Biodegradation Capacity Research Articles

Pipeline-Related Residential Benzene Exposure and Groundwater Natural Attenuation Capacity in the Eastern Niger Delta, Nigeria

This study was conducted to investigate the presence of benzene in the ground and drinking water in the eastern Niger Delta, where multiple oil and gas production facilities are present. Samples from drinking water wells were collected for measurements of benzene, toluene, ethylbenzene, and xylenes (BTEX). Additionally, the dissolved organic carbon (DOC) concentration was determined for the first time to establish the groundwater’s total hydrocarbon and non-hydrocarbon load. The groundwater BTEX and benzene levels were up to 3904 µg/L and 3500 µg/L, respectively. DOC concentrations were up to 49 mg/L. The highest benzene concentrations were detected in wells near an underground petroleum pipeline. However, the concentrations decreased with distance from the pipeline to levels less than 0.1 µg/L. Despite benzene contamination, the aquifer has shown promising aerobic attenuation potential, having up to a 7.5 (95%) mg/L DO level and 2.11 mg/L BTEX biodegradation capacity for DO. However, the high groundwater temperature of up to 32.5 °C may weaken attenuation. The benzene and BTEX point attenuation rates ranged from 0.128 to 0.693 day−1 and 0.086 to 0.556 day−1, respectively. Hence, by natural attenuation alone, up to 66.5 and 85 years would be required to reach Nigeria’s groundwater benzene and BTEX remediation goals, respectively.

Microbial Consortia in the Remediation of Single-Use Waste: The Case of Face Masks

This study presents the results of evaluating hydrocarbonoclastic consortia in the biodegradation of microplastics derived from single-use, triple-layered polypropylene face masks. The choice of this carbon source was driven by the need to address the increase in single-use waste generated during the recent SARS-CoV-2 pandemic, as the use of face masks was a mandatory protective measure. Two bubble column bioreactors were used, each containing hydrocarbonoclastic consortia sourced from the Port of Veracruz and the Gulf of Mexico. The biodegradation activity of these consortia was assessed by observing the physical appearance of microplastic samples under a stereoscope and a microscope, as well as by calculating the weight loss of polypropylene after 15 days. The results revealed that the consortium from the Gulf of Mexico, with a maturity of 1 year, showed a higher capacity for polypropylene biodegradation, achieving a 19.98% degradation rate. This consortium also demonstrated more stable kinetics during the experimentation period. In contrast, the younger consortium from the Port of Veracruz exhibited a lower biodegradation rate of 3.77% and variable growth kinetics. Hydrocarbonoclastic bacteria identified within the consortia included Pseudomonas aeruginosa, Enterococcus faecalis, and Vibrio parahaemolyticus, among others. The hydrocarbonoclastic consortia have the potential to biodegrade from various forms of plastic waste, including single-use face masks.

Performance of a novel Built-in Static Magnetic Field – Biological Aerated Filter (BSMF–BAF) for treating high-salt textile dyeing wastewater

High-salt textile dyeing wastewater is difficult to treat. Magnetic fields can enhance the biodegradation capacity and extreme environmental adaptabilities of microorganisms. Thus, magnetically enhanced bioreactors are expected to improve the treatment efficiency and stability of high-salt textile dyeing wastewater. Accordingly, a novel Built-in Static Magnetic Field – Biological Aerated Filter (BSMF–BAF) was constructed and investigated for treating actual high-salt textile dyeing wastewater in this study. Two other BAFs packed with traditional and magnetic ceramsite carriers, respectively, were simultaneously operated for comparison. The removal of color, chemical oxygen demand (COD), suspended solid (SS) and acute toxicity were monitored. The activities of key enzymes and microbial community structure were analyzed to reveal possible mechanisms for improving the treatment efficiency of traditional BAF using the BSMF. The results showed that the BSMF–BAF possessed the highest removal efficiencies of color, COD, SS and acute toxicity among the three BAFs. The BSMF induced significant increases in the activities of azoreductase and lignin peroxidase, which were responsible for the degradation of azo compounds in the wastewater and the detoxification of toxic intermediates, respectively. Additionally, the BSMF induced the relative enrichment of potentially effective bacteria and fungi, and it maintained a relatively high abundance of fungi in the microbial community, resulting in a high treatment efficiency.

