Production of bioemulsifier by Bacillus subtilis, Alcaligenes faecalis and Enterobacter species in liquid culture

Amelioration of lipopeptide biosurfactants for enhanced antibacterial and biocompatibility through molecular antioxidant property by methoxy and carboxyl moieties

Biosurfactants having surface-active biomolecules have been the cynosure in environment research due to their vast application. However, the lack of information about their low-cost production and detailed mechanistic biocompatibility limits the applicability. The study explores techniques for the production and design of low-cost, biodegradable, and non-toxic biosurfactants from Brevibacterium casei strain LS14 and excavates the mechanistic details of their biomedical properties like antibacterial effects and biocompatibility. Taguchi's design of experiment was used to optimize for enhancing biosurfactant production by optimal factor combinations like Waste glycerol (1%v/v), peptone (1%w/v), NaCl 0.4% (w/v), and pH 6. Under optimal conditions, the purified biosurfactant reduced the surface tension to 35 mN/m from 72.8 mN/m (MSM) and a critical micelle concentration of 25 mg/ml was achieved. Spectroscopic analyses of the purified biosurfactant using Nuclear Magnetic Resonance suggested it as a lipopeptide biosurfactant. The evaluation of mechanistic antibacterial, antiradical, antiproliferative, and cellular effects indicated the efficient antibacterial activity (against Pseudomonas aeruginosa) of biosurfactants due to free radical scavenging activity and oxidative stress. Moreover, the cellular cytotoxicity was estimated by MTT and other cellular assays revealing the phenomenon as the dose-dependent induction of apoptosis due to free radical scavenging with an LC50 of 55.6 ± 2.3 mg/ml.

Production and characterization of bioemulsifier by Parapedobacter indicus

The current study evaluated Parapedobacter indicus MCC 2546 for its potential to produce a bioemulsifier (BE). Screening methods performed for BE production by P. indicus MCC 2546 showed good lipase activity, positive drop collapse test, and oil-spreading activity. Furthermore, it showed maximum emulsification activity (225 EU/ml) and emulsification index (E24 50%) at 37°C in Luria Bertani broth at 72 h with olive oil as a substrate. The optimal pH and NaCl concentration for maximum emulsification activity were 7 and 1%, respectively. P. indicus MCC 2546 lowered the surface tension of the culture medium from 59.65 to 50.42 ± 0.78 mN/m. BE produced was composed of 70% protein and 30% carbohydrate, which showed the protein-polysaccharide nature of the BE. Furthermore, Fourier transform infrared spectroscopy analysis confirmed the same. P. indicus MCC 2546 showed a catecholate type of siderophore production. This is the first report on BE and siderophore production by the genus Parapedobacter.

Bioremediation of petroleum hydrocarbon contaminated soil by microorganisms immobilized on sludge modified by non-ionic surfactant

The immobilization of microorganisms on high-quality and inexpensive carriers to remediate oil-contaminated soil is an effective strategy for contaminated soil remediation. Due to the abundance in nutrients, large specific surface area, and fewer pathogens, the composting sludge is considered a high-quality immobilized material. Herein, two non-ionic surfactants, TW-80 and sophorolipid, were used to modify composted sludge. High-efficiency petroleum hydrocarbon-degrading bacteria groups selected in the laboratory were fixed on the modified composting sludge under optimal conditions. The immobilized material was placed in the soil contaminated by petroleum hydrocarbons at an additive amount of 2wt/%, and a simulated remediation experiment was performed for 90 days. Both soil properties and microbial structure were characterized. Surfactant-modified compost sludge enhances the adsorption capacity to petroleum hydrocarbon. The immobilized microorganisms in the modified compost sludge showed a good effect on the remediation of soil contaminated by petroleum hydrocarbons. In addition, immobilized materials also increase the diversity of the microbial community structure in the soil. High-efficiency petroleum hydrocarbon-degrading bacteria immobilized on surfactant-modified compost can effectively promote the degradation of petroleum hydrocarbons in the soil and increase the abundance of microorganisms in the soil. It shows the feasibility of eco-friendly remediation of hydrocarbon-contaminated soil.

Identification of cultivable bacterial strains producing biosurfactants/bioemulsifiers isolated from an Algerian oil refinery

Algerian petrochemical industrial areas are usually running spills and leakages of hydrocarbons, which constitutes a major source of toxic compounds in soil such as aromatic hydrocarbons. In this paper, samples of crude oil-polluted soil were collected from Skikda's oil refinery and were subjected to mono and polyaromatic hydrocarbons threshold assessment. Soil physicochemical parameters were determined for each sample to examine their response to pollution. Amid 34 isolated bacteria, eleven strains were selected as best Biosurfactants (Bs)/Bioemulsifiers (Be) producers and were assigned to Firmicutes and Proteobacteria phyla based on molecular identification. Phylogenetic analysis of partial 16S rDNA gene sequences allowed the construction of evolutionary trees by means of the maximum likelihood method. Accordingly, strains were similar to Bacillus spp., Priesta spp., Pseudomonas spp., Enterobacter spp. and Kosakonia spp. with more than 95% similarity. These strains could be qualified candidates for an efficient bioremediation process of severally polluted soils.

