar, the recovery profile with respect to the class of hydrocarbons differed. The rhamnolipid produced by Serratia spp. AKBS12 extracted mono-chained paraffins and linear alkanes, while emulsan, produced by Acinetobacter spp. AKBS16 could extract heavier paraffins. The extraction procedure is simple and involves mixing the biosurfactant with oily sludge at a temperature of 30 °C with an incubation of 9 days. Sulphuric acid precipitation releases the oil trapped in the oily sludge. The study is the first step in developing user-friendly, innovative technologies that can be linked to the concept of a circular economy.

The Extracellular Lipopeptides and Volatile Organic Compounds of Bacillus subtilis DHA41 Display Broad-Spectrum Antifungal Activity against Soil-Borne Phytopathogenic Fungi

Fusarium oxysporum f. sp. niveum (Fon) is a devastating soil-borne fungus causing Fusarium wilt in watermelon. The present study investigated the biochemical mechanism underlying the antifungal activity exhibited by the antagonistic bacterial strain DHA41, particularly against Fon. Molecular characterization based on the 16S rRNA gene confirmed that DHA41 is a strain of Bacillus subtilis, capable of synthesizing antifungal lipopeptides, such as iturins and fengycins, which was further confirmed by detecting corresponding lipopeptide biosynthesis genes, namely ItuB, ItuD, and FenD. The cell-free culture filtrate and extracellular lipopeptide extract of B. subtilis DHA41 demonstrated significant inhibitory effects on the mycelial growth of Fon, Didymella bryoniae, Sclerotinia sclerotiorum, Fusarium graminearum, and Rhizoctonia solani. The lipopeptide extract showed emulsification activity and inhibited Fon mycelial growth by 86.4% at 100 µg/mL. Transmission electron microscope observations confirmed that the lipopeptide extract disrupted Fon cellular integrity. Furthermore, B. subtilis DHA41 emitted volatile organic compounds (VOCs) that exhibited antifungal activity against Fon, D. bryoniae, S. sclerotiorum, and F. graminearum. These findings provide evidence that B. subtilis DHA41 possesses broad-spectrum antifungal activity against different fungi pathogens, including Fon, through the production of extracellular lipopeptides and VOCs.

Construct a synthetic Entner-Doudoroff pathway in Bacillus licheniformis for enhancing lichenysin production

Lichenysin, a cyclic lipopeptide biosurfactant produced by Bacillus licheniformis, is composed of aspartate, glutamine, valine, leucine, isoleucine, and branched chain fatty acids. The synthesis of these amino acids and fatty acids requires pyruvate and NADPH as the primary precursor and cofactor. Therefore, a sufficient supply of pyruvate and NADPH is crucial for lichenysin production. This study aimed to increase lichenysin production by constructing a synthetic ED pathway in B. licheniformis WX02 through introducing phosphogluconate dehydratase (encoded by gene edd) and 2-keto-3-deoxygluconate 6-phosphate aldolase (encoded by gene eda) from Escherichia coli. Additionally, the NADP⁺-dependent glucose-6-phosphate dehydrogenase (encoded by gene zwf) was overexpressed, resulting in an engineered strain WX02/pHY-edda(Ec)-zwf. Analysis of the fermentation process revealed that the concentrations of pyruvate, aspartate, glutamine, valine, leucine, branched-chain fatty acids (iC15:0, aC15:0, iC16:0, iC17:0), and NADPH in WX02/pHY-edda(Ec)-zwf were increased by 77.21%, 80.41%, 85.31%, 141.64%, 44.94%, 35.08%, 38.08%, 19.33%, 21.16%, and 425%, respectively, compared to the control strain WX02/pHY300, which resulted in a 45.43% increase of lichenysin titer. This work took advantage of the ED pathway to increase lichenysin production for the first time, and provides a promising strategy for boosting the productivity of biochemicals that require pyruvate and NADPH as precursor and cofactor.

