Biodegradation of Crude Oil by a Newly Isolated Strain Rhodococcus sp. JZX-01

A highly efficient oil-degrading bacteria JZX-01 was isolated from the oil-contaminated soil of the seacoast near the Boxi Offshore Oil Field of China. Morphological, physiological, and 16S rDNA gene sequence analyses indicated that JZX-01 was assigned to the genus Rhodococcus sp. This strain decomposed 65.27?±?5.63 % of the crude oil in 9 days. Gas chromatography–mass spectrometry analysis showed that even the long-chain hydrocarbons (C31–C38) and branched alkanes (pristine and phytane), which were regarded as the stubborn ones, could be degraded. Further study showed that the bacteria still has good oil degradation ability at low temperatures as well as under high salt conditions. Moreover, JZX-01 was found to have a biosurfactant-producing capacity, which significantly favors the surface tension reduction and crude oil degradation. The promising isolated strain Rhodococcus sp. JZX-01 could be further used for the bioremediation of oil-polluted soil or seawater in a wide range of temperatures and high salt conditions.     

Enhanced Biodegradation of Alkane Hydrocarbons and Crude Oil by Mixed Strains and Bacterial Community Analysis

In this study, two strains, Acinetobacter sp. XM-02 and Pseudomonas sp. XM-01, were isolated from soil samples polluted by crude oil at Bohai offshore. The former one could degrade alkane hydrocarbons (crude oil and diesel, 1:4 (v/v)) and crude oil efficiently; the latter one failed to grow on alkane hydrocarbons but could produce rhamnolipid (a biosurfactant) with glycerol as sole carbon source. Compared with pure culture, mixed culture of the two strains showed higher capability in degrading alkane hydrocarbons and crude oil of which degradation rate were increased from 89.35 and 74.32?±?4.09 to 97.41 and 87.29?±?2.41 %, respectively. In the mixed culture, Acinetobacter sp. XM-02 grew fast with sufficient carbon source and produced intermediates which were subsequently utilized for the growth of Pseudomonas sp. XM-01 and then, rhamnolipid was produced by Pseudomonas sp. XM-01. Till the end of the process, Acinetobacter sp. XM-02 was inhibited by the rapid growth of Pseudomonas sp. XM-01. In addition, alkane hydrocarbon degradation rate of the mixed culture increased by 8.06 to 97.41 % compared with 87.29 % of the pure culture. The surface tension of medium dropping from 73.2?×?10^?3 to 28.6?×?10^?3 N/m. Based on newly found cooperation between the degrader and the coworking strain, rational investigations and optimal strategies to alkane hydrocarbons biodegradation were utilized for enhancing crude oil biodegradation.     

Induced production of cytochalasans in co-culture of marine fungus Aspergillus flavipes and actinomycete Streptomyces sp.

Secondary metabolites profiles of co-culture of Aspergillus flavipes and Streptomyces sp. that isolated from the same habitat showed an induced production of a series of cytochalasans (five aspochalasins and rosellichalasin, determined by MS and NMR analysis). These cytochalasans were found to be produced by A. flavipes in LC–MS comparison analysis, and biological activity assays revealed that they were able to cause cytotoxic effects against Streptomyces sp. within a wide range of concentrations without causing any effect to the producer A. flavipes, which favoured the producer in competition. Further induction mechanism study applying membrane-separated culture and morphology study with scanning electron microscopy (SEM) suggested that the successful induction of active secondary metabolites required microbial physical contact.     

