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.

Inulin from halophilic archaeon Haloarcula: Production, chemical characterization, biological, and technological properties

Halophilic archaea are capable of producing fructans, which are fructose-based polysaccharides. However, their biochemical characterization and biological and technological properties have been scarcely studied. The aim of this study was to evaluate the production, chemical characterization, biological and technological properties of a fructan inulin-type biosynthesized by a halophilic archaeon. Fructan extraction was performed through ethanol precipitation and purification by diafiltration. The chemical structure was elucidated using Fourier Transform-Infrared Spectroscopy and Nuclear Magnetic Resonance (NMR). Haloarcula sp. M1 biosynthesizes inulin with an average molecular weight of 8.37 × 106 Da. The maximal production reached 3.9 g of inulin per liter of culture within seven days. The glass transition temperature of inulin was measured at 138.85 °C, and it exhibited an emulsifying index of 36.47 %, which is higher than that of inulin derived from chicory. Inulin from Haloarcula sp. M1 (InuH) demonstrates prebiotic capacity. This study represents the first report on the biological and technological properties of inulin derived from halophilic archaea.

Candida krusei M4CK Produces a Bioemulsifier That Acts on Melaleuca Essential Oil and Aids in Its Antibacterial and Antibiofilm Activity

Surface-active compounds (SACs) of microbial origin are an active group of biomolecules with potential use in the formulation of emulsions. In this sense, the present study aimed to isolate and select yeasts from fruits that could produce SACs for essential oil emulsions. The Candida krusei M4CK was isolated from the Byrsonima crassifolia fruit to make SACs. This emulsification activity (E24) was equal to or greater 50% in all carbon sources, such as olive oil, sunflower oil, kerosene, hexane, and hexadecane. E24 followed exponential growth according to the growth phase. The stability of emulsions was maintained over a wide range of temperatures, pH, and salinity. The OMBE4CK (melaleuca essential oil emulsion) had better and more significant inhibitory potential for biofilm reduction formation. In addition, bioemulsifier BE4CK alone on Escherichia coli and Pseudomonas aeruginosa biofilm showed few effective results, while there was a significant eradication for Staphylococcus aureus biofilms. The biofilms formed by S. aureus were eradicated in all concentrations of OMBE4CK. At the same time, the preformed biofilm by E. coli and P. aeruginosa were removed entirely at concentrations of 25 mg/mL, 12.5 mg/mL, and 6.25 mg/mL. The results show that the bioemulsifier BE4CK may represent a new potential for antibiofilm application.

Polyphosphate accumulation and cell-surface properties by autochthonous bacteria from Argentinian Patagonia

Bacteria persisting in environments contaminated with polycyclic aromatic hydrocarbons (PAHs) have developed physiological mechanisms to counteract environmental stress. Inorganic polyphosphate accumulation represents one of these possible mechanisms. Likewise, properties such as cell-surface hydrophobicity, auto-aggregation, biofilm formation and bioemulsifying activity could facilitate interaction of microorganisms with hydrophobic organic compounds. In this work, these physiological properties were compared in indigenous bacteria from polluted sediments from Argentinian Patagonia, which were cultivated in two culture media (LBm and JPP) as a way to improve in the next future the PAHs removal. The highest hydrophobicity values were obtained in Rhodococcus strains, while Bacillus sp. B18 showed the highest auto-aggregation percentage and emulsion index. The highest numerical values of biofilm formation were determined in Rhodococcus sp. F27, Pseudomonas sp. P26, and Gordonia sp. H19 either on hydrophilic or on hydrophobic support. The qualitative and quantitative polyP determinations confirmed the presence of this biopolymer in the strains evaluated. The highest intracellular phosphate mean values were obtained in Bacillus sp. B18 in LBm and Rhodococcus erythropolis 20 in JPP. The bacteria evaluated belonging to different genera showed significant differences in their cell-surface characteristics, bioemulsifying activity and polyP accumulation. The low-cost JPP culture medium was selected for future contaminant removal studies.