The Potential of Bacilli-Derived Biosurfactants as an Additive for Biocontrol against Alternaria alternata Plant Pathogenic Fungi

Fungal diseases caused by Alternaria alternata constitute a significant threat to the production and quality of a wide range of crops, including beans, fruits, vegetables, and grains. Traditional methods for controlling these diseases involve synthetic chemical pesticides, which can negatively impact the environment and human health. Biosurfactants are natural, biodegradable secondary metabolites of microorganisms that have also been shown to possibly have antifungal activity against plant pathogenic fungi, including A. alternata being sustainable alternatives to synthetic pesticides. In this study, we investigated the potential of biosurfactants of three bacilli (Bacillus licheniformis DSM13, Bacillus subtilis DSM10, and Geobacillus stearothermophilus DSM2313) as a biocontrol agent against A. alternata on beans as a model organism. For this fermentation, we describe using an in-line biomass sensor monitoring both permittivity and conductivity, which are expected to correlate with cell concentration and products, respectively. After the fermentation of biosurfactants, we first characterised the properties of the biosurfactant, including their product yield, surface tension decrement capability, and emulsification index. Then, we evaluated the antifungal properties of the crude biosurfactant extracts against A. alternata, both in vitro and in vivo, by analysing various plant growth and health parameters. Our results showed that bacterial biosurfactants effectively inhibited the growth and reproduction of A. alternata in vitro and in vivo. B. licheniformis manufactured the highest amount of biosurfactant (1.37 g/L) and demonstrated the fastest growth rate, while G. stearothermophilus produced the least amount (1.28 g/L). The correlation study showed a strong positive relationship between viable cell density VCD and OD600, as well as a similarly good positive relationship between conductivity and pH. The poisoned food approach in vitro demonstrated that all three strains suppressed mycelial development by 70–80% when applied with the highest tested dosage of 30%. Regarding in vivo investigations, B. subtilis post-infection treatment decreased the disease severity to 30%, whereas B. licheniformis and G. stearothermophilus post-infection treatment reduced disease severity by 25% and 5%, respectively. The study also revealed that the plant’s total height, root length, and stem length were unaffected by the treatment or the infection.

Optimization of Medium Components for Fed-Batch Fermentation Using Central Composite Design to Enhance Lichenysin Production by Bacillus licheniformis Ali5

Lichenysin, an amphiphilic biosurfactant with structural and physicochemical properties similar to surfactin, is produced by Bacillus licheniformis. Its low toxicity, good environmental compatibility, solubilization, foaming, emulsification and detergent activities have led to a wide range of applications in agricultural biocontrol, enhanced oil recovery, foaming agents for cosmetics and detergents for household cleaning products. However, despite the extraordinary surface-active properties and potential applications of lichenysin, the number of wild bacteria found so far is relatively low. Low titers and high costs are the main limiting factors for widespread industrial applications. In this study, a factorial design was used to optimize the composition of the medium for the production of lichenysin by Bacillus licheniformis Ali5. Firstly, the solutions of carbon, nitrogen, amino acids, inorganic salts and trace elements in the medium were evaluated in flasks using a single-factor optimization method. Meanwhile, the operating conditions were optimized in the same way. Afterwards, a partial factorial design was used to investigate the effect of six variables (five medium compositions and inoculum size) on lichenysin production. Based on the results obtained, the concentrations of sucrose and ammonium nitrate and the inoculum size were considered to be important for lichenysin production. Subsequently, a full factorial design was used to optimize these three variables. The optimized medium composition were sucrose 19.8 g/L, NH4NO3 3.9 g/L, K2HPO4·3H2O 4.0 g/L, MgSO4·7H2O 0.6 g/L, FeSO4·7H2O 0.1 g/L, CaCl2 0.01 g/L, NaCl 3.0, trace elements 1.2 mL/L. Finally, the titer of lichenysin after fed-batch fermentation reached 1425.85 mg/L, which was approximately 5.5 times higher than the titer of lichenysin from the original medium. Consequently, the method was further demonstrated to be suitable for lichenysin production.

