Diesel and Kerosene Degradation by Pseudomonas desmolyticum NCIM 2112 and Nocardia hydrocarbonoxydans NCIM 2386

Reconstruction of microbiome and functionality accelerated crude oil biodegradation of 2,4-DCP-oil-contaminated soil systems using composite microbial agent B-Cl

Biodegradation is one of the safest and most economical methods for the elimination of toxic chlorophenols and crude oil from the environment. In this study, aerobic degradation of the aforementioned compounds by composite microbial agent B-Cl, which consisted of Bacillus B1 and B2 in a 3:2 ratio, was analyzed. The biodegradation mechanism of B-Cl was assessed based on whole genome sequencing, Fourier transform infrared spectroscopy and gas chromatographic analyses. B-Cl was most effective at reducing Cl^- concentrations (65.17%) and crude oil biodegradation (59.18%) at 7 d, which was when the content of alkanes ≤ C₃₀ showed the greatest decrease. Furthermore, adding B-Cl solution to soil significantly decreased the 2,4-DCP and oil content to below the detection limit and by 80.68%, respectively, and reconstructed of the soil microbial into a system containing more CPs-degrading (exaA, frmA, L-2-HAD, dehH, ALDH, catABE), aromatic compounds-degrading (pcaGH, catAE, benA-xylX, paaHF) and alkane- and fatty acid-degrading (alkB, atoB, fadANJ) microorganisms. Moreover, the presence of 2,4-DCP was the main hinder of the observed effects. This study demonstrates the importance of adding B-Cl solution to determine the interplay of CPs with microbes and accelerating oil degradation, which can be used for in-situ bioremediation of CPs and oil-contaminated soil.

Degradation characteristics of crude oil by a consortium of bacteria in the existence of chlorophenol

In order to enhance the degradation effect of microorganisms on crude oil in the existence of chlorophenol compounds, oil-degrading bacteria C4 (Alcaligenes faecails), C5 (Bacillus sp.) and 2,4-dichlorophenol (2,4-DCP) degrading bacteria L3 (Bacillus marisflavi), L4 (Bacillus aquimaris) were isolated to construct a highly efficient consortium named (C4C5 + L3L4). When the compound bacteria agent combination by V_C4: V_C5: V_L3: V_L4 = 1:2:2:1, the crude oil degradation efficiency of 7 days was stable at 50.63% ~ 55.43% under different conditions. Degradation mechanism was analyzed by FTIR, GC-MS and IC technology and the following conclusions showed that in the system of adding consortium (C4C5 + L3L4), the heavy components were converted into saturated and unsaturated components. The bacterial consortium could first degrade medium and long chain alkanes into short chain hydrocarbons and then further degrade. And the dechlorination efficiency of 2,4-DCP in the degradation system reached 73.83%. The results suggested that the potential applicability and effectiveness of the selected bacteria consortium for the remediation of oil-contaminated water or soil with the existence of chlorophenol compound.

Biodegradation of the aromatic fraction from petroleum diesel fuel by Oerskovia sp. followed by comprehensive GC×GC-TOF MS

Polycyclic aromatic hydrocarbons (PAHs) from petroleum and fossil fuels are one of the most dominant pollutants in the environment. Since aromatic fraction from petroleum diesel fuel is mainly composed of PAHs, it is important to discover new microorganisms that can biodegrade these compounds. This article describes the biodegradation of the aromatic fraction separated from petroleum diesel fuel using the strain Oerskovia sp. CHP-ZH25 isolated from petroleum oil-contaminated soil. The biodegradation was monitored by gravimetry and GC × GC-TOF MS. An innovative method was applied to visualize degraded compounds in the data provided by a GC × GC-TOF MS. It was shown that Oerskovia sp. CHP-ZH25 degraded 77.4% based on gravimetric analysis within 30 days. Average rate of degradation was 14.4 mg/L/day, 10.5 mg/l/day and 4.0 mg/l/day from 0 to 10 day, 10-20 and 20-30 day, respectively. The order of PAH degradation based on decrease in peak volume after 30 days of incubation was as follows: dibenzothiophene derivatives > benzo[b]thiophene derivatives > naphthalene derivatives > acenaphthene derivatives > acenaphthylene/biphenyl derivatives > fluorene derivatives > phenanthrene/anthracene derivatives. Here we demonstrated that Oerskovia sp. CHP-ZH25 could potentially be a suitable candidate for use in bioremediation of environments polluted with different PAHs.

