Biosurfactant Production Research Articles

Surfactants produced from carbohydrate derivatives: Part 2. A review on the value chain, synthesis, and the potential role of artificial intelligence within the biorefinery concept

AbstractThis comprehensive and critical review explores the synthesis and applications of carbohydrate‐based surfactants within the biorefinery concept, focusing on biobased sugar‐head molecules suitable for use across several manufacturing sectors, including cosmetics, pharmaceuticals, household products, detergents, and foods. The main focus relies on sustainable alternatives to conventional surfactants, which could reduce the final manufacturing carbon footprint of several industrial feedstocks and products. A thorough analysis of raw materials, highlighting the significance of feedstock sources, and the current biobased surfactants and rhamnolipid biosurfactants production trends, is presented. Key organic reactions for the production of sorbitan esters, sucrose esters, alkyl polyglycosides, and fatty acid glucamines, such as glycosidation, acylation, and etherification, as well as the production of rhamnolipids through fermentation are described. Given the scarce literature on the characterization of these surfactant types within the hydrophilic–lipophilic deviation (HLD) framework, the surfactant contribution parameter (SCP) in the HLD equation for sugar‐head surfactants is critically assessed. The economic landscape is also discussed, noting the significant growth in the biobased surfactants and biosurfactant market, driven by environmental awareness and regulatory changes, with projections indicating a substantial market increase in the forthcoming years. Finally, the promising potential of generative artificial intelligence (AI) in developing customized surfactant molecules, with optimized properties for targeted applications, is emphasized as a promising avenue for future research.

Investigating the mechanism of interfacial tension reduction through the combination of low-salinity water and bacteria

In the enhanced oil recovery (EOR) process, interfacial tension (IFT) has become a crucial factor because of its impact on the recovery of residual oil. The use of surfactants and biosurfactants can reduce IFT and enhance oil recovery by decreasing it. Asphaltene in crude oil has the structural ability to act as a surface-active material. In microbial-enhanced oil recovery (MEOR), biosurfactant production, even in small amounts, is a significant mechanism that reduces IFT. This study aimed to investigate fluid/fluid interaction by combining low biosurfactant values and low-salinity water using NaCl, MgCl2, and CaCl2 salts at concentrations of 0, 1000, and 5000 ppm, along with Geobacillus stearothermophilus. By evaluating the IFT, this study investigated different percentages of 0, 1, and 5 wt.% of varying asphaltene with aqueous bulk containing low-salinity water and its combination with bacteria. The results indicated G. Stearothermophilus led to the formation of biosurfactants, resulting in a reduction in IFT for both acidic and basic asphaltene. Moreover, the interaction between asphaltene and G. Stearothermophilus with higher asphaltene percentages showed a decrease in IFT under both acidic and basic conditions. Additionally, the study found that the interaction between acidic asphaltene and G. stearothermophilus, in the presence of CaCl2, NaCl, and MgCl2 salts, resulted in a higher formation of biosurfactants and intrinsic surfactants at the interface of the two phases, in contrast to the interaction involving basic asphaltene. These findings emphasize the dependence of the interactions between asphaltene and G. Stearothermophilus, salt, and bacteria on the specific type and concentration of asphaltene.

Optimized Feeding Strategies for Biosurfactant Production from Acetate by Alcanivorax borkumensis SK2

Biosurfactants are much-discussed alternatives to petro- and oleochemical surfactants. Alcanivorax borkumensis, a marine, Gram-negative γ-proteobacterium, produces a glycine-glucolipid biosurfactant from hydrocarbons, pyruvate, and acetate as carbon sources. Sustainable acetate production from lignocellulose or syngas adds to its relevance for the bioeconomy. This study investigated nitrogen sources and carbon-to-nitrogen ratios (C/N) to optimize fed-batch fermentation for biosurfactant production using A. borkumensis with acetate as the carbon source. Urea enabled high biosurfactant production, which was confirmed in DO-based fed-batch fermentation. Varying C/N ratios led to increased glycine-glucolipid production and decreased biomass production, with improvement plateauing at a C/N ratio of 26.7 Cmol Nmol−1. pH-stat fed-batch fermentation using glacial acetic acid as the carbon source and a pH-adjusting agent doubled the biosurfactant production. Finally, bubble-free membrane aeration was used to prevent extensive foam formation observed during conventional bubble aeration. The efficient production made it possible to investigate the bioactivity of glycine-glucolipid in combination with antibiotics against various microorganisms. Our findings allow for the leverage of glycine-glucolipid biosurfactant production using acetate as a carbon source.