Hydrocarbon Degradation and Microbial Survival Improvement in Response to γ-Polyglutamic Acid Application

To improve the environmental sustainability of cleanup activities of contaminated sites there is a need to develop technologies that minimize soil and habitat disturbances. Cleanup technologies, such as bioremediation, are based on biological products and processes, and they are important for the future of our planet. We studied the potential of γ-poly glutamic acid (PGA) as a natural component of biofilm produced by Bacillus sp. to be used for the decomposition of petroleum products, such as heavy naphtha (N), lubricating oil (O), and grease (G). The study aimed to assess the impact of the use of different concentrations of PGA on the degradation process of various fractions of petroleum hydrocarbons (PH) and its effect on bacterial population growth in harsh conditions of PH contamination. In laboratory conditions, four treatments of PGA with each of the petroleum products (N, O, and G) were tested: PGA₀ (reference), PGA₁ (1% PGA), PGA_1B (1% PGA with Bacillus licheniformis), and PGA₁₀ (10% PGA). After 7, 28, 56, and 112 days of the experiment, the percentage yield extraction, hydrocarbon mass loss, geochemical ratios, pH, electrical conductivity, and microorganisms survival were determined. We observed an increase in PH removal, reflected as a higher amount of extraction yield (growing with time and reaching about 11% in G) and loss of hydrocarbon mass (about 4% in O and G) in all treatments of the PGA compared to the reference. The positive degradation impact was intensive until around day 60. The PH removal stimulation by PGA was also reflected by changes in the values of geochemical ratios, which indicated that the highest rate of degradation was at the initial stage of the process. In general, for the stimulation of PH removal, using a lower (1%) concentration of PGA resulted in better performance than a higher concentration (10%). The PH removal facilitated by PGA is related to the anionic homopoliamid structure of the molecule and its action as a surfactant, which leads to the formation of micelles and the gradual release of PH absorbed in the zeolite carrier. Moreover, the protective properties of PGA against the extinction of bacteria under high concentrations of PH were identified. Generally, the γ-PGA biopolymer helps to degrade the hydrocarbon pollutants and stabilize the environment suitable for microbial degraders development.

Nitrogen dependence of rhamnolipid mediated degradation of petroleum crude oil by indigenous Pseudomonas sp. WD23 in seawater

Effect of oil spills on living forms demands for safe, ecofriendly and cost-effective methods to repair the damage. Pseudomonads have exceptional tolerance to xenobiotics and can grow at varied environmental conditions. This study aims at biosurfactant mediated degradation of petroleum crude oil by an indigenous Pseudomonas sp. WD23 in sea water. Pseudomonas sp. WD23 degraded 34% of petroleum crude oil (1.0% v/v) on supplementation of yeast extract (0.05 g/L) with glucose (1.0 g/L) in seawater. The strain produced a biosurfactant which was confirmed as a rhamnolipid (lipid: rhamnose 1:3.35) by FT-IR, LCMS and quantitative analysis. Produced rhamnolipid had low CMC (20.0 mg/L), emulsified petroleum oils (75-80%) and had high tolreance to varied conditions of pH, temperature and ionic strength. OFAT studies were performed to analyse the effect of petroleum crude oil, glucose, inoculum, yeast extract, pH, agitation speed and incubation time on degradation by Pseudomonas sp. WD23. Petroleum crude oil and glucose had significant effect on biodegradation, rhamnolipid production and growth, further optimized by central composite design. At optimum conditions of 3.414% v/v PCO and 6.53 g/L glucose, maximum degradation of 81.8 ± 0.67% was observed at pH 7.5, 100 RPM, 15.0% v/v inoculum in 28 days, with a 3-fold increase in biodegradation. GCMS analysis revealed degradation (86-100%) of all low and high molecular weight hydrocarbons present in petroleum crude oil. Hence, the strain Pseudomonas sp. WD23 can be effectively developed for management of oil spills in seas and oceans due to its excellent degradation abilities.