Assessment of Rheological Behaviour of Water-in-Oil Emulsions Mediated by Glycolipid Biosurfactant Produced by Bacillus megaterium SPSW1001

A screening programme using mineral salt medium supplemented with n-hexadecane resulted in isolating a Bacillus megaterium SPSW1001 which was capable of producing surface active molecules lowering culture medium surface tension to 27.43 ± 0.029 mN/m and interfacial tension to 0.38 ± 0.03 mN/m at 72 h and an emulsification index (E24) (85.63%). The biosurfactant product was further used to assess its effects on the rheological characteristics of water-in-oil emulsion prepared with engine oil. Structural characterization of the biosurfactant product by FTIR revealed a C-O-C stretch in sugar moiety and ester carbonyl linkage group between sugar and fatty acids, respectively, while mass spectral analysis revealed its glycolipid nature, with an m/z value of 662.44. The fluid behaviour of water-in-oil emulsion showed a non-Newtonian viscoelastic dilatant flow after yielding exemplified appropriately by Herschel-Bulkley model with 100% confidence of fit. The present study is significant in formulation and handling, processing, and transport of emulsion and in understanding flocculation characteristics.

Biosurfactant production by halophilic yeasts isolated from extreme environments in Botswana

Nine morphologically distinct halophilic yeasts were isolated from Makgadikgadi and Sua pans, as pristine and extreme environments in Botswana. Screening for biosurfactant production showed that Rhodotorula mucilaginosa SP6 and Debaryomyces hansenii MK9 exhibited the highest biosurfactant activity using Xanthocercis zambesiaca seed powder as a novel and alternative inexpensive carbon substrate. Chemical characterization of the purified biosurfactants by Fourier Transform Infra-Red spectroscopy suggested that the biosurfactant from R. mucilaginosa SP6 was a rhamnolipid-type whereas the biosurfactant from D. hansenii MK9 was a sophorolipid-type. The two biosurfactants exhibited antimicrobial activities against eight pathogenic bacteria and fungal strains (Proteus vulgaris, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Micrococcus luteus, Cryptococcus neoformans, Candida albicans and Aspergilus niger). The sophorolopid-type biosurfactant was found to be the most potent among the antimicrobial drug resistant strains tested. The findings open up prospects for the development of environmentally friendly antimicrobial drugs that use an inexpensive source of carbon to reduce the costs associated with the production of biosurfactants.

Wastewater from the Edible Oil Industry as a Potential Source of Lipase- and Surfactant-Producing Actinobacteria

Wastewaters generated from various stages of edible oil production in a canola processing facility were collected with the aim of determining the presence of lipase-producing actinobacteria of potential industrial significance. The high chemical oxygen demand (COD) readings (up to 86,700 mg L⁻¹ in some samples) indicated that the wastewater exhibited the nutritional potential to support bacterial growth. A novel approach was developed for the isolation of metagenomic DNA from the oil-rich wastewater samples. Microbiota analysis of the buffer tank and refinery condensate tank wastewater samples showed a dominance of Cutibacterium acnes subsp. defendens, followed by a limited number of other actinobacterial genera, indicating the presence of a highly specialized actinobacterial population. Cultured isolates with typical actinobacterial morphology were analyzed for their ability to produce lipases and biosurfactants. Two strains, designated as BT3 and BT4, exhibited the highest lipase production levels when grown in the presence of tributyrin and olive oil (1.39 U mg⁻¹ crude protein and 0.8 U mg⁻¹ crude protein, respectively) and were subsequently definitively identified by genome sequencing to be related to Streptomyces albidoflavus. Cultivation of the strains in media containing different types of oils did not markedly increase the level of enzyme production, with the exception of strain BT4 (1.0 U mg⁻¹ crude protein in the presence of peanut oil). Genome sequencing of the two strains, BT3 and BT4, revealed the presence of a range of lipase and esterase genes that may be involved in the production of the enzymes detected in this study. The presence of gene clusters involved in the production of biosurfactants were also detected, notably moreso in strain BT3 than BT4.