Diesel oil removal by Serratia sp. W4-01 immobilized in chitosan-activated carbon beads

Serratia sp. W4-01 was immobilized in chitosan-activated carbon beads and used for diesel oil removal. The type and concentration of chitosan, activated carbon content, and bead diameter were investigated as factors affecting diesel oil removal. The results showed that 2% (w/v) squid pen chitosan beads modified with 1% activated carbon (w/v) and with a 3-mm diameter had a good spherical shape and strength as well as diesel oil removal capability. The immobilized W4-01 cells removed more than 40% of diesel oil after 7 days when the initial diesel oil concentration was 100 to 400 mg L^-1, whereas 29-36% of diesel oil was removed after 14 days when the initial concentration was 800 to 1000 mg L^-1. Additionally, the immobilized cells maintained the ability to remove diesel oil over a pH range of 5-11. The addition of a biosurfactant increased the diesel oil removal from 62 to 75%. The reusability tests revealed that the ability of immobilized cells to remove diesel oil was enhanced after reuse, and 50-90% of diesel oil was removed during 2 to 12 reuse cycles. The stability and survival of W4-01 cells was confirmed by scanning electron microscopy and confocal laser scanning microscopy. The results of this study showed the potential use of W4-01 cells immobilized in chitosan-activated carbon beads for future applications in remediating diesel contamination.

Characterization of the genome of a Nocardia strain isolated from soils in the Qinghai-Tibetan Plateau that specifically degrades crude oil and of this biodegradation

A strain of Nocardia isolated from crude oil-contaminated soils in the Qinghai-Tibetan Plateau degrades nearly all components of crude oil. This strain was identified as Nocardia soli Y48, and its growth conditions were determined. Complete genome sequencing showed that N. soli Y48 has a 7.3 Mb genome and many genes responsible for hydrocarbon degradation, biosurfactant synthesis, emulsification and other hydrocarbon degradation-related metabolisms. Analysis of the clusters of orthologous groups (COGs) and genomic islands (GIs) revealed that Y48 has undergone significant gene transfer events to adapt to changing environmental conditions (crude oil contamination). The structural features of the genome might provide a competitive edge for the survival of N. soli Y48 in oil-polluted environments and reflect the adaptation of coexisting bacteria to distinct nutritional niches.

Phytoremediation of textile dyes and effluents: Current scenario and future prospects

Phytoremediation has emerged as a green, passive, solar energy driven and cost effective approach for environmental cleanup when compared to physico-chemical and even other biological methods. Textile dyes and effluents are condemned as one of the worst polluters of our precious water bodies and soils. They are well known mutagenic, carcinogenic, allergic and cytotoxic agents posing threats to all life forms. Plant based treatment of textile dyes is relatively new and hitherto has remained an unexplored area of research. Use of macrophytes like Phragmites australis and Rheum rhabarbarum have shown efficient removal of Acid Orange 7 and sulfonated anthraquinones, respectively. Common garden and ornamental plants namely Aster amellus, Portulaca grandiflora, Zinnia angustifolia, Petunia grandiflora, Glandularia pulchella, many ferns and aquatic plants have also been advocated for their dye degradation potential. Plant tissue cultures like suspension cells of Blumea malcolmii and Nopalea cochenillifera, hairy roots of Brassica juncea and Tagetes patula and whole plants of several other species have confirmed their role in dye degradation. Plants' oxidoreductases such as lignin peroxidase, laccase, tyrosinase, azo reductase, veratryl alcohol oxidase, riboflavin reductase and dichlorophenolindophenol reductase are known as key biodegrading enzymes which break the complex structures of dyes. Schematic metabolic pathways of degradation of different dyes and their environmental fates have also been proposed. Degradation products of dyes and their fates of metabolism have been reported to be validated by UV-vis spectrophotometry, high performance liquid chromatography, high performance thin layer chromatography, Fourier Transform Infrared Spectroscopy, gas chromatograph-mass spectroscopy and several other analytical tools. Constructed wetlands and various pilots scale reactors were developed independently using the plants of P. australis, Portulaca grandiflora, G. pulchella, Typha domingensis, Pogonatherum crinitum and Alternanthera philoxeroides. The developed phytoreactors gave noteworthy treatments, and significant reductions in biological oxygen demand, chemical oxygen demand, American Dye Manufacturers Institute color removal value, total organic carbon, total dissolved solids, total suspended solids, turbidity and conductivity of the dye effluents after phytoremediation. Metabolites of dyes and effluents have been assayed for phytotoxicity, cytotoxicity, genotoxicity and animal toxicity and were proved to be non/less toxic than untreated compounds. Effective strategies to handle fluctuating dye load and hydraulics for in situ treatment needs scientific attention. Future studies on development of transgenic plants for efficacious phytodegradation of textile dyes should be focused.