Efficacy of Indigenous Bacteria in the Biodegradation of Hydrocarbons Isolated from Agricultural Soils in Huamachuco, Peru.

Pollution from crude oil and its derivatives poses a serious threat to human health and ecosystems, with accidental spills causing substantial damage. Biodegradation, using microorganisms to break down these contaminants, presents a promising and cost-effective solution. Exploring and utilizing new bacterial strains from underexplored habitats could improve remediation efforts at contaminated sites. This study aimed to evaluate the hydrocarbon biodegradation capacity of bacteria isolated from agricultural soils in Huamachuco, Peru. Soil samples from Oca crops were collected and bacteria were isolated. Biodegradation assays were conducted using diesel as the sole carbon source in the Bushnell Haas Mineral medium. Molecular characterization of the 16S rRNA gene identified four strains. Diesel biodegradation assays at 1% concentration were performed under agitation conditions at 150 rpm and 30 °C, and monitored on day 10 by measuring cellular biomass (OD600), with hydrocarbons analyzed by gas chromatography. The results showed Pseudomonas protegens (PROM2) achieved the highest efficiency in removing total hydrocarbons (91.5 ± 0.7%). Additionally, Pseudomonas citri PROM3 and Acinetobacter guillouiae ClyRoM5 also demonstrated high capacity in removing several individual hydrocarbons. Indigenous bacteria from uncontaminated agricultural soils present a high potential for hydrocarbon bioremediation, offering an ecological and effective solution for soil decontamination.

Methyl Red degradation by a subseafloor fungus Schizophyllum commune 15R-5-F01: efficiency, pathway, and product toxicity.

Synthetic dyes pose a significant environmental threat due to their complex structures and resistance to microbial degradation. S. commune 15R-5-F01 exhibited over 96% degradation efficiency of Methyl Red in a medium with 100 mg L-1 Methyl Red within 3 h. The fungus demonstrated adaptability to various environmental conditions, including different pH levels, temperatures, oxygen concentrations, salinity, and heavy metals. S. commune 15R-5-F01 is capable of achieving repeated cycles of Methyl Red reduction with sustained degradation duration minimum of 6 cycles. It showed a maximum Methyl Red biodegradation capacity of at least 558 mg g-1 dry mycelia and a bioadsorption capacity of 57 mg g-1. Gas chromatography-mass spectrometry analysis confirmed the azo reduction of Methyl Red into N,N-dimethyl-p-phenylenediamine and 2-aminobenzoic acid. Enzymatic activity assays indicated the involvement of lignin peroxidases, laccases, and manganese peroxidase in the biodegradation process. Phytotoxicity tests on Triticum eastivum, Oryza sativa, and Vigna umbellata seeds revealed reduced toxicity of the degradation products compared to Methyl Red. This study identifies S. commune 15R-5-F01 as a viable candidate for the sustainable degradation of synthetic dyes in industrial wastewater.

