Phenolic removal in a model olive oil mill wastewater using Pleurotus ostreatus in bioreactor cultures and biological evaluation of the process

A New Route of Valorization of Petrochemical Wastewater: Recovery of 1,3,5-Tris (4-tert-butyl-3-hydroxy-2,6-dimethyl benzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione (Cyanox 1790) and Its Subsequent Application in a PP Matrix to Improve Its Thermal Stability

The various chemicals in industrial wastewater can be beneficial for improving its circularity. If extraction methods are used to capture valuable components from the wastewater and then recirculate them throughout the process, the potential of the wastewater can be fully exploited. In this study, wastewater produced after the polypropylene deodorization process was evaluated. These waters remove the remains of the additives used to create the resin. With this recovery, contamination of the water bodies is avoided, and the polymer production process becomes more circular. The phenolic component was recovered by solid-phase extraction and HPLC, with a recovery rate of over 95%. FTIR and DSC were used to evaluate the purity of the extracted compound. After the phenolic compound was applied to the resin and its thermal stability was analyzed via TGA, the compound's efficacy was finally determined. The results showed that the recovered additive improves the thermal qualities of the material.

Treatment technologies for olive mill wastewater with impacts on plants

Olive mill wastewater (OMW), produced during olive oil production, contains high levels of salt contents, organic matter, suspended particles, and toxic chemicals (particularly phenols), which all result in increased biological and chemical oxygen demand. Olive Oil Mills' Wastes (OMW), which have dark brown color with unpleasant smell, consist mainly of water, high organic (mainly phenols and polyphenols) and low inorganic compounds (e.g. potassium and phosphorus), as well as grease. OMW components can negatively affect soil's physical, chemical, and biological properties, rendering it phytotoxic. However, OMW can positively affect plants' development when it's applied to the soil after pretreatment and treatment processes due to its high mineral contents and organic matter. There are various approaches for removing impurities and the treatment of OMW including chemical, biological, thermal, physiochemical, and biophysical processes. Physical techniques involve filtration, dilution, and centrifugation. Thermal methods include combustion and pyrolysis; biological techniques use anaerobic and aerobic techniques, whereas adsorption and electrocoagulation act as physiochemical methods, and coagulation and flocculation as biophysical methods. In contrast, combined biological treatment methods use co-digestion and composting. A comparison of the effects of both treated and untreated OMW samples on plant development and soil parameters can help us to understand the potential role of OMW in increasing soil fertility. This review discusses the impacts of untreated OMW and treated OMW in terms of soil characteristics, seed germination, and plant growth. This review summarizes all alternative approaches and technologies for pretreatment, treatment, and recovery of valuable byproducts and reuse of OMW across the world.

Studies on the activated sludge process crucial parameters controlling olive mill wastewater treatment

Olive mill wastewater (OMW) represents a severe environmental problem for Mediterranean producer countries. The release of OMW, in urban areas, in public sewerage system constitute a serious problem for wastewater treatment plant (WWTP) based on biological processes. This study delivers a critical and a comprehensive analysis on activated sludge biomass and process crucial parameters involved in the treatment of OMW. Principal component analysis (PCA) has been applied to master the relationship between activated sludge physiological state and process performances stability. After the acclimation step with easily biodegradable synthetic substrate (SS), increased OMW F/M mass ratio has been applied to the bioreactor (60 L) of experimental pilot-scale AS system in respect to its nominal capacity. PCA highlight two main periods, a first stressful period presented by G₁[T₀-T_10%], G₂[T_20%-T_30%] and G₃[T_40%-T_50%] AS microbial communities were very sensitive to substrate changes. This was manifested by low metabolic activity (OUR, SOUR and SOUR_inh), important drop in AS microbial communities content, an increase in soluble microbial products (SMP), a fluctuate performances in COD and total phenols abatements as well as in flocks settleability (SVI). Afterwards, a reestablishment second period presented by G₄[T_60%-T_100%] of key process parameters and AS biomass efficiency indices is reached. This period characterized by the substantial content, resistance and adaption of AS microbial communities to OMW as F/M. Succeeding optimal AS biomass and process performances, under stressful conditions, requires a precise knowledge and control of decisive parameters involved in OMW treatment and this study could be an efficient practical approach in case of OMW also for further toxic compounds.