Role of Brucella sp. and Gallionella sp. in oil degradation and corrosion

Microbiologically influenced corrosion is responsible for most of the internal corrosion in oil transmission pipelines and storage tanks. In the present study, the role of bacteria on oil degradation and its influence on corrosion have been studied. Two systems (biotic and abiotic) with and without inorganic content and bacteria were employed for studying degradation and corrosion. The aerobic heterotrophic bacterial population (HB) was found to be higher in the presence of inorganic medium than its absence. The oil degradation by microbes was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The corrosion studies were carried out by gravimetric method. It was found that Gallionella sp. degraded aliphatic protons CH₂CH₂ to OCH₂ whereas Brucella sp. converted only aromatic ring to aliphatic protons. The following inferences have been made from this study: (a) inorganic contents in contaminated water determine the oil degradation in storage tanks and transporting pipelines; (b) the degraded product may adsorb on pipeline, which would enhance the rate of microbial corrosion.     

Purification and characterization of a biosurfactant produced by Pseudomonas sp. G11 by asymmetrical flow field-flow fractionation (AsFlFFF)

Three hundred and thirty two bacterial colonies were isolated from soil contaminated by an oil spill. All the bacteria were cultured in a liquid medium individually, and the surface tensions of the media were compared. The bacterium whose culture medium had the lowest surface tension was identified as Pseudomonas sp. G11. A biosurfactant was produced by cultivation of the Pseudomonas sp. G11 in the LB media. For extraction of the biosurfactant, two solvent systems were used (n-hexane and a 2:1 (v/v) mixture of chloroform/MeOH), and the results were compared. Various experimental conditions (solvent composition, flow rate, etc.) were tested to optimize the analysis of the biosurfactant by asymmetrical flow field-flow fractionation (AsFlFFF). The biosurfactant was successfully separated from the culture medium by AsFlFFF when pure water was used as the carrier. From the retention data, the hydrodynamic diameter (d _H) and molecular weight (M) of the biosurfactant were determined by AsFlFFF. The molecular weight was determined by using pullulans as the calibration standards. The d _H and M were 49 nm and 2.3 × 10⁵ Da when extracted with n-hexane, and 39 nm and 1.13 × 10⁵ Da when extracted with the 2:1 mixture of chloroform/MeOH, respectively. Figure Separation of biosurfactant from its culture medium by flow FFF     

Biodegradation Potential of Bacillus sp. PAH-2 on PAHs for Oil-Contaminated Seawater

Microbial degradation is a useful tool for inhibiting or preventing polycyclic aromatic hydrocarbons (PAHs) widely distributed in marine environment after oil spill accidents. This study aimed to evaluate the potential and diversity of bacteria Bacillus sp. PAH-2 on Benzo (a) anthracene (BaA), Pyrene (Pyr), and Benzo (a) pyrene (BaP), their composite system, aromatic components system, and crude oil. The seven-day degradation rates against BaA, Pyr, and BaP were 20.6%, 12.83%, and 17.49%, respectively. Further degradation study of aromatic components demonstrated PAH-2 had a high degradation rate of substances with poor stability of molecular structure. In addition, the degradation of PAHs in crude oil suggested PAH-2 not only made good use of PAHs in such a more complex structure of pollutants but the saturated hydrocarbons in the crude oil also showed a good application potential.     

Water treatment with a shungite sorbent and biosorbents on its base

Physicochemical and sorption properties of a nonactivated shungite sorbent were studied. The immobilization of yeast cells of Kluveramyces sp. (strain 11 K) and Candida sp. (strain 10 K) and cells of oil-oxidizing bacterial cultures Mycobacterium sp. (strain 119–3 GM) and Pseudomonas sp. (strain 51 K) on this sorbent was examined. A comparative analysis of the accumulation of heavy metal ions and degradation of oil by free and immobilized cells of these microorganisms was carried out. The efficiency of application of biosorbents produced on the basis of the shungite support in water treatment to remove heavy metals and oil was studied.     

Production of bacterial cellulose by Gluconacetobacter sp. RKY5 isolated from persimmon vinegar

The optimum fermentation medium for the production of bacterial cellulose (BC) by a newly isolated Gluconacetobacter sp. RKY5 was investigated. The optimized medium composition for cellulose production was determined to be 15 g/L glycerol, 8 g/L yeast extract, 3 g/L K₂HPO₄, and 3 g/L acetic acid. Under these optimized culture medium, Gluconacetobacter sp. RKY5 produced 5.63 g/L of BC after 144 h of shaken culture, although 4.59 g/L of BC was produced after 144 h of static culture. The amount of BC produced by Gluconacetobacter sp. RKY5 was more than 2 times in the optimized medium found in this study than in a standard Hestrin and Shramm medium, which was generally used for the cultivation of BC-producing organisms.     