Bacillus licheniformis: The unexplored alternative for the anaerobic production of lipopeptide biosurfactants?

Microbial biosurfactants have attracted the attention of researchers and companies for the last decades, as they are considered promising candidates to replace chemical surfactants in numerous applications. Although in the last years, considerable advances were performed regarding strain engineering and the use of low-cost substrates in order to reduce their production costs, one of the main bottlenecks is their production at industrial scale. Conventional aerobic biosurfactant production processes result in excessive foaming, due to the use of high agitation and aeration rates necessary to increase dissolved oxygen concentration to allow microbial growth and biosurfactant production. Different approaches have been studied to overcome this problem, although with limited success. A not widely explored alternative is the development of foam-free processes through the anaerobic growth of biosurfactant-producing microorganisms. Surfactin, produced by Bacillus subtilis, is the most widely studied lipopeptide biosurfactant, and the most powerful biosurfactant known so far. Bacillus licheniformis strains produce lichenysin, a lipopeptide biosurfactant which structure is similar to surfactin. However, despite its extraordinary surface-active properties and potential applications, lichenysin has been scarcely studied. According to previous studies, B. licheniformis is better adapted to anaerobic growth than B. subtilis, and could be a good alternative for the anaerobic production of lipopeptide biosurfactants. In this review, the potential and limitations of surfactin and lichenysin production under anaerobic conditions will be analyzed, and the possibility of implementing foam-free processes for lichenysin production, in order to expand the market and applications of biosurfactants in different fields, will be discussed.

Characterization of a potent biosurfactant produced from Franconibacter sp. IITDAS19 and its application in enhanced oil recovery

Biosurfactants are surface-active molecules produced from microorganisms either on the cell surface or secreted extracellularly. Several biosurfactant producing microorganisms have been isolated to date, but they differ in their efficacy towards different types of hydrocarbons. Here, we report the isolation and characterization of a biosurfactant producing bacterium Franconibacter sp. IITDAS19 from crude oil contaminated soil. The biosurfactant was isolated, purified and characterized. It was identified as a glycolipid. It was found to be very stable at wide range of temperatures, pH and salt concentrations. It could reduce the surface tension of the water from 71 mN/m to 31 mN/m. IITDAS19 showed very high efficacy towards both aliphatic and aromatic hydrocarbons. It resulted in about 63% recovery of residual oil in a sand pack column. Our results suggested that the produced biosurfactant can be used for enhanced oil recovery. To our knowledge, this is the first report demonstrating the detailed characterization of a biosurfactant from Franconibacter spp.

Lipopeptide Biosurfactants from Bacillus spp.: Types, Production, Biological Activities, and Applications in Food

Biosurfactants are a functionally and structurally heterogeneous group of biomolecules produced by multiple filamentous fungi, yeast, and bacteria, and characterized by their distinct surface and emulsifying ability. The genus Bacillus is well studied for biosurfactant production as it produces various types of lipopeptides, for example, lichenysins, bacillomycin, fengycins, and surfactins. Bacillus lipopeptides possess a broad spectrum of biological activities such as antimicrobial, antitumor, immunosuppressant, and antidiabetic, in addition to their use in skincare. Moreover, Bacillus lipopeptides are also involved in various food products to increase the antimicrobial, surfactant, and emulsification impact. From the previously published articles, it can be concluded that biosurfactants have strong potential to be used in food, healthcare, and agriculture. In this review article, we discuss the versatile functions of lipopeptide Bacillus species with particular emphasis on the biological activities and their applications in food.