Sustainable and Eco-Friendly Conversions of Olive Mill Wastewater-Based Media by Pleurotus pulmonarius Cultures

Pleurotus pulmonarius mushroom was cultivated on liquid cultures with olive mill wastewaters (OMWs) of initial phenolic compound concentrations of 0 (control), 1, 2 and 3 g/L and glucose at initial concentrations of 40 and 60 g/L. The ability of the fungus to grow on media containing toxic compounds enriched with glucose was assessed through biomass production, glucose consumption, polysaccharide (IPS) accumulation and total cellular lipids biosynthesis, while the total phenolic compounds (TPC) and antioxidant component monitoring were also assessed during a 43-day fermentation. An analysis of the total simple sugar composition of IPS and the total fatty acid composition of lipids was performed. The phenolic reduction and media decolorization were also monitored. Results showed that the addition of glucose in OMW-based media had a positive effect on biomass, IPS and lipid production and increased the unsaturated fatty acids and TPC concentration. The maximum recorded values were the following: biomass 32.76 g/L, IPS 4.38 g/L (14.70%, w/w in dry weight), lipids 2.85 g/L (11.69%, w/w in dry weight). The mycelial lipids were unsaturated and dominated by linoleic acid, whereas IPS were composed mainly of glucose. Significant phenolic compound reduction (87–95%) and color removal (70–85%) occurred. Results strongly suggest the potentiality of P. pulmonarius utilization in the OMW treatment.

State of knowledge on chemical, biological and nutritional properties of olive mill wastewater

The Mediterranean olive oil industries are producing annually a massive quantity of olive mill wastewater (OMWW). Unfortunately, the OMWW is released arbitrarily in the nature without any pretreatment. Thus, it exhibits a high toxicity against the whole natural ecosystem including, microorganisms, plants and animals. In order to eliminate or reduce its pollution, OMWW must be properly treated prior to its release in the nature. In this regard, different treatment methods have been developed by researchers, but some of them were costly and others were inappropriate. Thus, more efforts should be made to save the nature from this pollutant. In the light of that, the current work summaries the state of knowledge regarding the OMWW from a chemical, biological, nutraceutical point of view, and the treatment methods that were used to eliminate its risk of pollution.

Simultaneous Biological Pretreatment and Saccharification of Rice Straw by Ligninolytic Enzymes from Panus neostrigosus I9 and Commercial Cellulase

The utilization of rice straw for biofuel production is limited by its composition. The pretreatment process is required to improve the enzymatic accessibility of polysaccharides in the biomass prior to enzymatic saccharification. In this study, simultaneous biological pretreatment and saccharification (SPS) of rice straw starting from laccase production by Panus neostrigosus I9 was operated in a 2-L fermenter. It was found that fungal physiology was strongly influenced by the agitation, and that the highest laccase production was obtained at an agitation speed of 750 rpm (209.96 ± 0.34 U/L). The dilution rate of 0.05 h-1 was set in continuous fermentation which resulted in laccase activity of 678.49 ± 20.39 U/L, approximately three times higher than that in batch culture. Response surface methodology (RSM) was applied to achieve the condition for maximum percentage of delignification. The maximum percentage of delignification of 45.55% was accomplished after pretreatment of rice straw with laccase enzyme 39.40 U/g rice straw at 43.70 °C for 11.19 h. Reducing sugar of 3.85 ± 0.15 g/L was obtained from the digested rice straw in a SPS reactor, while non-pretreated rice straw gave only 1.13 ± 0.10 g/L within 12 h of incubation. The results indicated that simultaneous biological pretreatment and saccharification (SPS) of rice straw by laccase helped to improve the accessibility of cellulose by cellulolytic enzymes.