Oil from the Tropical Marine Benthic-Diatom Navicula sp.

The potential of the tropical marine benthic-diatom Navicula sp. for biodiesel feedstock was investigated. Growth profiles were analyzed by changing nutrient compositions in three different media (Walne, plain seawater, and modified seawater) and irradiance intensities. Navicula sp. cells showed significant growth in Walne and modified seawater medium but not in plain seawater medium. The microalgae grew well in a pH range of 7.8?C8.4, and the cells were very sensitive to the intensity of direct sunlight exposure. The average cell concentration obtained from the cultures in plain seawater, Walne, and modified seawater media at the beginning of the stationary phase was 0.70, 2.17, and 2.54?g/L, respectively. Electron spray ionization-ion trap-mass spectrometry showed that the triacylglycerols of the algae oil were identified as POP (palmitic-oleic-palmitic), POO (palmitic-oleic-oleic), and OOLn (oleic-oleic-linoleic). The oil productivity of Navicula sp. cultivated in Walne and modified seawater media was 90 and 124???L?L^?1 culture d^?1. The Navicula sp. biodiesel exhibited a kinematic viscosity of 1.299?mm²/s, density of 0.8347?g/mL, and internal energy of 0.90?kJ/mL.     

Application of Co-Culture Technology to Enhance Protease Production by Two Halophilic Bacteria,Marinirhabdus sp. and Marinobacter hydrocarbonoclasticus

Although axenic microbial cultures form the basis of many large successful industrial biotechnologies, the production of single commercial microbial strains for use in large environmental biotechnologies such as wastewater treatment has proved less successful. This study aimed to evaluate the potential of the co-culture of two halophilic bacteria, Marinirhabdus sp. and Marinobacter hydrocarbonoclasticus for enhanced protease activity. The co-culture was significantly more productive than monoculture (1.6–2.0 times more growth), with Marinobacter hydrocarbonoclasticus being predominant (64%). In terms of protease activity, enhanced total activity (1.8–2.4 times) was observed in the co-culture. Importantly, protease activity in the co-culture was found to remain active over a much broader range of environmental conditions (temperature 25 °C to 60 °C, pH 4–12, and 10–30% salinity, respectively). This study confirms that the co-culturing of halophilic bacteria represents an economical approach as it resulted in both increased biomass and protease production, the latter which showed activity over arange of environmental conditions.     

Enhancement of Paenibacillus sp. D9 Lipopeptide Biosurfactant Production Through the Optimization of Medium Composition and Its Application for Biodegradation of Hydrophobic Pollutants

Interests in biosurfactant in industrial and environmental applications have increased considerably in recent years, owing to their potential benefits over synthetic counterparts. The present study aimed at analyzing the stability and oil removal efficiency of a new lipopeptide biosurfactant produced by Paenibacillus sp. D9 and its feasibility of its use in biotechnological applications. Paenibacillus sp. D9 was evaluated for optimal growth conditions and improved production yield of lipopeptide biosurfactant with variations in different substrate parameters such as carbon (C), nitrogen (N), C:N: ratio, metal supplements, pH, and temperature. Enhanced biosurfactant production was observed when using diesel fuel and ammonium sulfate as carbon and nitrogen source respectively. The maximum biosurfactant yield of 4.11 g/L by Paenibacillus sp. D9 occurred at a C/N ratio of 3:1, at pH 7.0, 30 °C, 4.0 mM MgSO₄, and 1.5% inoculum size. The D9 biosurfactant was found to retain surface-active properties under the extreme conditions such as high thermal, acidic, alkaline, and salt concentration. The ability to emulsify further emphasizes its potential usage in biotechnological application. Additionally, the lipopeptide biosurfactant exhibited good performance in the degradation of highly toxic substances when compared with chemical surfactant, which proposes its probable application in biodegradation, microbial-enhanced oil recovery or bioremediation. Furthermore, the biosurfactants were effective in a test to stimulate the solubilization of hydrophobic pollutants in both liquid environments removing 49.1 to 65.1% diesel fuel including hydrophobic pollutants. The study highlights the usefulness of optimization of culture parameters and their effects on biosurfactant production, high stability, improved desorption, and solubilization of hydrophobic pollutants.