Three strategy rules of filamentous fungi in hydrocarbon remediation: an overview.

Remediation of hydrocarbon contaminations requires much attention nowadays since it causes detrimental effects on land and even worse impacts on aquatic environments. Tools of bioremediation especially filamentous fungi permissible for cleaning up as much as conceivable, at least they turn into non-toxic residues with less consumed periods. Inorganic chemicals, CO2, H2O, and cell biomass are produced as a result of the breakdown and mineralization of petroleum hydrocarbon pollutants. This paper presents a detailed overview of three strategic rules of filamentous fungi in remediating the various aliphatic, and aromatic hydrocarbon compounds: utilizing carbons from hydrocarbons as sole energy, Co-metabolism manners (Enzymatic and Non-enzymatic theories), and Biosorption approaches. Upliftment in the degradation rate of complex hydrocarbon by the Filamentous Fungi in consortia scenario we can say, "Fungal Talk", which includes a variety of cellular mechanisms, including biosurfactant production, biomineralization, and precipitation, etc., This review not only displays its efficiency but showcases the field applications - cost-effective, reliable, eco-friendly, easy to culture as biomass, applicable in both land and any water bodies in operational environment cleanups. Nevertheless, the potentiality of fungi-human interaction has not been fully understood, henceforth further studies are highly endorsed with spore pathogenicity of the fungal species capable of high remediation rate, and the gene knockout study, if the specific peptides cause toxicity to any living matters via Genomics and Proteomics approaches, before application of any in situ or ex situ environments.

Valorization and kinetic modeling of biosurfactant produced by Kocuria marina DAGII using waste cooking oil as a substrate

Microbial biosurfactant has wide applications in industrial sectors owing to their eco-friendly and biocompatible nature giving, an alternative to chemically synthesized surfactants. In our study, Kocuria marina DAG II, an isolated bacterium was observed to produce a biosurfactant. The production of biosurfactant was established by oil-spreading (3.72 ± 0.15 cm), drop collapse, and CTAB (Cetyltrimethyl ammonium bromide) assay. Biosurfactant activity was re-confirmed by the reduction in surface tension of uninoculated broth from 68.52 mN/m to 47.40 ± 0.57 mN/m. Chemical characterization study of the biosurfactant was done by TLC (thin-layer chromatography) indicating the presence of proteins (Rf = 0.78 ± 0.08), lipids (Rf = 0.79 ± 0.09), and polysaccharides (Rf = 0.81 ± 0.06). FTIR and NMR (1HNMR and 13CNMR) studies confirmed the presence of different functional groups and revalidated the presence of amino acids, lipids, and polysaccharides in the biosurfactant. From the optimization study, the highest production of biosurfactant having a yield of 3.05 ± 0.05 g/L was obtained at a temperature of 31 °C and pH 8, when kept for an incubation period of 88 hr. The addition of rancid and waste-frying mustard oil and used engine oil could enhance the production of biosurfactant by Kocuria marinaDAGII hence substantiating the concept of value-added biosurfactant production from waste. Kinetic modeling showed a good fit between experimental and predicted values using modified Gompertz model with R2 values of 0.99 and 0.99. The biosurfactant exhibited radical scavenging activity through DPPHand ABTS assays with IC50 values of 1.29 mg/ml and 0.56 mg/ml respectively. The biosurfactant produced by Kocuria marina DAG II could be utilized for various applications, bypassing the need for a synthetic surfactant.