α-Farnesene production from lipid by engineered Yarrowia lipolytica

Producing high value-added products from waste lipid feedstock by microbial cell factory has great advantages to minimize the pollution as well as improve the economic value of wasted oils and fats. Yarrowia lipolytica is a non-conventional oleaginous yeast and can grow on a variety of hydrophobic substrates. In this study, we explored its ability to synthesize α-farnesene, an important sesquiterpene, using lipid feedstock. Based on the α-farnesene production strain, we constructed previously, we identified that Erg12 was the key limiting factor to further increase the α-farnesene production. The α-farnesene production was improved by 35.8% through increasing the copy number of ERG12 and FSERG20 on oleic acid substrate. Expression of heterologous VHb further improved α-farnesene production by 12.7%. Combining metabolic engineering with the optimization of fermentation conditions, the α-farnesene titer and yield reached 10.2 g/L and 0.1 g/g oleic acid, respectively, in fed-batch cultivation. The α-farnesene synthesis ability on waste cooking oil and other edible oils were also explored. Compared with using glucose as carbon source, using lipid substrates obtained higher α-farnesene yield and titer, but lower by-products accumulation, demonstrating the advantage of Y. lipolytica to synthesize high value-added products using lipid feedstock.

Impact of olive mill wastewaters on the physiological behavior of a wild-type new Ganoderma resinaceum isolate

A new wild-type Ganoderma resinaceum isolate was cultivated on glucose-enriched liquid cultures with olive mill wastewaters (OMWs) in initial phenolic compounds concentrations 0.0 (control), 0.5, 0.8, and 1.5 g/l. The effect of the fungus on the reduction of phenolics and color was assessed, whereas biomass production, glucose consumption, intra-cellular (IPS) and extra-cellular (EPS) polysaccharides biosynthesis, antioxidant activity of the biomass, and laccase synthesis were monitored. Results showed that significant phenolic reduction (94.5%) and decolorization (76.5%) occurred, 14.6 g/l of biomass was produced, glucose was almost totally consumed, EPS were produced in sufficient amounts (0.79 g/l), whereas the presence of OMWs enhanced the synthesis of IPS (maximum absolute values 4.0-5.2 g/l corresponding to 35-42% w/w). Kinetic analysis demonstrated that EPS and IPS values fluctuated with time, regardless of the available amount of glucose in the media, showing a maximum in the 17th day of culture. Laccase was highly synthesized in the middle of the fermentation, reaching the maximum value of 14 U/ml. Little growth was however observed at 1.5 g/l phenolics. Strong correlation between total phenolic content and free radical scavenging activity has been noticed in the methanolic extracts of the mycelium. Results strongly suggest the potentiality of G. resinaceum utilization in the OMW waste treatment.

Production of Pleurotus sajor-caju crude enzyme broth and its applicability for the removal of bisphenol A

Bisphenol A is an endocrine interfering compound, produced and used on a large scale worldwide. Chemical and biologic methods can be used to remove it from the environment. Biological methods are considered less costly, safer and, according to green chemistry definitions, an environmentally correct method. Considering the use of a crude enzyme broth, without any downstream process, the costs could be mostly reduced. Thus, the removal of bisphenol A by Pleurotus sajor-caju crude enzyme broth was investigated. Initially, the agro-industrial wastes were characterized and, the composition of the culture medium and the bioreactor culture conditions were defined. The enzyme produced in the highest concentration was characterized and the crude broth used in the bisphenol A removal assays. The OXI45 culture medium presented the highest laccase activity (1,850.7 U L-1, 350 rpm). Greater laccase stability was observed at 20 - 40 oC and pHs 5 - 7. Vanillin and ferulic acid (considered mediator compounds) were identified in the crude broth, probably helping on the obtention of the high value of removal effectiveness (0.052 mg U-1 h-1). The results indicate the potential use of the Pleurotus sajor-caju crude enzyme broth to obtain an enzymatic formulation for application in the environmental area.