     

Microbial desulfurization of waste latex rubber with Alicyclobacillus sp.

A microbe with desulfurizing capability, Alicyclobacillus sp., was selected to recycle waste latex rubber (WLR). The growth characteristics of the microorganism and the technical conditions in the co-culture desulfurization process were studied. The desulfurization effect of Alicyclobacillus sp. on the WLR was characterized, and the mechanism for the microbial desulfurization of WLR was tentatively explored. The results showed that adding 5% (w/v) WLR into medium had little effect on the growth of Alicyclobacillus sp. The surfactant polysorbate 80 (Tween 80) had a toxic effect on Alicyclobacillus sp., but the growth of the microbe was vigorous if the proper technique was used: the mixing of WLR with Tween 80, followed by the addition of the mixture into the culture media. With the increase of desulfurization time, the swelling value of desulfurizated waste latex rubber (DWLR) increased, but the crosslink density decreased. After co-culture desulfurization for 8–10 days, a DWLR with good desulfurization effect was obtained. The mechanical properties of natural rubber (NR)/DWLR composite improved significantly over those of NR/WLR composite. XPS and FTIR results revealed that Alicyclobacillus sp. could break the crosslinked sulfur bonds and oxidize them to sulfones groups. The increase of O element content on the surface of DWLR was confirmed by water contact angle measurements. The relationship between the crosslink density and sol fraction of DWLR with different desulfurization times agreed with the Horikx equation, an indication that the microorganisms could break the crosslinked sulfur bonds on the surface of WLR, but leaving the main chains intact.     

Heavy Vacuum Gas Oil Upregulates the Rhamnosyltransferases and Quorum Sensing Cascades of Rhamnolipids Biosynthesis in Pseudomonas sp. AK6U

We followed a comparative approach to investigate how heavy vacuum gas oil (HVGO) affects the expression of genes involved in biosurfactants biosynthesis and the composition of the rhamnolipid congeners in Pseudomonas sp. AK6U. HVGO stimulated biosurfactants production as indicated by the lower surface tension (26 mN/m) and higher yield (7.8 g/L) compared to a glucose culture (49.7 mN/m, 0.305 g/L). Quantitative real-time PCR showed that the biosurfactants production genes rhlA and rhlB were strongly upregulated in the HVGO culture during the early and late exponential growth phases. To the contrary, the rhamnose biosynthesis genes algC, rmlA and rmlC were downregulated in the HVGO culture. Genes of the quorum sensing systems which regulate biosurfactants biosynthesis exhibited a hierarchical expression profile. The lasI gene was strongly upregulated (20-fold) in the HVGO culture during the early log phase, whereas both rhlI and pqsE were upregulated during the late log phase. Rhamnolipid congener analysis using high-performance liquid chromatography-mass spectrometry revealed a much higher proportion (up to 69%) of the high-molecularweight homologue Rha–Rha–C₁₀–C₁₀ in the HVGO culture. The results shed light on the temporal and carbon source-mediated shifts in rhamonlipids’ composition and regulation of biosynthesis which can be potentially exploited to produce different rhamnolipid formulations tailored for specific applications.     