Structural and functional characterization of a novel biosurfactant from Bacillus sp. IITD106

Plant saponins are attractive biosurfactants and have been used to enhance phytoremediation. There are only limited reports on saponins produced by bacteria. Here, we report structural and functional characterization of a novel saponin produced by Bacillus sp. IITD106. Biosurfactant production was determined by emulsion index, drop collapse, oil displacement and hemolytic assays. The biosurfactant was stable over a range of temperature (30 °C to 70 °C), salinity (0-150 g liter^-1) and pH (4-10). The surface tension of the medium reduced from 58.89 mN/m to 27.29 mN/m using the isolated biosurfactant. Chromatographic analysis revealed the biosurfactant to be a glycolipid. LCMS, FT-IR and NMR analysis identified the biosurfactant to be a saponin containing two sugar groups and a 5 ringed triterpene sapogenin unit. Genome sequencing of the strain revealed the presence of genes responsible for biosynthesis of saponin. Statistical optimization of culture medium resulted in 9.3-fold increase in biosurfactant production. Kinetics study of biosurfactant production performed in a stirred tank batch bioreactor resulted in 6.04 g liter^-1 and 6.9 g liter^-1 biomass and biosurfactant concentration, respectively. The biosurfactant was found to solubilize polycyclic aromatic hydrocarbons. The potential of cell free biosurfactant containing broth to enhance oil recovery was tested in a sand pack column and recovery of 63% of residual oil was observed. To our knowledge this is the first report of saponin production by any of the strains of Bacillus.

Biosurfactants: Potential Agents for Controlling Cellular Communication, Motility, and Antagonism

Biosurfactants are surface-active molecules produced by microorganisms, either on the cell surface or secreted extracellularly. They form a thin film on the surface of microorganisms and help in their detachment or attachment to other cell surfaces. They are involved in regulating the motility of bacteria and quorum sensing. Here, we describe the various types of biosurfactants produced by microorganisms and their role in controlling motility, antagonism, virulence, and cellular communication.

Enhanced Activity by Genetic Complementarity: Heterologous Secretion of Clostridial Cellulases by Bacillus licheniformis and Bacillus velezensis

To adapt to various ecological niches, the members of genus Bacillus display a wide spectrum of glycoside hydrolases (GH) responsible for the hydrolysis of cellulose and lignocellulose. Being abundant and renewable, cellulose-containing plant biomass may be applied as a substrate in second-generation biotechnologies for the production of platform chemicals. The present study aims to enhance the natural cellulase activity of two promising 2,3-butanediol (2,3-BD) producers, Bacillus licheniformis 24 and B. velezensis 5RB, by cloning and heterologous expression of cel8A and cel48S genes of Acetivibrio thermocellus. In B. licheniformis, the endocellulase Cel8A (GH8) was cloned to supplement the action of CelA (GH9), while in B. velezensis, the cellobiohydrolase Cel48S (GH48) successfully complemented the activity of endo-cellulase EglS (GH5). The expression of the natural and heterologous cellulase genes in both hosts was demonstrated by reverse-transcription PCR. The secretion of clostridial cellulases was additionally enhanced by enzyme fusion to the subtilisin-like signal peptide, reaching a significant increase in the cellulase activity of the cell-free supernatants. The results presented are the first to reveal the possibility of genetic complementation for enhancement of cellulase activity in bacilli, thus opening the prospect for genetic improvement of strains with an important biotechnological application.

Exploiting Microbes in the Petroleum Field: Analyzing the Credibility of Microbial Enhanced Oil Recovery (MEOR)

Crude oil is a major energy source that is exploited globally to achieve economic growth. To meet the growing demands for oil, in an environment of stringent environmental regulations and economic and technical pressure, industries have been required to develop novel oil salvaging techniques. The remaining ~70% of the world’s conventional oil (one-third of the available total petroleum) is trapped in depleted and marginal reservoirs, and could thus be potentially recovered and used. The only means of extracting this oil is via microbial enhanced oil recovery (MEOR). This tertiary oil recovery method employs indigenous microorganisms and their metabolic products to enhance oil mobilization. Although a significant amount of research has been undertaken on MEOR, the absence of convincing evidence has contributed to the petroleum industry’s low interest, as evidenced by the issuance of 400+ patents on MEOR that have not been accepted by this sector. The majority of the world’s MEOR field trials are briefly described in this review. However, the presented research fails to provide valid verification that the microbial system has the potential to address the identified constraints. Rather than promising certainty, MEOR will persist as an unverified concept unless further research and investigations are carried out.