A comparative study on chemical characterization and properties of surface active compounds from Gram-positive Bacillus and Gram-negative Ochrobactrum strains utilizing pure hydrocarbons and waste mineral lubricating oils

Mineral lubricating oils are widely used in various industrial sectors for their applications in maintenance and functioning of machineries. However, indiscriminate dumping of these used oils have resulted in polluting the natural reservoirs which subsequently destroys ecological balance. Bacteria can emulsify or lower surface tension between phases of immiscible substrates and can acquire them as their carbon and energy sources. Such a phenomenon is mediated by production of extracellular polymers which can function as eminent surface active compounds based on their surfactant or emulsifying nature. The comparison between bacterial strains (Gram-positive Bacillus stratosphericus A15 and Gram-negative Ochrobactrum pseudintermedium C1) on utilization of pure straight chain hydrocarbons, waste mineral lubricating oils as sole carbon source and chemical characterization of the synthesized surface active compounds were studied. Characterization analysis by Ultraviolet Visible spectrophotometry, Fourier transform infrared spectroscopy, Nuclear Magnetic Resonance spectroscopy, Carbon-Hydrogen-Nitrogen analysis has given detailed structural elucidation of surface active compounds. The contrasting nature of bacterial strains in utilization of different hydrocarbons of waste mineral lubricating oils was observed in Gas Chromatography-Mass Spectroscopy analysis. The variation between both strains in utilization of hydrocarbons can be manifested in chemical structural differences and properties of the produced surface active compounds. Scanning Electron Microscopy has given detailed insight into the microstructural difference of the compounds. The utilization of lubricating oils can address waste disposal problem and offer an economical feasible approach for bacterial production of surface active compounds. Our results suggest that these surface active compounds can maneuver applications in environmental bioremediation and agriculture, pharmaceuticals and food as functional biomaterials.

Modified coir pith with glucose syrup as a supporter in non-external nutrient supplied biofilter for benzene removal by Bacillus megaterium

Coir pith glucose syrup beads were used as a supporter in a biofilter system. The modified coir pith beads provided a carbon source and controlled humidity for microorganism growth for long-term operation without external nutrient supplementation. For the screening, Bacillus spp. were immobilised on coir pith beads and used for benzene bioremediation. The result showed that coir pith beads immobilised with Bacillus megaterium can remove on average 85-100% of the benzene (215-day operation). In addition, B. megaterium presented the ability to transform benzene to catechol. For an up-scaled application, a 25-L biofilter system was developed and tested in a closed 24-m³ container re-injected with 0.6 ppm benzene for 8 cycles. The system presented the ability to remove 100% of the benzene. This biofilter has the potential to be applied in a real benzene-contaminated site.

Eco-Friendly Bioemulsifier Production by Mucor circinelloides UCP0001 Isolated from Mangrove Sediments Using Renewable Substrates for Environmental Applications

The successful production of a biosurfactant is dependent on the development of processes using low cost raw materials. In the present work, an economically attractive medium composed of corn steep liquor and waste cooking oil was formulated to maximize the production of bioemulsifier by Mucor circinelloides UCP0001. A central rotational composite design was applied to statistical validation of the production. The emulsifying properties, stability under extreme conditions, its toxicity character, and the characterization of the bioemulsifier were determined. The best condition for biomolecule synthesis occurred in the assay 2 containing 4% of corn steep liquor and 3% waste soybean oil and exhibited 100% emulsification index for canola oil and petroleum, as well as excellent emulsifying activity for canola oil and burned engine oil. The nutritional factors studied showed statistical relevance, since all linear, quadratic effects and their interactions were significant. The bioemulsifier showed 2.69 g/L yield and the chemical character of the molecule structure was identified by FT-IR (Fourier Transform Infrared) spectroscopy. The bioemulsifier showed no toxicity to Artemia salina and Chlorella vulgaris. Stable emulsions were obtained under extreme conditions of temperature, pH, and salinity. These findings contribute to understanding of the relationship between production, physical properties, chemical composition, and stability of bioemulsifier for their potential applications in biotechnology, such as bioremediation of hydrocarbon-contaminated soil and water.