Screening of soil bacteria for production of biocleaner

Soil bacteria were studied for the production of biodegradable cleaning agents. Among 86 bacterial strains resistant to liquid paraffin, 58 showed hemolytic activity. These strains were cultured, and the supernatant of culture broths was evaluated for cleaning activity against a dirty porcelain tile. Potent activity was exhibited in 18 strains. The lowest value of surface tension was obtained from Bacillus sp. NKB03 suggesting the presence of a biosurfactant. Aeromonas sp. NKB26c and Bacillus cereus NKB46b exhibited enzymatic cleaning activity. A cleaning efficiency of 82% was achieved when using a mixture of supernatants from culture broths of Bacillus sp. NKB03 and Aeromonas sp. NKB26c in synthetic minimal media. The cleaning efficiency using this mixture was higher than that of sodium dodecyl sulfate. These results suggest that a mixture of supernatants from culture broths of Bacillus sp. NKB03 and Aeromonas sp. NKB26c has potential for commercial use as a biocleaner.     

Taxonomic Identification and Use of Free and Entrapped Cells of a New <Emphasis Type="Italic">Mycobacterium</Emphasis> sp., Strain Spyr1 for Degradation of Polycyclic Aromatic Hydrocarbons (PAHs)

A polycyclic aromatic hydrocarbon (PAH)-degrading bacterial strain Spyr1 was isolated from Greek creosote polluted soil by an enrichment method using pyrene as sole carbon and energy source. Spyr1 was identified as Mycobacterium sp. based on 16S rDNA analysis and it was capable of degrading pyrene, fluoranthene, fluorene, anthracene, and acenaphthene. The effect of entrapment in glass beads and alginate/starch mixtures on the survival and pyrene degradation ability of Spyr1 cells in liquid suspensions and soil microcosms was tested and compared with that of freely suspended cells. In general, free cells showed higher degradation of pyrene and other PAH than immobilized cells. However, immobilized cells could better tolerate PAH and they maintained their viability and PAH degradation capability for at least 1 year after storage at 4 °C. Entrapped cells in glass beads exhibited better pyrene biodegradation performance than alginate/starch entrapped cells in liquid suspensions and could be used effectively for at least ten repeated cycles. Alginate/starch entrapped cells exhibited better yields than glass beads entrapped cells for removing pyrene as well as mixtures of PAH in soil microcosms.     

The phenol efficient degradation using co-culture coupled with enhanced electricity generation capability

The co-culture of strain Citrobacter sp. RDC and Geobacter sulfurreducens PCA was used in this study and it was found that the co-culture using 200 mg/L phenol as carbon source exhibited higher maximum current density than using the single strain RDC and G. sulfurreducens PCA, respectively. Meanwhile, the co-culture was used to generate electricity by degrading phenol with the current density of 699.07 μA/cm² by using 200 mg/L phenol as the sole carbon source, which was higher than that only using G. sulfurreducens PCA (236.20 μA/cm²). Especially, the degradation efficiency of 200 mg/L phenol by co-culture can reach 55.16 % within 36 h being 4.16-fold higher than the single strain G. sulfurreducens PCA. Furthermore, the component ratio of two strains was optimized for increasing electricity generation using 500 mg/L phenol as carbon source. The maximum current density was 501.54 μA/cm² under the ratio of 3 : 1 for strain RDC to G. sulfurreducens PCA. These results highlight that phenol is good carbon source for co-culture to produce electricity. The co-culture system provides a promising application pathway for phenol degradation treatment coupled with electricity generation in the future.     