Biodecolorization and Biodegradation of Sulfur Black by the Strain Aspergillus sp. DS-28

The textile industry significantly contributes to environmental pollution through its use of synthetic dyes, especially sulfur black, known for its toxicity and resistance to degradation. This research focuses on a fungal strain, Aspergillus sp. strain DS-28, isolated from activated sludge, which exhibits an exceptional ability to biodegrade sulfur black dye. This study systematically assessed the biodegradation capacity of this strain through a series of experiments conducted over a 7-day period. Analytical techniques including high-performance liquid chromatography time-of-flight mass spectrometry (HPLC-TOF/MS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) were employed to monitor the degradation process. SEM showed a significant reduction in particle size, with surfaces becoming smoother and flatter post treatment. XRD indicated a decrease in the intensity of several chemical bonds, and FTIR analysis demonstrated the enhanced vibrational absorption peaks of benzene ring bonds, with the disappearance of -C-S- and -C-S-S-C- groups. The results demonstrate that Aspergillus sp. DS-28 degrades sulfur black by initiating the oxidative breakdown of its complex structures into simpler forms. This study not only elucidates the biodegradation pathway facilitated by Aspergillus sp. DS-28, but also highlights its potential application in developing eco-friendly waste management strategies for treating dye-contaminated wastewater.

Biodegradable chitosan hydrogel film incorporated with polyvinyl alcohol, chitooligosaccharides, and gallic acid for potential application in food packaging

The food and beverage industry worldwide is trying to switch to using environment-friendly and bio-degradable materials in food packaging to avoid environmental concerns of using petroleum-derived plastic (synthetic polymers) materials. In this study, chitosan (CH) hydrogel films were fabricated by using its derivative chitooligosaccharides (COS) as an additive, polyvinyl alcohol as a plasticiser, and bioactive gallic acid as a cross-linker. The physical, mechanical, structural, barrier (e.g., moisture, water vapour permeability (WVP), and UV-barrier property), thermal properties, and biodegradation patterns of fabricated films were investigated. The use of bio–composite in CH films exhibited a synergistic effect. A film with a homogenous/smooth surface and excellent mechanical and thermal properties was obtained. Additionally, incorporating COS and gallic acid reduced the moisture content, WVP, and transparency. Moreover, the films exhibited good colour, strong UV-barrier properties, and good biodegradable capacity in soil. The results suggest that eco-friendly CH hydrogel films have promising potential to be used in food packaging.

Microplastics Biofragmentation and Degradation Kinetics in the Plastivore Insect Tenebrio molitor.

The insect Tenebrio molitor possesses an exceptional capacity for ultrafast plastic biodegradation within 1 day of gut retention, but the kinetics remains unknown. Herein, we investigated the biofragmentation and degradation kinetics of different microplastics (MPs), i.e., polyethylene (PE), poly(vinyl chloride) (PVC), and poly(lactic acid) (PLA), in T. molitor larvae. The intestinal reactions contributing to the in vivo MPs biodegradation were concurrently examined by utilizing aggregated-induced emission (AIE) probes. Our findings revealed that the intestinal biofragmentation rates essentially followed the order of PLA > PE > PVC. Notably, all MPs displayed retention effects in the intestine, with PVC requiring the longest duration for complete removal/digestion. The dynamic rate constant of degradable MPs (0.2108 h-1 for PLA) was significantly higher than that of persistent MPs (0.0675 and 0.0501 h-1 for PE and PVC, respectively) during the digestive gut retention. Surprisingly,T. molitor larvae instinctively modulated their internal digestive environment in response to in vivo biodegradation of various MP polymers. Esterase activity and intestinal acidification both significantly increased following MPs ingestion. The highest esterase and acidification levels were observed in the PLA-fed and PVC-fed larvae, respectively. High digestive esterase activity and relatively low acidification levels inT. molitor larvae may, to some extent, contribute to more efficient MPs removal within the plastic-degrading insect. This work provided important understanding of MPs biofragmentation and intestinal responses to in vivo MPs biodegradation in plastic-degrading insects.