Assessing interactions, predicting function, and increasing degradation potential of a PAH-degrading bacterial consortium by effect of an inoculant strain

A natural phenanthrene-degrading consortium CON was inoculated with an exogenous strain Sphingobium sp. (ex Sp. paucimobilis) 20006FA yielding the consortium called I-CON, in order to study ecological interactions into the bacterial community. DGGE and proteomic profiles and analyses by HTS (High-Throughput Sequencing) technologies demonstrated inoculant establishment and changes on CON composition. Inoculation increased degradation efficiency in I-CON and prevented intermediate HNA accumulation. This could be explained not only by the inoculation, but also by enrichment in Achromobacter genus at expense of a decrease in Klebsiella genus. After inoculation, cooperation between Sphingobium and Achromobacter genera were improved, thereby, some competition could have been generated, and as a consequence, species in minor proportion (cheaters), as Inquilinus sp. and Luteibacter sp., were not detected. Sequences of Sphingobium (corresponding to the inoculated strain) did not vary. PICRUSt predicted a network with bacterial phylotypes connected with enzymes, showing functional redundancy in the phenanthrene pathway, with exception of the first enzymes biphenyl-2,3-diol 1,2-dioxygenase and protocatechuate 4,5-dioxygenase that were only encoded in Sphingobium sp. This is the first report where a natural consortium that has been characterized by HTS technologies is inoculated with an exogenous strain in order to study competitiveness and interactions.

Occurrence of non-toxic bioemulsifiers during polyhydroxyalkanoate production by Pseudomonas strains valorizing crude glycerol by-product

While screening for polyhydroxyalkanoate (PHA) producing strains, using glycerol rich by-product as carbon source, it was observed that extracellular polymers were also secreted into the culture broth. The scope of this study was to characterize both intracellular and extracellular polymers, produced by Pseudomonas putida NRRL B-14875 and Pseudomonas chlororaphis DSM 50083, mostly focusing on those novel extracellular polymers. It was found that they fall into the class of bioemulsifiers (BE), as they showed excellent emulsion stability against different hydrocarbons/oils at various pH conditions, temperature and salinity concentrations. Cytotoxicity tests revealed that BE produced by P. chlororaphis inhibited the growth of highly pigmented human melanoma cells (MNT-1) by 50% at concentrations between 150 and 200 μg/mL, while no effect was observed on normal skin primary keratinocytes and melanocytes. This is the first study reporting mcl-PHA production by P. putida NRRL B-14785 and bioemulsifier production from both P. putida and P. chlororaphis strains.

Role of hemoglobin in hemoglobin-based remediation of the crude oil-contaminated soil

This study investigated the changes in the indigenous microbial community structure with hemoglobin (Hb) application to determine the role of Hb in Hb-based remediation of crude oil-contaminated soil. The phylogenetic diversity of the bacterial community showed that the Hb addition selected surfactants-producing species, thereby, promoting TPH degradation. The significant increase in the CO₂ generation, which can be related to the increase in the bacterial abundance inferred from the 16S rRNA gene copy number, supports the enhanced TPH degradation with Hb application. The similar residual TPH concentrations in the presence of only hydrogen peroxide (H₂O₂) and both Hb and H₂O₂ suggested that the role of Hb as a catalyst was not as significant as the role of Hb as a nutrient. Also, in the presence of H₂O₂, a greater recovery of the microbial community structure was observed with the double Hb injection than the single Hb injection. Overall, this study shows that the Hb-based remediation strategies via microbial metabolism can be successfully applied to remediate the crude-oil contaminated Kuwaiti soil.

Hydrocarbon degradation abilities of psychrotolerant Bacillus strains

Biodegradation requires identification of hydrocarbon degrading microbes and the investigation of psychrotolerant hydrocarbon degrading microbes is essential for successful biodegradation in cold seawater. In the present study, a total of 597 Bacillus isolates were screened to select psychrotolerant strains and 134 isolates were established as psychrotolerant on the basis of their ability to grow at 7 °C. Hydrocarbon degradation capacities of these 134 psychrotolerant isolate were initially investigated on agar medium containing different hydrocarbons (naphthalene, n-hexadecane, mineral oil) and 47 positive isolates were grown in broth medium containing hydrocarbons at 20 °C under static culture. Bacterial growth was estimated in terms of viable cell count (cfu ml-1). Isolates showing the best growth in static culture were further grown in presence of crude oil under shaking culture and viable cell count was observed between 8.3 × 105-7.4 × 108 cfu ml-1. In the final step, polycyclic aromatic hydrocarbon (PAH) (chrysene and naphthalene) degradation yield of two most potent isolates was determined by GC-MS along with the measurement of pH, biomass and emulsification activities. Results showed that isolates Ege B.6.2i and Ege B.1.4Ka have shown 60% and 36% chrysene degradation yield, respectively, while 33% and 55% naphthalene degradation yield, respectively, with emulsification activities ranges between 33-50%. These isolates can be used to remove hydrocarbon contamination from different environments, particularly in cold regions.