Characterization of Dietzia maris AURCCBT01 from oil-contaminated soil for biodegradation of crude oil

A bacterial strain was isolated from an oil-contaminated site and on its' further characterization, exhibited the potential of synthesising metabolites and the ability to degrade crude oil. Its' morphological, biochemical and 16S rRNA analysis suggested that the bacterium belongs to Dietzia maris AURCCBT01. This strain rapidly grew in the medium supplemented with n-alkanes C14, C18, C20, C28 and C32 utilizing them as a sole carbon source and produced a maximum canthaxanthin pigment of 971.37 µg/L in the n-C14 supplemented medium and produced the lowest pigment yield of 389.48 µg/L in the n-C-32 supplemented medium. Moreover, the strain effectively degraded 91.87% of crude oil in 7 days. The emulsification activity of the strain was 25% with the highest cell surface hydrophobicity (70.26%) and it showed a decrease in surface tension, indicating that the biosurfactant production lowers the surface tension. This is the first report on the characterization of the strain, Dietzia maris AURCCBT01 and its' novelty of alkane degradation and simultaneous production of canthaxanthin pigment.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02807-7.

Influence of rhamnolipid biosurfactant and Brij-35 synthetic surfactant on 14C-Pyrene mineralization in soil

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants in soil and are considered priority pollutants due to their carcinogenicity. Bioremediation of PAH-contaminated soils is often limited by the low solubility and strong sorption of PAHs in soil. Synthetic surfactants and biosurfactants have been used to enhance the bioavailability of PAHs and to accelerate microbial degradation. However, few studies have compared synthetic and biosurfactants in their efficiency in promoting PAH biodegradation in either native or bioaugmented soils. In this study, we evaluated mineralization of ¹⁴C-pyrene in soils with or without the augmentation of Mycobacterium vanbaalenii PYR-1, and characterized the effect of Brij-35 (synthetic) and rhamnolipid biosurfactant at different amendment rates. Treatment of rhamnolipid biosurfactant at 140 or 1400 μg surfactant g-dry soil^-1 rates resulted in a significantly longer lag period in ¹⁴C-pyrene mineralization in both native and bioaugmented soils. In contrast, amendment of Brij-35 generally increased ¹⁴C-pyrene degradation, and the greatest enhancement occurred at 21.6 or 216 μg surfactant g-dry soil^-1 rates, which may be attributed to increased bioavailability. Brij-35 and rhamnolipid biosurfactant were found to be non-toxic to M. vanbaalenii PYR-1 at 10X CMC, thus indicating rhamnolipid biosurfactant likely served as a preferential carbon source to the degrading bacteria in place of ¹⁴C-pyrene, leading to delayed and inhibited ¹⁴C-pyrene degradation. Mineralization of ¹⁴C-pyrene by M. vanbaalenii PYR-1 was rapid in the unamended soils, and up to 60% of pyrene was mineralized to ¹⁴CO₂ after 10 d in the unamended or Brij-35 surfactant-amended soils. Findings of this study suggest that application of surfactants may not always lead to enhanced PAH biodegradation or removal. If the surfactant is preferentially used as an easier carbon substrate than PAHs for soil microorganisms, it may actually inhibit PAH biodegradation. Selection of surfactant types is therefore crucial for the effectiveness of surfactant-aided bioremediation of PAH-contaminated soils.

Characterization of Crude Oil Degrading Bacteria Isolated from Contaminated Soils Surrounding Gas Stations

A total of twenty bacterial cultures were isolated from hydrocarbon contaminated soil. Of the 20 isolates, RAM03, RAM06, RAM13, and RAM17 were specifically chosen based on their relatively higher growth on salt medium amended with 4 % crude oil, emulsion index, surface tension, and degradation percentage. These bacterial cultures had 16S rRNA gene sequences that were most similar to Ochrobactrum cytisi (RAM03), Ochrobactrum anthropi (RAM06 and RAM17), and Sinorhizobium meliloti (RAM13) with 96 %, 100 % and 99 %, and 99 % similarity. The tested strains revealed a promising potential for bioremediation of petroleum oil contamination as they could degrade >93 % and 54 % of total petroleum hydrocarbons (TPHs) in a liquid medium and soil amended with 4 % crude oil, respectively, after 30 day incubation. These bacteria could effectively remove both aliphatic and aromatic petroleum hydrocarbons. In conclusion, these strains could be considered as good prospects for their application in bioremediation of hydrocarbon contaminated environment.