Phenol Biodegradation by Three Bacterial Strains Stimulated by Constant Electric Field

Objective: The aim of the present study is to compare phenol biodegradation activity of bacteria from the strains Xanthobacter autotrophicus GJ 10, Pseudomonas denitrificans and Pseudomonas putida enhanced by constant electric field in a potentiostatic mode by free cultures and immobilized cells on granulated activated carbon. Theoretical Framework: The work is based on the concept of biodegradation in constant electric field due to the enhanced removal of intermediate inhibitors produced from phenol. These intermediate may affect slightly microbial growth but the biodegradation capacity is enhanced. Method: The methodology adopted for this research comprises bioelectrochemical oxidative microbial biodegradation of phenol at constant anode potential. Results and Discussion: The obtained results revealed the positive effect of the electric field on the phenol biodegradation rate for all of the considered strains. There is certain anode potential at which the biodegradation rate is strongly affected for each strain. Research Implications: The research have both practical and theoretical implications. The practical importance consists in the enhanced biodegradation of severe pollutant as phenol is. The theoretical importance is within the specific impact of constant electric field on the enzyme activities in the studied strains. Originality/Value: This study contributes to the literature by the innovative approach and the practical aspects. The relevance and value of this research are demosntated by enhancement of phenol biodegradation in wastewater and water ponds.

Advances in plastic mycoremediation: Focus on the isoenzymes of the lignin degradation complex

This study investigates P. ostreatus and A. bisporus biodegradation capacity of low density polyethylene (LDPE) oxidised to simulate environmental weathering. Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) were used to analyse the degradation of LDPE treated with fungal cultures. Molecular implications of LDPE degradation by P. ostreatus and A. bisporus were evaluated by Reverse transcription followed by quantitative PCR (qRT-PCR) of lac, mnp and lip genes expression. After 90 days of incubation, FT-IR analysis showed, for both fungal treatments, an increasing in the intensity of peaks related to the asymmetric C-C-O stretching (1160 to 1000 cm−1) and the -OH stretching (3700 to 3200 cm−1) due to the formation of alcohols and carboxylic acid, indicating depolymerisation of LDPE. This was confirmed by the SEM analysis, where a widespread alteration of the surface morphology was observed for treated LDPE fragments. Results revealed that the exposure of P. ostreatus to oxidised LDPE treatment led to a significant increase in the expression of the lac6, lac7, lac9, lac10 and mnp2 genes, while A. bisporus showed an over-expression in lac2 and lac12 genes. The obtained results offer new perspectives for a biotechnological use of P. ostreatus and A. bisporus for plastic bioremediation.

Exploring long-term retention and reactivation of micropollutant biodegradation capacity

The factors limiting micropollutant biodegradation in the environment and how to stimulate this process have often been investigated. However, little information is available on the capacity of microbial communities to retain micropollutant biodegradation capacity in the absence of micropollutants or to reactivate micropollutant biodegradation in systems with fluctuating micropollutant concentrations. This study investigated how a period of 2 months without the addition of micropollutants and other organic carbon affected micropollutant biodegradation by a micropollutant-degrading microbial community. Stimulation of micropollutant biodegradation was performed by adding different types of dissolved organic carbon (DOC)—extracted from natural sources and acetate—increasing 10 × the micropollutant concentration, and inoculating with activated sludge. The results show that the capacity to biodegrade 3 micropollutants was permanently lost. However, the biodegradation activity of 2,4-D, antipyrine, chloridazon, and its metabolites restarted when these micropollutants were re-added to the community. Threshold concentrations similar to those obtained before the period of no substrate addition were achieved, but biodegradation rates were lower for some compounds. Through the addition of high acetate concentrations (108 mg-C/L), gabapentin biodegradation activity was regained, but 2,4-D biodegradation capacity was lost. An increase of bentazon concentration from 50 to 500 µg/L was necessary for biodegradation to be reactivated. These results provide initial insights into the longevity of micropollutant biodegradation capacity in the absence of the substance and strategies for reactivating micropollutant biodegrading communities.Graphical abstract

Screening and Evaluation of Biodegradation Potential of Bacterial Isolates Against Ethidium Bromide