Sustainable Surfactin Production by Bacillus subtilis Using Crude Glycerol from Different Wastes

Most biosurfactants are obtained using costly culture media and purification processes, which limits their wider industrial use. Sustainability of their production processes can be achieved, in part, by using cheap substrates found among agricultural and food wastes or byproducts. In the present study, crude glycerol, a raw material obtained from several industrial processes, was evaluated as a potential low-cost carbon source to reduce the costs of surfactin production by Bacillus subtilis #309. The culture medium containing soap-derived waste glycerol led to the best surfactin production, reaching about 2.8 g/L. To the best of our knowledge, this is the first report describing surfactin production by B. subtilis using stearin and soap wastes as carbon sources. A complete chemical characterization of surfactin analogs produced from the different waste glycerol samples was performed by liquid chromatography-mass spectrometry (LC-MS) and Fourier transform infrared spectroscopy (FTIR). Furthermore, the surfactin produced in the study exhibited good stability in a wide range of pH, salinity and temperatures, suggesting its potential for several applications in biotechnology.

Biosurfactant based formulation of Pseudomonas guariconensis LE3 with multifarious plant growth promoting traits controls charcoal rot disease in Helianthus annus

Biosurfactants are environment compatible surface-active biomolecules with multifunctional properties which can be utilized in various industries. In this study a biosurfactant producing novel plant growth promoting isolate Pseudomonas guariconensis LE3 from the rhizosphere of Lycopersicon esculentum is presented as biostimulant and biocontrol agent. Biosurfactant extracted from culture was characterized to be mixture of various mono- and di-rhamnolipids with antagonistic activity against Macrophomina phaseolina, causal agent of charcoal rot in diverse crops. Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (¹H NMR) analysis confirmed the rhamnolipid nature of biosurfactant. PCR analysis established the presence of genes involved in synthesis of antibiotics diacetylphloroglucinol, phenazine 1-carboxylic acid and pyocyanin, and lytic enzymes chitinase and endoglucanase suggesting biocontrol potential of the isolate. Plant growth promoting activities shown by LE3 were phosphate solubilization and production of siderophores, indole acetic acid (IAA), ammonia and 1-aminocyclopropane-1-carboxylate deaminase (ACCD). To assemble all the characteristics of LE3 various bioformuations were developed. Amendment of biosurfactant in bioformulation of LE3 cells improved the shelf life. Biosurfactant amended formulation of LE3 cells was most effective in biocontrol of charcoal rot disease of sunflower and growth promotion in field conditions. The root adhered soil mass of plantlets inoculated with LE3 plus biosurfactant was significantly higher over control. Biosurfactant amended formulation of LE3 cells caused maximum yield enhancement (80.80%) and biocontrol activity (75.45%), indicating that addition of biosurfactant improves the plant-bacterial interaction and soil properties leading to better control of disease and overall improvement of plant health and yield.

Biotechnological applications of Bacillus licheniformis

Bacillus licheniformis is a Gram positive spore-forming bacterial species of high biotechnological interest with numerous present and potential uses, including the production of bioactive compounds that are applied in a wide range of fields, such as aquaculture, agriculture, food, biomedicine, and pharmaceutical industries. Its use as an expression vector for the production of enzymes and other bioproducts is also gaining interest due to the availability of novel genetic manipulation tools. Furthermore, besides its widespread use as a probiotic, other biotechnological applications of B. licheniformis strains include: bioflocculation, biomineralization, biofuel production, bioremediation, and anti-biofilm activity. Although authorities have approved the use of B. licheniformis as a feed additive worldwide due to the absence of toxigenic potential, some probiotics containing this bacterium are considered unsafe due to the possible transference of antibiotic resistance genes. The wide variability in biological activities and genetic characteristics of this species makes it necessary to establish an exact protocol for describing the novel strains, in order to evaluate its biotechnological potential.