Production of bioemulsifiers by Amycolatopsis tucumanensis DSM 45259 and their potential application in remediation technologies for soils contaminated with hexavalent chromium

In recent years, increasing interest has been shown in the use of bioemulsifiers as washing agents that can enhance desorption of soil-bound metals. However, high production costs derived from the use of expensive substrates for formulation of the fermentation media represent the main challenge for full, large-scale implementation of bioemulsifiers. This work reports on a first study of bioemulsifier production by the actinobacterium Amycolatopsis tucumanensis DSM 45259 using different carbon and nitrogen sources. Preliminary results on the potential use of these compounds as washing agents for soils contaminated with Cu(II) and Cr(VI) are also presented. The best specific production was detected using glycerol and urea as carbon and nitrogen substrates, respectively. However, with all of the substrates used during the batch assay, the bioemulsifiers showed high levels of stability at extreme conditions of pH, temperature, and salt concentration. Under the current assay conditions, the bioemulsifiers were not effective in removing Cu(II) from soil. However, they were able to mediate Cr(VI) recovery, with the removal percentage doubled compared to that seen when using deionized water. These findings appear promising for the development of remediation technologies for hexavalent chromium compounds based upon direct use of these microbial emulsifiers.

Production and partial characterization of bioemulsifier from a chromium-resistant actinobacteria

Surface-active compounds such as synthetic emulsifiers have been used for several decades, both for the degradation of hydrocarbons and increasing desorption of soil-bound metals. However, due to their high toxicity, low degradability, and production costs unaffordable for use in larger ecosystems, synthetic emulsifiers have been gradually replaced by those derived from natural sources such as plants or microbes. In previous studies, the bacterium Streptomyces sp. MC1 has shown the ability to reduce and/or accumulate Cr(VI), a highly promising advance in the development of methods for environmental clean-up of sites contaminated with chromium. Here, new studies on the production of emulsifier from this strain are presented. The cultivation factors that have a significant influence on emulsifier biosynthesis, as well as the interactions among them, were studied by factorial design. Based upon optimization studies, maximum bioemulsifier production was detected in the culture medium having an initial pH of 8 with phosphate 2.0 g L(-1) and Ca(+2) 1.0 g L(-1) added, with an emulsification index about 3.5 times greater compared to the basal value. Interestingly, in the presence of 5.0 g L(-1) Cr(VI), Streptomyces sp. MC1 retained about 65% of its emulsifier production ability. Partially purified emulsifier presented high thermo-stability and partial water solubility. These findings could have promising future prospects for the remediation of organic- and metal-contaminated sites.

Surface-active potential of biosurfactants produced in curd whey by Pseudomonas aeruginosa strain-PP2 and Kocuria turfanesis strain-J at extreme environmental conditions

Surface-active potential of biosurfactants produced cost-effectively in curd whey by Pseudomonas aeruginosa strain-PP2 and Kocuria turfanesis strain-J were tested using parameters viz. surface tension (ST) reduction, F(CMC) (highest dilution factor to reach critical micelle concentration) and emulsification index (EI-24) of pesticides; monocrotophos and imidacloprid at extreme environmental conditions. Results have shown that ST reduction of biosurfactants was stable at pH 2-11. High F(CMC) of the biosurfactant in the fermented whey at low pH improved emulsification of pesticides. ST marginally increased at 5% and 15% NaCl, resulting in high EI-24 and F(CMC). Over a range of temperatures 30-121 °C, ST remained low with a higher F(CMC) and EI-24 at 60 °C than at 121 and 30 °C. The biosurfactants have shown differences in their surface-active property and have marked specificity to emulsify pesticides in extreme environmental conditions.