Heavy metal application of response surface optimized-lipopeptide biosurfactant produced by Pseudomonas aeruginosa strain CGA-02 in low-cost substrate

Cost-effective methods of biosurfactant production with minimal environmental impact are needed as global demand continues to increase. This study evaluated lipopeptide biosurfactant production in a Pseudomonas aeruginosa strain CGA-02 using a low-cost carbon substrate. The structural properties of the biosurfactant and applicability of the biosurfactant in heavy metal removal were evaluated. Response surface methodology (RSM) involving central composite design (CCD) was used to optimize process parameters to maximize biosurfactant production. The study identified sugar cane molasses and sodium nitrate as carbon and nitrogen sources of choice for bacterial growth and biosurfactant production, with a relatively 2.64-fold increase in biosurfactant yield under optimized conditions. Analysis of the biosurfactant measured a surface tension reduction of water from 72.2 ± 0.26 to 30.5 ± 0.2 mN/m at 40 mg/L critical micelle concentration. GC–MS and FTIR analysis revealed structural properties of the lipopeptide biosurfactant, with fatty acid components predominantly 9-octadecenoic acid (oleic acid), n-hexadecanoic acid, cyclotetrasiloxane and trimyristin, and infrared peaks belonging to amine, carboxyl, nitrile, alkanol, ether and carbonyl groups. Capture of heavy metals using the biosurfactant was evaluated in soil microcosms. Removal rates of 80.47, 100, 77.57, 100, and 97.57% were recorded for As, Pb, Hg, Cd and Cr respectively after 12 weeks of incubation. There was no significant difference (p < 0.05) in the removal efficiency of the biosurfactant and an analogous chemical surfactant, sodium dodecyl sulphate. First and second-order kinetic models described heavy metal removal rates by the biosurfactant. We demonstrate the production of a useful biosurfactant using low-cost waste carbon.

Production, characterization, and application of Pseudoxanthomonas taiwanensis biosurfactant: a green chemical for microbial enhanced oil recovery (MEOR)

Biosurfactants, as microbial bioproducts, have significant potential in the field of microbial enhanced oil recovery (MEOR). Biosurfactants are microbial bioproducts with the potential to reduce the interfacial tension (IFT) between crude oil and water, thus enhancing oil recovery. This study aims to investigate the production and characterization of biosurfactants and evaluate their effectiveness in increasing oil recovery. Pseudoxanthomonas taiwanensis was cultured on SMSS medium to produce biosurfactants. Crude oil was found to be the most effective carbon source for biosurfactant production. The biosurfactants exhibited comparable activity to sodium dodecyl sulfate (SDS) at a concentration of 400 ppm in reducing IFT. It was characterized as glycolipids, showing stability in emulsions at high temperatures (up to 120 °C), pH levels ranging from 3 to 9, and NaCl concentrations up to 10% (w/v). Response surface methodology revealed the optimized conditions for the most stable biosurfactants (pH 7, temperature of 40 °C, and salinity of 2%), resulting in an EI24 value of 64.45%. Experimental evaluations included sand pack column and core flooding studies, which demonstrated additional oil recovery of 36.04% and 12.92%, respectively. These results indicate the potential application of P. taiwanensis biosurfactants as sustainable and environmentally friendly approaches to enhance oil recovery in MEOR processes.

Biosurfactant production potentials of microorganisms isolated from atmosphere of five petroleum stations at Tanke, Ilorin, Kwara State, Nigeria

Biosurfactants aid in bioremediation by improving the bioavailability of hydrocarbon contaminants. The objective of this work was to isolate, enumerate and identify bacteria and fungi for their biosurfactant production potential in the atmosphere of five petroleum stations at Tanke, Ilorin, Kwara State, Nigeria using appropriate, standard microbiological methods (haemolysis test, emulsification index test, drop collapse test and oil displacement test). Fourteen bacteria and ten fungi were isolated in this study. The bacterial isolates belong to the genus Bacillus, Corynebacterium, Micrococcus, Staphylococcus, Listeria, Clostridium. The fungal isolates are of the genus Neurospora, Curvularia, Aspergillus, Fusarium, Rhizopus, Cladosporium, Colletotrichum, Sclerotinia. The mean number of bacteria counted during the sampling ranged from 3.48±1.15*102 CFU to 4.82 ±1.69*102 CFU, with petrol station 4 having the highest bacteria count (2.41*102 CFU) and petrol station 3 having the lowest bacteria count (1.74*102 CFU). The mean fungal count ranged from 7±3.7 CFU to 8.6±4.7 *102 CFU, with petrol station 4 having the highest fungal count (4.3 *10 CFU) and petrol station 3 having the lowest fungal count (3.4*10 CFU). Bacillus species showed promise of biosurfactant production after screening. Aspergillus fumigatus was the most prevalent fungus isolated (24%) while Staphylococcus epidermidis was the most prevalent bacterium isolated (11%). Some of these organisms are known opportunistic pathogens therefore, improved ventilation and sanitation of the petrol stations should be carried out to reduce the microbial load in the air. Also, bacteria that produce biosurfactant can be isolated from air of gas stations.