Ethidium bromide (EtBr), an intercalating agent that is often employed in molecular biology procedures can bind to the DNA's minor groove, which can result in a variety of undesirable repercussions. EtBr is classified as one of the most lethal carcinogens, which makes its disposal extremely challenging and expensive. Reckless and irresponsible disposal of hazardous items can have severe impacts on the ecosystem and cause the environment's natural resources to wither away. Therefore, our study focuses on the isolation of bacterial isolates from different sources that have biodegradation potential against EtBr. Different bacterial isolates obtained from sewage water, tap water, and soil were grown in Luria Bertani (LB) broth and Nutrient agar (NA), followed by their screening and identification by performing various biochemical tests. All the isolates were grown in two different concentrations of EtBr (i.e., 30 g/ml and 60 g/ml) to determine their ability to degrade EtBr. For the current investigation, bacterial isolates obtained from the tap water (IS1, IS2, IS3, IS4, IS5, IS6) and sewage water (IS7, IS8, IS9, IS10, IS11, IS12, IS13) have shown degrading potential against EtBr at the concentration of 30µg/ml after 2 and 5 days, respectively, whereas, the bacterial isolates obtained from tap water (IS1, IS2, IS3, IS4, IS5, IS6) and sewage water (IS7, IS8, IS9, IS10, IS11, IS12, IS13) have shown degradation potential against EtBr at the concentration of 60µg/ml after 5 days and 8 days, respectively. All the isolates demonstrated EtBr bioaccumulation and were visible as vivid orange colonies under a UV transilluminator. None of the isolates obtained from the soil sample were able to degrade EtBr. The outcomes of the current investigation suggest that several bacterial isolates which were isolated from tap water and sewage water had remarkable biodegradation capacity against EtBr. The unique ability of bacterial isolates to biodegrade and accumulate EtBr can contribute to the improvement of the quality and safety of our environment. Further research into these isolates' potential for biodegrading various xenobiotics and dangerous substances could be very helpful in reducing the environment's rising toxicant concentrations.

Comparative Bioremediation of Tetradecane, Cyclohexanone and Cyclohexane by Filamentous Fungi from Polluted Habitats in Kazakhstan.

Studying the fates of oil components and their interactions with ecological systems is essential for developing comprehensive management strategies and enhancing restoration following oil spill incidents. The potential expansion of Kazakhstan's role in the global oil market necessitates the existence of land-specific studies that contribute to the field of bioremediation. In this study, a set of experiments was designed to assess the growth and biodegradation capacities of eight fungal strains sourced from Kazakhstan soil when exposed to the hydrocarbon substrates from which they were initially isolated. The strains were identified as Aspergillus sp. SBUG-M1743, Penicillium javanicum SBUG-M1744, SBUG-M1770, Trichoderma harzianum SBUG-M1750 and Fusarium oxysporum SBUG-1746, SBUG-M1748, SBUG-M1768 and SBUG-M1769 using the internal transcribed spacer (ITS) region. Furthermore, microscopic and macroscopic evaluations agreed with the sequence-based identification. Aspergillus sp. SBUG-M1743 and P. javanicum SBUG-M1744 displayed remarkable biodegradation capabilities in the presence of tetradecane with up to a 9-fold biomass increase in the static cultures. T. harzianum SBUG-M1750 exhibited poor growth, which was a consequence of its low efficiency of tetradecane degradation. Monocarboxylic acids were the main degradation products by SBUG-M1743, SBUG-M1744, SBUG-M1750, and SBUG-M1770 indicating the monoterminal degradation pathway through β-oxidation, while the additional detection of dicarboxylic acid in SBUG-M1768 and SBUG-M1769 cultures was indicative of the fungus' ability to undertake both monoterminal and diterminal degradation pathways. F. oxysporum SBUG-M1746 and SBUG-M1748 in the presence of cyclohexanone showed a doubling of the biomass with the ability to degrade the substrate almost completely in shake cultures. F. oxysporum SBUG-M1746 was also able to degrade cyclohexane completely and excreted all possible metabolites of the degradation pathway. Understanding the degradation potential of these fungal isolates to different hydrocarbon substrates will help in developing effective bioremediation strategies tailored to local conditions.