A novel bioemulsifier produced by Exiguobacterium sp. strain N4-1P isolated from petroleum hydrocarbon contaminated coastal sediment

In this study,ExiguobacteriumN4-1P is reported as a bioemulsifier producer for the first time.

Isolation, identification, and crude oil degradation characteristics of a high-temperature, hydrocarbon-degrading strain

In this work, a hydrocarbon-degrading bacterium Y-1 isolated from petroleum contaminated soil in the Dagang Oilfield was investigated for its potential effect in biodegradation of crude oil. According to the analysis of 16S rRNA sequences, strain Y-1 was identified as Bacillus licheniformis. The growth parameters such as pH, temperature, and salinity were optimised and 60.2% degradation of crude oil removal was observed in 5days. The strain Y-1 showed strong tolerance to high salinity, alkalinity, and temperature. Emplastic produced by strain Y-1 at high temperatures could be applied as biosurfactant. Gas chromatography analysis demonstrated that the strain Y-1 efficiently degraded different alkanes from crude oil, and the emplastic produced by strain Y-1 promoted the degradation rates of long-chain alkanes when the temperature increased to 55°C. Therefore, strain Y-1 would play an important role in the area of crude oil contaminant bioremediation even in some extreme conditions.

Optimization and characterization of biosurfactant production from marine Vibrio sp. strain 3B-2

A biosurfactant-producing bacterium, designated 3B-2, was isolated from marine sediment and identified as Vibrio sp. by 16S rRNA gene sequencing. The culture medium composition was optimized to increase the capability of 3B-2 for producing biosurfactant. The produced biosurfactant was characterized in terms of protein concentration, surface tension, and oil-displacement efficiency. The optimal medium for biosurfactant production contained: 0.5% lactose, 1.1% yeast extract, 2% sodium chloride, and 0.1% disodium hydrogen phosphate. Under optimal conditions (28°C), the surface tension of crude biosurfactant could be reduced to 41 from 71.5 mN/m (water), while its protein concentration was increased to up to 6.5 g/L and the oil displacement efficiency was improved dramatically at 6.5 cm. Two glycoprotein fractions with the molecular masses of 22 and 40 kDa were purified from the biosurfactant, which held great potential for applications in microbial enhanced oil recovery and bioremediation.

High molecular weight bioemulsifiers, main properties and potential environmental and biomedical applications

High molecular weight bioemulsifiers are amphipathic polysaccharides, proteins, lipopolysaccharides, lipoproteins, or complex mixtures of these biopolymers, produced by a wide variety of microorganisms. They are characterized by highly structural diversity and have the ability to decrease the surface and interfacial tension at the surface and interface respectively and/or emulsify hydrophobic compounds. Emulsan, fatty acids, phospholipids, neutral lipids, exopolysaccharides, vesicles and fimbriae are among the most popular high molecular weight bioemulsifiers. They have great physic-chemical properties like tolerance to extreme conditions of pH, temperature and salinity, low toxicity and biodegradability. Owing their emulsion forming and breaking capacities, solubilization, mobilization and dispersion activities and their viscosity reduction activity; they possess great environmental application as enhancer of hydrocarbon biodegradation and for microbial enhanced oil recovery. Besides, they are applied in biomedical fields for their antimicrobial and anti-adhesive activities and involvement in immune responses.

Genome Sequence of Enterobacter cancerogenus YZ1

Enterobacter cancerogenus is usually known as an opportunistic human pathogen. Recently, it has attracted great attention for its capability to produce bioemulsifier, degrade xenobiotics, and resist alkalis and antibiotics. Here we report the complete genome of Enterobacter cancerogenus YZ1, isolated from a bran-feeding Coleoptera insect’s frass.

Study of the interactive effect of temperature and pH on exopolysaccharide production by Enterobacter A47 using multivariate statistical analysis

Enterobacter A47 synthesizes fucose-containing exopolysaccharides (EPS). Maximum EPS production (>7.00 g L(-1)) was obtained for temperature and pH within 25-35°C and 6.0-8.0, respectively. Under these conditions, the polymers contained over 30% fucose. Glucose, galactose, and glucuronic acid contents were about 28%, 25%, and 10%, respectively, and the total acyl groups content was about 20 wt.%. The average molecular weight (Mw) was around 4.0 × 10(6). Outside the optimal temperature and pH ranges, fucose, galactose and glucuronic acid, and the total acyl group contents were reduced, while the glucose content increased, new monomers (rhamnose and glucosamine) were detected, and the Mw increased to ≥ 1.10 × 10(7). This study revealed the ability of Enterobacter A47 to synthesize different heteropolysaccharides as a function of pH and temperature, a feature that can be exploited to obtain tailored polymer composition. Moreover, the production of high fucose content EPS was stable for wide pH and temperature ranges, which is important for the envisaged industrial development of the bioprocess.