Understanding Pathways, Substrates, and Media Optimization to Maximize Microbial Biosurfactant Production

Abstract: The production of amphiphilic chemicals, known as biosurfactants, by different microorganisms is essential for lowering interfacial and surface tension. The pathways of biosurfactant synthesis are examined in this review, with a focus on the influence of carbon substrates on biosynthesis. It also covers the variety of substrates used in the production of biosurfactants, such as lignocellulosic wastes, agro-industrial wastes, oil processing byproducts, starch-rich wastes, industrial wastes derived from plants and animals, fish and chicken wastes, fruit and vegetable wastes, and wastes from fish and poultry operations. In addition, the optimization of media for the formation of biosurfactants is discussed, with particular attention to temperature, pH, concentration of salt, and sources of carbon and nitrogen. It is crucial to comprehend these routes and optimization techniques in order to address the economic and environmental issues related to waste management and increase the efficiency of biosurfactant production.

Study of petrol degrading bacteria and screening for biosurfactants

Petroleum-based products when mixed with soil, air and water can lead to environmental pollution which can be dangerous for humans. In the current study, soil samples from the petrol unloading area of a petrol pump were collected and nine isolates of petrol degrading bacteria were isolated from the soil by enrichment technique using Bushnell and Hass media. The isolated bacteria could degrade up to 5% petrol and the best degraders were chosen after evaluating their cell mass when grown in the presence of petrol. The percentage of petrol degraded after different intervals of incubation was compared using a UV-vis double beam spectrometer at 228 nm. It was found that the two bacteria - Pseudomonas aeruginosa and Burkholderia cepacia degraded petrol 94.96% and 94.74%, respectively, by day 15 of incubation. The percentage degradation gradually decreased by day 20. Both bacteria were also screened for the production of biosurfactants through haemolysis. It was found that both the bacteria could produce biosurfactant along with them being a potent petrol degrader.

A mini-review on biosurfactants from natural-based resources: Sources, production, and application in oil industries

Increasing energy demand and depletion of producing wells around the globe necessitate oil industries to seek alternative mechanisms to increase oil production. Among various chemical enhanced oil recovery (CEOR) unveiled today, surfactants have become indispensable chemical agents in oil industries because of their wide applications in both onshore and offshore operational activities. Unfortunately, considerable numbers of these surfactants are synthetic causing treatment and disposal of effluents uneconomical to oil industries. This arises due to strong legislation laws enforced by governing bodies to ensure cleaner and safer environments. Consequently, the search for biodegradable surfactants from natural-based resources has revolved around the oil industries aimed at reducing the impacts of synthetic products both environmentally and economically. Plants are widely recognised as natural resources to obtain biosurfactants from their naturally producing saponins. In addition, other chemical compounds derived directly from plant parts are converted to biosurfactants commonly referred to as green biosurfactants. However, researchers have expressed reservations about sustainable biosurfactant production from plants due to limited access to plant resources. The present review discusses the types, properties, sources, synthesis, and applications of biosurfactants in EOR. Furthermore, the paper presents prospects of biosurfactants in EOR and proposes a sustainable production mechanism.