Effective and mechanistic insights into shale gas wastewater reverse osmosis concentrate treatment using ozonation-biological activated carbon process

Reverse osmosis (RO) plays a pivotal role in shale gas wastewater resource utilization. However, managing the reverse osmosis concentrate (ROC) characterized by high salinity and increased concentrations of organic matter is challenging. In this study, we aimed to elucidate the enhancement effects and mechanisms of pre-ozonation on organic matter removal efficacy in ROC using a biological activated carbon (BAC) system. Our findings revealed that during the stable operation phase, the ozonation (O3 and O3/granular activated carbon)-BAC system removes 43.6–72.2 % of dissolved organic carbon, achieving a 4–7 fold increase in efficiency compared with that in the BAC system alone. Through dynamic analysis of influent and effluent water quality, biofilm performance, and microbial community structure, succession, and function prediction, we elucidated the following primary enhancement mechanisms: 1) pre-ozonation significantly enhances the biodegradability of ROC by 4.5–6 times and diminishes the organic load on the BAC system; 2) pre-ozonation facilitates the selective enrichment of microbes capable of degrading organic compounds in the BAC system, thereby enhancing the biodegradation capacity and stability of the microbial community; and 3) pre-ozonation accelerates the regeneration rate of the granular activated carbon adsorption sites. Collectively, our findings provide valuable insights into treating ROC through pre-oxidation combined with biotreatment.

Improvement in Salt Tolerance Ability of Pseudomonas putida KT2440.

Pseudomonas putida KT2440 is a popular platform for bioremediation due to its robust tolerance to environmental stress and strong biodegradation capacity. Limited research on the salt tolerance of P. putida KT2440 has hindered its application. In this study, the strain KT2440 was tested to tolerate a maximum of 4% w/v NaCl cultured with minimal salts medium. Transcriptomic data in a high-salinity environment showed significant expression changes in genes in membrane components, redox processes, chemotaxis, and cellular catabolic processes. betB-encoding betaine-aldehyde dehydrogenase was identified from the transcriptome data to overexpress and enhance growth profile of the strain KT2440 in minimal salts medium containing 4% w/v NaCl. Meanwhile, screening for exogenous salt-tolerant genes revealed that the Na+/H+ antiporter EcnhaA from Escherichia coli significantly increased the growth of the strain KT2440 in 4% w/v NaCl. Then, co-expression of EcnhaA and betB (KT2440-EcnhaA-betB) increased the maximum salt tolerance of strain KT2440 to 5% w/v NaCl. Further addition of betaine and proline improved the salt tolerance of the engineered strain to 6% w/v NaCl. Finally, the engineered strain KT2440-EcnhaA-betB was able to degrade 56.70% of benzoic acid and 95.64% of protocatechuic acid in minimal salt medium containing 4% w/v NaCl in 48 h, while no biodegradation was observed in the normal strain KT2440 in the same conditions. However, the strain KT2440-EcnhaA-betB failed to degrade catechol in minimal salt medium containing 3% w/v NaCl. This study illustrated the improvement in the salt tolerance performance of Pseudomonas putida KT2440 and the feasibility of engineered strain KT2440 as a potential salt-tolerant bioremediation platform.