Sunlight mediated diesel degradation under saline conditions using ionic silver coated sand via nanoreduction: use of impregnated form of thiourea modified chitosan membranes for ex situ application

The present research investigates the use of ionic silver coated sand dust (ISSD) for the sunlight mediated degradation of diesel under saline conditions. Sand dust was used as a template for reduction of silver ions by effective removal of chloride ions. Diesel degradation was estimated in terms of degradation (%), chloride removal, volume reduction and nanoparticle synthesis, respectively. The process was optimized using a 7-level Box-Behnken design. Among several factors, time (B), Tween 80 (C), ISSD dosage (D) and silver(I) concentration (F) were found to be most significant. Maximum diesel degradation 99.8% was obtained in a period of 14 h which was analyzed by gas chromatography. XPS analysis confirmed silver reduction as the underlying phenomena. TEM analysis and albeit first approximation method confirmed that enhanced degradation occurred due to physical contact between diesel components and ISSD. First order kinetic model exhibited the best fit. Light microscopy results showed the various stages in diesel degradation by a reduction in bubble size. Ex situ application was carried out using ISSD impregnated thiourea modified chitosan/PVA membranes by surface floatation technique for the remediation of diesel contaminated sea water. Complete diesel degradation was noted after 48 h of sunlight exposure.

Biodegradation of Green HE4B: Co-substrate effect, biotransformation enzymes and metabolite toxicity analysis

A high exhaust reactive dye, Green HE4B (GHE4B) was 98% degraded in nutrient medium by Pseudomonas desmolyticum NCIM 2112 (pd2112) within 72 h at static condition. Decolorization time in synthetic 10 g/l molasses. Addition of 5 g/l peptone to NaCl medium had reduced decolorization time from 108 to 72 h. Beef extract do not contribute more to the inducing effect of peptone, however it is a good co-substrate in sucrose or urea containing NaCl medium. Intracellular lignin peroxidase (Lip), laccase and tyrosinase activities were induced by 150, 355 and 212%, respectively till maximum dye removal took place. Aminopyrine N-demethylase (AND) and dichlorophenol indophenol reductase (DCIP-reductase) activities in pd2112 were induced by 130 and 20%, respectively at 72 h of incubation during GHE4B decolorization. By high performance liquid chromatography (HPLC) analysis, 4-hydroxybenzene sulfonic acid and 4-amino, 6-hydroxynaphthalene 2-sulfonic acids were identified as metabolites formed during 24-72 h incubation. Fourier transform infrared spectroscopy (FTIR) analysis supports the formation of these aromatic amines. pd2112, aerobically degraded GHE4B metabolites (formed at static condition) showing stationary phase of 6 days. There was no germination inhibition of Sorghum bicolor and Triticum aestivum by GHE4B metabolites at 3,000 ppm concentration however untreated dye showed germination inhibition at the same concentration. GHE4B metabolites did not show any microbial toxicity at 10,000 ppm concentration.