Sustainable production of sophorolipid biosurfactants using renewable cellulose‐derived feedstocks

AbstractGlycolipids produced and secreted by oleaginous yeasts are renewable compounds with important physico‐chemical properties, and multiple biological and industrial applications. The large‐scale production of these compounds has been limited by high production costs and low yields. The sophorolipid‐producing yeast Pseudohyphozyma bogoriensis may possess the ability to grow in fermentation systems using carbon substrates deriving from inexpensive lignocellulosic biomass, while simultaneously secreting high value biomaterials. In this study, comparative analyses between different cellulose‐derived carbon sources including glucose, cellobiose, and sodium carboxymethyl cellulose confirmed the ability of P. bogoriensis to grow and accumulate glycolipids using these substrates. On a dry weight basis, the highest yields of about 4% (wt/wt) glycolipids were obtained when cellobiose was supplemented at 10 g/L in shake‐flask fermentations. When the unconventional carbon substrate sodium carboxymethyl cellulose was supplemented, cultures exhibited a lower glycolipid yield of 0.3% (wt/wt), but the dry weight was higher compared to other substrates. Analytical analyses using various chromatography methods confirmed the chemical profiles, whereas both monoacetylated and diacetylated sophorolipid forms with 22 carbon long‐chain hydroxy fatty acid were identified in all glycolipid extracts. Surface tension (ST) and critical micelle concentration (CMC) measurements showed that glycolipids produced on cellulose‐derived substrates exhibited similar or even superior physical properties compared with glucose. Furthermore, availability of the yeast genome sequences facilitated the identification of putative genes that may be involved in cellulose hydrolysis (e.g., cellulase‐like). Information on genomic and metabolic pathways is a prerequisite for trait improvement toward increasing the production of high value biomaterials.

Valorization of waste engine oil to mono- and di-rhamnolipid in a sustainable approach to circular bioeconomy.

This study aims to valorize waste engine oil (WEO) for synthesizing economically viable biosurfactants (rhamnolipids) to strengthen the circular bioeconomy concept. It specifically focuses on investigating the influence of key bioprocess parameters, viz. agitation and aeration rates, on enhancing rhamnolipid yield in a fed-batch fermentation mode. The methodology involves conducting experiments in a stirred tank bioreactor (3 L) using Pseudomonas aeruginosa gi |KP 163922| as the test organism. Central composite design and response surface methodology (CCD-RSM) are employed to design the experiments and analyze the effects of agitation and aeration rates on various parameters, including dry cell biomass (DCBM), surface tension, tensoactivity, and rhamnolipid yield. It is also essential to determine the mechanistic pathway of biosurfactant production followed by the strain using complex hydrophobic substrates such as WEO. The study reveals that optimal agitation and aeration rates of 200rpm and 1 Lpm result in the highest biosurfactant yield of 29.76g/L with minimal surface tension (28 mN/m). Biosurfactant characterization using FTIR, 1H NMR, and UPLC-MS/MS confirm the presence of dominant molecular ion peaks m/z 543.9 and 675.1. This suggests that the biosurfactant is a mixture of mono- and di-rhamnolipids (RhaC10C10, RhaRhaC10C12:1, RhaRhaC12:1C10). The findings present a sustainable approach for biosurfactant production in a fed-batch bioreactor. This research opens the possibility of exploring the use of pilot or large-scale bioreactors for biosurfactant production in future investigations.

Biosurfactants production by some Aspergilli species under solid state fermentation

Biosurfactants production by some Aspergilli species under solid state fermentation

Serratia rubidaea SNAU02-mediated biosurfactant production from cashew apple bagasse: A promising biotechnological strategy for environmental sustainability