Emulsification potential of a newly isolated biosurfactant-producing bacterium, Rhodococcus sp. strain TA6

An indigenous biosurfactant producing bacterium, Rhodococcus sp. strain TA6 was isolated from Iranian oil contaminated soil using an efficient enrichment and screening method. During growth on sucrose and several hydrocarbon substrates as sole carbon source, the bacterium could produce biosurfactants. As a result of biosurfactant synthesis, the surface tension of the growth medium was reduced from 68mNm(-1) to values below 30mNm(-1). The biosurfactant was capable of forming stable emulsions with various hydrocarbons ranging from pentane to light motor oil. Preliminary chemical characterization revealed that the TA6 biosurfactant consisted of extracellular lipids and glycolipids. The biosurfactant was stable during exposure to high salinity (10% NaCl), elevated temperatures (120°C for 15min) and within a wide pH range (4.0-10.0). The culture broth was effective in recovering up to 70% of the residual oil from oil-saturated sand packs which indicates the potential value of the biosurfactant in enhanced oil recovery.

Screening concepts for the isolation of biosurfactant producing microorganisms

This chapter gives an overview of current methods for the isolation of biosurfactant producing microbes. The common screening methods for biosurfactants are presented. Sampling and isolation of bacteria are the basis for screening of biosurfactant producing microbes. Hydrocarbon-contaminated sites are the most promising for the isolation of biosurfactant producing microbes, but many strains have also been isolated from undisturbed sites. In subsequent steps the isolates have to be characterized in order to identify the strains which are interesting for a further investigation. Several techniques have been developed for identifying biosurfactant producing strains. Most of them are directly based on the surface or interfacial activity of the culture supernatant. Apart from that, some screening methods explore the hydrophobicity of the cell surface. This trait also gives an indication on biosurfactant production. In recent years automation and miniaturization have led to the development of high throughput methods for screening. High throughput screening (HTS) for analyzing large amounts of potential candidates or whole culture collections is reflected in the end. However, no new principals have been introduced by HTS methods.

Comparison of methods to detect biosurfactant production by diverse microorganisms

Three methods to detect biosurfactant production, drop collapse, oil spreading, and blood agar lysis, were compared for their ease of use and reliability in relation to the ability of the cultures to reduce surface tension. The three methods were used to test for biosurfactant production in 205 environmental strains with different phylogenetic affiliations. Surface tension of select strains that gave conflicting results with the above three methods was also measured. Sixteen percent of the strains that lysed blood agar tested negative for biosurfactant production with the other two methods and had little reduction in surface tension (values above 60 mN/m). Thirty eight percent of the strains that did not lyse blood agar tested positive for biosurfactant production with the other two methods and had surface tension values as low as 35 mN/m. There was a very strong, negative, linear correlation between the diameter of clear zone obtained with the oil spreading technique and surface tension (rs = -0.959) and a weaker negative correlation between drop collapse method and surface tension (rs = -0.82), suggesting that the oil spreading technique better predicted biosurfactant production than the drop collapse method. The use of the drop collapse method as a primary method to detect biosurfactant producers, followed by the determination of the biosurfactant concentration using the oil spreading technique, constitutes a quick and easy protocol to screen and quantify biosurfactant production. The large number of false negatives and positives obtained with the blood agar lysis method and its poor correlation to surface tension (rs = -0.15) demonstrated that it is not a reliable method to detect biosurfactant production.

R-bodies in Pseudomonas aeruginosa strain 44T1

For the first time R-bodies are described in a new strain 44T1 of Pseudomonas aeruginosa. Its size was measured as being 0.22 to 0.37 microns of width per 0.27 to 0.41 microns of length and 5 to 9 spiral turns about 16 nm. These structures are similar to previously observed in bacteria and are related with physiological state of bacteria in minimal conditions of growth.

Analysis of glycolipids by fast atom bombardment mass spectrometry

The positive and negative ion fast atom bombardment (FAB) mass spectra of four glycolipids obtained from microbial cultures are reported. The spectra of the glycolipids in the positive ion mode are characterized by abundant [M + Na]+, [M + Na + matrix]+ and [M + 2Na - H]+ species. In negative FAB conditions the molecules yield [M - H]-. Our understanding of the FAB behaviour of glycolipids in both positive and negative modes has been considerably aided in the structure elucidation, without any derivatization or degradation reaction of the compounds studied. The technique allows unambiguous molecular weight determination of low-microgram amounts of these glycolipids purified from biological sources and provides useful fragmentation information.