Novel Bioformulations Developed from Pseudomonas putida BSP9 and its Biosurfactant for Growth Promotion of Brassica juncea (L.)

In this study, Pseudomonas putida BSP9 isolated from rhizosphere of Brassica juncea was investigated for its plant growth promoting and biosurfactant producing activities. The isolate showed the ability to produce indole acetic acid, siderophore, phosphate solubilization activity and was an efficient producer of biosurfactant. Purification (of the biosurfactant) by thin layer chromatography (TLC) and further characterization by Fourier transform infrared spectroscopy (FTIR) revealed that biosurfactant produced by the isolate belonged to the glycolipid category, which is largely produced by Pseudomonas sp. In addition, liquid chromatography-mass spectroscopy (LC-MS) analysis showed the presence of a mixture of six mono-rhamnolipidic and a di-rhamnolipidic congeners, confirming it as a rhamnolipid biosurfactant. Bioformulations were developed using BSP9 and its biosurfactant to check their impact on promoting plant growth in B. juncea. It was noted from the study that bioformulations amended with biosurfactant (singly or in combination with BSP9) resulted in enhancement in the growth parameters of B. juncea as compared to untreated control. Maximum increment was achieved by plants inoculated with bioformulation that had BSP9 plus biosurfactant. The study also suggested that growth promotion was significant up to a threshold level of biosurfactant and that further increasing the concentration did not further enhance the growth parameter values of the plant. The study proves that novel bioformulations can be developed by integrating plant growth promoting rhizobacteria (PGPR) and their biosurfactant, and they can be effectively used for increasing agricultural productivity while minimizing our dependence on agrochemicals.

Statistical and Artificial Neural Network Approaches to Modeling and Optimization of Fermentation Conditions for Production of a Surface/Bioactive Glyco-lipo-peptide

A freshwater alkaliphilic strain of Pseudomonas aeruginosa, grown on waste frying oil-basal medium, produced a surface-active metabolite identified as glycolipopeptide. Bioprocess conditions namely temperature, pH, agitation and duration were comparatively modeled using statistical and artificial neural network (ANN) methods to predict and optimize product yield using the matrix of a central composite rotatable design (CCRD). Response surface methodology (RSM) was the statistical approach while a feed-forward neural network, trained with Levenberg–Marquardt back-propagation algorithm, was the neural network method. Glycolipopeptide model was predicted by a significant (P < 0.001, R² of 0.9923) quadratic function of the RSM with a mean squared error (MSE) of 3.6661. The neural network model, on the other hand, returned an R² value of 0.9964 with an MSE of 1.7844. From all error metrics considered, ANN glycolipopeptide model significantly (P < 0.01) outperformed RSM counterpart in predictive modeling capability. Optimization of factor levels for maximum glycolipopeptide concentration produced bioprocess conditions of 32 °C for temperature, 7.6 for pH, agitation speed of 130 rpm and a fermentation time of 66 h, at a combined desirability function of 0.872. The glycosylated lipid-tailed peptide demonstrated significant anti-bacterial activity (MIC = 8.125 µg/mL) against Proteus vulgaris, dose-dependent anti-biofilm activities against Escherichia coli (83%) and Candida dubliniensis (90%) in 24 h and an equally dose-dependent cytotoxic activity against human breast (MCF-7: IC50 = 65.12 µg/mL) and cervical (HeLa: IC50 = 16.44 µg/mL) cancer cell lines. The glycolipopeptide compound is recommended for further studies and trials for application in human cancer therapy.