Serratia rubidaea SNAU02 (S. rubidaea SNAU02), a promising microbial strain, has been explored for its capability to produce biosurfactants using cashew apple bagasse as a sustainable carbon source. This study investigates the biotechnological potential of S. rubidaea SNAU02 in the context of environmental sustainability. Cashew apple bagasse, an agro-industrial waste, serves as an inexpensive and renewable substrate for biosurfactant production, contributing to waste valorization and reducing environmental impact. The biosurfactant produced by S. rubidaea SNAU02 demonstrates multifaceted applications, including enhanced oil recovery, bioremediation, and detergent formulation. The isolation and characterization of the biosurfactant reveal its stability under a range of environmental conditions, suggesting its potential for diverse industrial applications. The study also assesses the biocompatibility and ecotoxicity of the biosurfactant, emphasizing its eco-friendly nature. Furthermore, production process optimization and scale-up strategies are explored to enhance the economic viability of biosurfactant production. The findings of this research underscore the significance of integrating microbial biotechnology with waste utilization, offering a sustainable solution for environmental challenges. S. rubidaea SNAU02-mediated biosurfactant production from cashew apple bagasse emerges as a promising biotechnological strategy that aligns with the principles of environmental sustainability, contributing to the development of green and eco-friendly technologies.

Assessing the feasibility and sustainability of a surfactin production process: a techno-economic and environmental analysis.

Biosurfactants have been profiled as a sustainable replacement for chemical-based surfactants since these bio-based molecules have higher biodegradability. Few research papers have focused on assessing biosurfactant production to elucidate potential bottlenecks. This research aims to assess the techno-economic and environmental performance of surfactin production in a potential scale of 65m3, considering different product yields and involving the European energy crisis of 2021-2022. The conceptual design, simulation, techno-economic, and environmental assessments were done by applying process engineering concepts and software tools such as Aspen Plus v.9.0 and SimaPro v.8.3.3. The results demonstrated the high economic potential of surfactin production since the higher values in the market offset the low fermentation yields, low recovery efficiency, and high capital investment. The sensitivity analysis of the economic assessment elucidated a minimum surfactin selling price between 29 and 31 USD/kg of surfactin, while a minimum processing scale for economic feasibility between 4 and 5kg/h is needed to reach an equilibrium point. The environmental performance must be improved since the carbon footprint was 43kg CO2eq/kg of surfactin. The downstream processing and energy demand are the main bottlenecks since these aspects contribute to 63 and 25% of the total emissions. The fermentation process and downstream process are key factors for future optimization and research.

Yarrowia lipolytica CMGB32 Biosurfactants Produced Using n-Hexadecane: Developing Strategies for Environmental Remediation

The yeast Yarrowia lipolytica degrades petroleum compounds, including alkanes, via the monoterminal oxidation pathway, the hydrophobic carbon substrate assimilation is mediated by biosurfactants, and extracellular amphiphilic molecules are produced by the yeast cell. This study focuses on the ability of the strain Y. lipolytica CMGB32 to degrade n-hexadecane by producing biosurfactants with high potential for bioremediation. The hydrocarbon-degrading potential of the yeast strain was observed via a 2,6-dichlorophenolindophenol (DCPIP) test in Bushnell–Hass medium with 1% n-hexadecane, and cell hydrophobicity was expressed as microbial adhesion to hydrocarbons (MATH). Biosurfactant production on yeast peptone (YP) with 1% n-hexadecane was estimated after 72 h using the emulsification index (E24%) against toluene. Crude biosurfactant (cell-free broth) stability tests were performed at different temperatures (4 °C, 70 °C) and NaCl concentrations (2–10%). The effects of a biosurfactant on synthetic wastewater remediation comprised the growth curves (OD measurements) of natural heavy metal degrader Rhodotorula mucilaginosa, determination of nutrients (spectrophotometrically), physico-chemical parameters, and removal capacity of lead and cadmium ions (via inductively coupled plasma mass spectrometry—ICP-MS). The antimicrobial and anti-adherence activities of 20 mg/mL and 40 mg/mL of the biosurfactant against pathogenic Candida krusei strains involved growth observations and the crystal violet microtiter method. The DCPIP decolorization occurred after six days, corresponding to the maximum growth phase of the Y. lipolytica culture. After 72 h, the cells presented high hydrophobicity (82.61% MATH) and stable biosurfactant production (E24% 47%). The crude biosurfactant (5%) increased the growth of R. mucilaginosa strains cultivated on synthetic wastewater cultures contaminated with Pb2+ and Cd2+, increased the conductivity and COD (86%) of the samples, and determined Pb2+ (66%) and Cd2+ (42%) ions reduction. The concentrated biosurfactant inhibited C. krusei growth (70%) and biofilm adherence. In conclusion, Y. lipolytica CMGB32 shows important potential for development of biosurfactant-based technologies for the remediation of heavy-metal- and emerging pathogen-contaminated wastewaters.