A promotion strategy of enhancing the mercury removal in Shewanella oneidensis MR-1 based on the mercury absorption and electronic consumption via mer operon

Shewanella oneidensis (S. oneidensis) bacteria have bioremediation capabilities for various heavy metals, however, their repertoire of mercury-removal proteins is limited, restricting their effectiveness in mercury remediation. In this study, the integration of an exogenous mer operon into S. oneidensis expanded the range of mercury-removal proteins, significantly boosting both mercury tolerance and removal efficiency. The engineering bacteria (MR-mer) exhibited growth in a 180 mg/L Hg2+ solution, showing a 40% increase in tolerance over S. oneidensis. In a liquid medium with 50 mg/L Hg2+, the MR-mer strain achieved 73% mercury removal efficiency, outperforming the original strain by 50%, and facilitated Hg0 formation on the cell membrane. Extensive analysis of transmembrane structures and Fourier analysis revealed that mer operon proteins might target the cell membrane, modifying its functional group contents to enhance mercury adsorption. Additionally, the absence of the key protein OmcA in the electron transport chain led to a 30% reduction in Hg2+ removal capacity. This suggests that S. oneidensis transfers electrons to the cell surface through this chain, providing electrons for Hg2+ reduction. In conclusion, the mer operon, targeting the cell membrane in MR-mer strain, synergizes with the electron transport chain to markedly elevate Hg2+ removal capability. This approach not only augments Shewanella's mercury biodegradation capacity, but also offers novel perspectives for microbial heavy metal pollutant removal.

Arabinoxylan-based psyllium seed hydrocolloid: Single-step aqueous extraction and use in tissue engineering

Biomacromolecules derived from natural sources offer superior biocompatibility, biodegradability, and water-holding capacity, which make them promising scaffolds for tissue engineering. Psyllium seed has gained attention in biomedical applications recently due to its gel-forming ability, which is provided by its polysaccharide-rich content consisting mostly of arabinoxylan. This study focuses on the extraction and gelation of Psyllium seed hydrocolloid (PSH) in a single-step water-based protocol, and scaffold fabrication using freeze-drying method. After characterization of the scaffold, including morphological, mechanical, swelling, and protein adsorption analyses, 3D cell culture studies were done using NIH-3 T3 fibroblast cells on PSH scaffold, and cell viability was assessed using Live/Dead and Alamar Blue assays. Starting from day 1, high cell viability was obtained, and it reached 90 % at the end of 15-day culture period. Cellular morphology on PSH scaffold was monitored via SEM analysis; cellular aggregates then spheroid formation were observed throughout the study. Collagen Type-I and F-actin expressions were followed by immunostaining revealing a 9- and 10-fold increase during long-term culture. Overall, a single-step and non-toxic protocol was developed for extraction and gelation of PSH. Obtained results unveiled that PSH scaffold provided a favorable 3D microenvironment for cells, holding promise for further tissue engineering applications.

Gliphosate and aminomethylphosphonic acid in the environment and their microbial transformation

Analysis of domestic and international literature indicates that the global use of glyphosate (GP), due to its effectiveness, low price and creation of herbicide-resistant agricultural crop varieties, resulted in nearly universal presence of the rest quantities of the herbicide and its main metabolite, aminomethylphosphonic acid (АМPA) in the environment: air, soil, water and crop products. Scientific information on glyphosate influence on the environment and living organisms is presented in this paper. The necessity is substantiated for periodic remediation for reducing the negative consequences of the repeated application of herbicide and detoxification of its residual quantities with the use of destructor-bacteria, capable of decomposing glyphosate and AMPA to ecologically safe compounds. The ways for glyphosate microbial transformation are reviewed. Ecologically safe detoxification assumes the use of bacterial destructors, which are destroying the phosphonic bond in glyphosate molecule. Although the bacteria of different genera are showing capacity for GP biodegradation, commercial products for the safe detoxification of glyphosate have not yet been developed due to the high level of strain specificity associated with the different ways of GF catabolism. The most perspective is the search for GP and AMPA destructors among rhizosphere bacteria, intended for application as inoculants. Complexity of the problem of GP and AMPA detoxification as well as the high level of strain specificity of bacterial destructors significantly restrain development of commercial preparations for GP and AMPA detoxification.