Comparison of denitrification between Paracoccus sp. and Diaphorobacter sp

Denitrification was compared between Paracoccus sp. and Diaphorobacter sp. in this study, both of which were isolated from activated sludge of a denitrifying reactor. Denitrification of both isolates showed contrasting patterns, where Diaphorobacter sp. showed accumulation of nitrite in the medium while Paracoccus sp. showed no accumulation. The nitrate reduction rate was 1.5 times more than the nitrite reduction in Diaphorobacter sp., as analyzed by the resting state denitrification kinetics. Increasing the nitrate concentration in the medium increased the nitrite accumulation in Diaphorobacter sp., but not in Paracoccus sp., indicating a branched electron transfer during denitrification. Diaphorobacter sp. was unable to denitrify efficiently at high nitrate concentrations from 1 M, but Paracoccus sp. could denitrify even up to 2 M nitrate. Paracoccus sp. was found to be an efficient denitrifier with insignificant amounts of nitrite accumulation, and it could also denitrify high amounts of nitrate up to 2 M. Efficient denitrification without accumulation of intermediates like nitrite is desirable in the removal of high nitrates from wastewaters. Paracoccus sp. is shown to suffice this demand and could be a potential organism to remove high nitrates effectively.     

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.     

Production of Biodegradable Polymer from Agro-Wastes in Alcaligenes sp. and Pseudomonas sp.

The present study was aimed to evaluate the suitability of agro-wastes and crude vegetable oils for the cost-effective production of poly-β-hydroxybutyrate (PHB), to evaluate growth kinetics and PHB production in Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1 with these carbon substrates and to study the biodegradation of PHB accumulated by these cultures. Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1 accumulates higher amounts of PHB corn (79.90% of dry cell mass) and rice straw (66.22% of dry cell mass) medium respectively. The kinetic model suggests that the Pseudomonas sp. RZS1 follows the Monod model more closely than A. faecalis RZS4. Both the cultures degrade their PHB extract under the influence of PHB depolymerase. Corn waste and rice straw appear as the best and cost-effective substrates for the sustainable production of PHB from Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1. The biopolymer accumulated by these organisms is biodegradable in nature. The agro-wastes and crude vegetable oils are good and low-cost sources of nutrients for the growth and production of PHB and other metabolites. Their use would lower the production cost of PHB and the low-cost production will reduce the sailing price of PHB-based products. This would promote the large-scale commercialization and popularization of PHB as an ecofriendly bioplastic/biopolymer.     

Effect of Fusarium oxysporum f. sp. lycopersici on the degradation of humic acid associated with Cu, Pb, and Ni: an in vitro study

The intent of this work was to gain further insight on the fungus-assisted degradation/solubilization of humic acid and the related changes in metal-binding profiles. In the experimental design, Aldrich reagent humic acid (HA) or HA enriched with Cu, Pb, and Ni (HA(Me)) was added to Fusarium oxysporum f. sp. lycopersici cultures in vitro. The cultures were supplied by different carbon- and nitrogen-containing nutrients (glucose, Glc, or glutamate, Glu and ammonium, NH₄⁺, or nitrate, NO₃⁻, ions, respectively) in order to examine their possible effect on HA and HA(Me) decomposition. During the first 48 h of fungus growth, gradual acidification to pH 2 was observed in medium containing Glc + NH₄⁺, while for other cultures, alkalinization to pH 9 occurred and then, the above conditions were stable up to at least 200 h. Size exclusion chromatography (SEC) with UV/Vis detection showed progressive degradation and solubilization of both HA and HA(Me) with the increasing time of fungus growth. However, the molecular mass distributions of HA-related soluble species were different in the presence of metals (HA(Me)) as referred to HA and were also influenced by the composition of growth medium. The solubilization of Pb, Cu, and Ni and their association with HA molecular mass fractions were studied using inductively coupled plasma mass spectrometry (ICP-MS) detection. Under acidic conditions, relatively high concentrations of low-molecular-mass metallic species were found in culture supernatants, while in alkaline media, metal solubilization was generally poorer. In contrast to low pH culture, SEC-ICP-MS results obtained in alkaline supernatants indicated metal binding to degradation products of humic substances of MM > 5 kDa. In summary, the results of this study suggest that fungus-assisted degradation of HA and HA(Me) might be controlled using appropriate N- and C- sources required for fungus growth, which in turn would affect molecular mass distribution of soluble metallic species thus potentially influencing their actual bioaccessibility. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.