Utilization of lasso peptides for biodegradation of polycyclic aromatic hydrocarbons.

Many microbial genes involved in degrading recalcitrant environmental contaminants such as polycyclic aromatic hydrocarbons (PAHs) have been identified and characterized. However, all molecular mechanisms required for PAH utilization have not yet been elucidated. In this work, we demonstrate the proposed involvement of lasso peptides in the utilization of the PAH phenanthrene in Sphingomonas BPH. Transpositional mutagenesis of Sphingomonas BPH with the miniTn5 transposon yielded 3 phenanthrene utilization deficient mutants, #257, #1778, and #1782. In mutant #1782, Tn5 had inserted into the large subunit of the naph/bph dioxygenase gene. In mutant #1778, Tn5 had inserted into the B2 protease gene of a lasso peptide cluster. This finding is the first report on the role of lasso peptides in PAH utilization. Our studies also demonstrate that interruption of the lasso peptide cluster resulted in a significant increase in the amount of biosurfactant produced in the presence of glucose when compared to the wild-type strain. Collectively, these results suggest that the mechanisms Sphingomonas BPH utilizes to degrade phenanthrene are far more complex than previously understood and that the #1778 mutant may be a good candidate for bioremediation when glucose is applied as an amendment due to its higher biosurfactant production.

Insights into the degradation of diesel-contaminated seawater through natural microbiota and culturable microorganisms: The overlook role of extracellular polymeric substances (EPS)

The role of EPS produced during biodegradation diesel-contaminated seawater, as well as the effect of EPS on natural microbiota and culturable microorganisms, remains unknown. Here, natural microbiota (pre and post enrichment with diesel) from 5 islands’ seawater in Jiaozhou Bay were explored through metagenomic and culture-dependent approaches. EPS response degradation was mainly characterized by the following aspects: 1) The post-enrichment samples contained significantly fewer dominant bacterial genera than the pre-enrichment samples, and EPS or PS (polysaccharides) promoted degradation of C16-C24 hydrocarbon fractions; 2) EPS caused higher increases in aromatic compound degradation functional genes copies; 3) EPS enhanced the enzymatic activity of alkane hydroxylase and ethanol dehydrogenase; 4) Diesel degradation by mono and mixed cultures of culturable bacteria (B1 and B2) with extracted EPS showed a higher biomass, biosurfactant production, expression of PAH-RHDα GN and cytochrome P450 genes, degradability and emulsification capacity. The above innovations provided new perspectives for oil-spill bioremediation.

Biosurfactant production by a crude oil‐utilizing bacterium towards petroleum hydrocarbon biodegradation applications

AbstractBiosurfactants produced by microorganisms are green amphiphilic biomolecules. They have numerous advantages compared to chemical surfactants including a lower toxicity, better environmental compatibility and effective and stable properties under extreme conditions such as a wide range of temperature, pH and salinity. A highly bio‐surfactant‐producing strain of Bacillus, VTVK15 was selected among the Bacillus isolates from marine environment and oil contaminated sites in Ba Ria‐Vung Tau. Sequence analysis of 16S rDNA showed that the VTVK15 strain was 99% similar with 16s rDNA sequence of Bacillus megaterium. The suitable conditions for the bio‐surfactant production by the strain VTVK15 were 37 °C, pH 7; 2% w/v and 0.4% w/v for temperature, initial solution pH, concentration of carbon substrate (crude oil), and concentration of nitrogen substrate ((NH4)2SO4), respectively. The emulsification index (E24) increased from 51.8% to 67.7% with suitable conditions. The petroleum hydrocarbon degradation (TPH) efficiency by the strain Bacillus megaterium VTVK15 in crude oil estimated using TPH analysis was 72% after 14 days. These results revealed that the strain VTVK15 exhibited a tremendous potential for bioremediation of petroleum hydrocarbon contaminants.