Isolation and Characterization of Indigenous Bacteria with Purifying Potential in Solid Palm Oil Extraction Sludge Generated by SOCAPALM-Mbambou

The oil palm industry contributes significantly to the economic development of producing countries such as Cameroon. Unfortunately, the exploitation of palm oil constitutes a source of environmental pollution due to the production of enormous quantities of waste during its extraction process, including solid sludge generating greenhouse gases which contribute to global warming climatic. All this leads to the search for alternatives which consists of isolating and characterizing indigenous bacteria with biodegradation capacities in sludge from palm oil extraction. The pH and bacterial counts were determined by the potentiometric method and the decimal dilution technique, respectively. The isolated bacteria were identified by their cultural, cellular and biochemical characteristics. In addition, the identification of Gram- bacteria was further explored by the API 20 E gallery. The palm oil biodegradability test was carried out on M2 medium supplemented with 2% palm oil. The solid sludge biodegradability test was carried out on liquid MSM medium supplemented with 4% sludge stock solution. The results showed that the sludge sample had a slightly alkaline pH of 7.3. A bacterial load of around 10<sup>9</sup> CFU/g of soil was counted. Thirty-one bacterial strains were isolated and purified, including 12 <i>Bacillus sp</i>, 10 <i>Pseudomonas sp</i>, 8 <i>Proteus mirabilis</i> and 1 <i>Klebsiella pneumoniae</i>. All isolates tested for their ability to degrade palm oil or solid sludge grew in culture media with palm oil or solid sludge as the sole source of carbon and energy but with a difference in load. Thus, isolates BI2, BI5, BI31, BI10 and BI 9 showed the highest degradation capacities. These isolates could be used to constitute consortia of microorganisms that can be used in the treatment of waste generated by palm oil extraction.

Ecological indicators and biological resources for hydrocarbon rhizoremediation in a protected area.

Spillage from oil refineries, pipelines, and service stations consistently leads to soil, food and groundwater contamination. Bacterial-assisted phytoremediation is a non-invasive and sustainable solution to eliminate or decrease the concentration of xenobiotic contaminants in the environment. In the present study, a protected area interested by a fuel discharge was considered to assess a bioremediation intervention. From the spill point, a plume of contamination flowed South-West into the aquifer, eventually reaching a wetland area. Soils, groundwaters and plants belonging to the species Scirpus sylvaticus (L.) were sampled. In the majority of the soil samples, concentrations of total petroleum hydrocarbons, both C ≤ 12 and C > 12, exceeded legal limits set forth in Directive 2000/60/EC. The analysis of diatom populations, used as ecological indicators, evidenced morphology alterations and the presence of Ulnaria ulna and Ulnaria biceps species, previously detected in hydrocarbon-polluted waters. Tests for phytotoxicity and phytodegradation, carried out in soil mesocosms, planted with Zea mays and Helianthus annuus, demonstrated that both species significantly contributed to the removal of total petroleum hydrocarbons. Removal of C ≤ 12 and C > 12 petroleum hydrocarbons was in the range of 80%-82% for Z. mays and 71%-72% for H. annuus. Microbial communities inhabiting high organic carbon and vegetated soils were more active in hydrocarbon degradation than those inhabiting subsoils, as evidenced by soil slurry experiments. The abundance of functional genes encoding toluene-benzene monooxygenase (tbmD) and alkane hydroxylase (alkB), quantified in environmental samples, confirmed that the plant rhizosphere recruited a microbial community with higher biodegradation capacity. Bacterial strains isolated from the sampling site were able to grow on model hydrocarbons (hexane, hexadecane and o-, m-, p-xylene) as sole carbon and energy sources, indicating that a natural bio-attenuation process was on-going at the site. The bacterial strains isolated from rhizosphere soil, rhizoplane and endosphere showed plant growth promoting traits according to in vitro and in vivo tests on Z. mays and Oryza sativa, allowing to forecast a possible application of bacterial assisted rhizoremediation to recover the protected area.