Application of olive mill waste-based biochars in agriculture: Impact on soil properties, enzymatic activities and tomato growth

The olive oil industry is an important economic sector in Mediterranean countries. However, oil production is unfortunately accompanied by the generation of huge amounts of olive mill solid wastes (OMSW) and olive mill wastewater (OMWW). In the present study, a strategy is proposed for converting these olive mill wastes into biochar through pyrolysis, for their later use as an organic amendment in agriculture. Specifically, two biochars were prepared from the pyrolysis of OMSW at 500 °C, either alone or impregnated with OMWW (OMSW-B and I-OMSW-B). The characterization of the OMSW and I-OMSW samples and their derived biochars showed that the fixed carbon and ash contents in the feedstocks increased by 38% and 11% respectively for OMSW-B, and by 37% and 12% respectively for I-OMSW-B. Interestingly, the impregnation process significantly increased Na, P, K, Ca and Fe contents in the produced biochars. The effect of OMSW-B and I-OMSW-B amendments at different application dose (1%, 2.5% and 5% wt/wt) on the enzymatic activity of an agricultural soil was performed at laboratory scale with a pot test. The experimental results showed that phosphatase and urease activity increased with biochar application rate; amendment with I-OMSW-B at 1%, 2.5% and 5% enhanced the phosphatase activity by 63%, 142% and 285% and urease activity by 50%, 116% and 149%, respectively. On the other hand, dehydrogenase and protease activities were higher for the application rate of 2.5% biochar. Biochar amendment promoted tomatoes seedling growth after 10 weeks, which was highest in the application rates of 2.5% and 5% for both OMSW-B and I-OSMW-B. Thus, the produced biochars had great potential to be used as biofertilizers in agriculture.

Effect of polyphenols on activated sludge biomass during the treatment of highly diluted olive mill wastewaters: biomass dynamics and purifying performances

This study aims to investigate the feasibility of treating olive mill waste water (OMWW) by activated sludge pilot (AS) after its high dilution (1%) by urban waste water (UWW) and to study the effect of polyphenol compounds on the biomass during the treatment. Specific oxygen uptake rate (SOUR), mixed liquor volatile suspended solids (MLVSS), chemical oxygen demand (COD) and total polyphenols, were followed up over 100 days. In spite of the polyphenols' high concentration (up to 128 mg·L^-1), successful biomass growth of 7.12 g _MLVSS.L ^-1 and activity were achieved. Most of the bacteria (Pseudomonas sp., Klebsiella oxytoca, Citrobacter fereundii, Escherichia coli and Staphylococcus sp.) and fungi (Trichoderma sp., Rhizopus sp., Aspergillus niger, Penicillium sp., Fusarium sp., Alternaria) identified in the aerobic basin during the stabilization stage were known to be resistant to OMWW and showed effective adaptation of the biomass to polyphenols in high concentration. COD and polyphenols were highly eliminated (90%, 92% respectively). The sludge volume index in the pilot settling tank was almost constant at around 120 mL.g ^-1. This suggests the possibility of managing OMWW by simple injection at a given percentage in already functioning conventional AS treating UWW.

Lipid Production by Yeasts Growing on Commercial Xylose in Submerged Cultures with Process Water Being Partially Replaced by Olive Mill Wastewaters

Six yeast strains belonging to Rhodosporidium toruloides, Lipomyces starkeyi, Rhodotorula glutinis and Cryptococcus curvatus were shake-flask cultured on xylose (initial sugar—S0 = 70 ± 10 g/L) under nitrogen-limited conditions. C. curvatus ATCC 20509 and L. starkeyi DSM 70296 were further cultured in media where process waters were partially replaced by the phenol-containing olive mill wastewaters (OMWs). In flasks with S0 ≈ 100 g/L and OMWs added yielding to initial phenolic compounds concentration (PCC0) between 0.0 g/L (blank experiment) and 2.0 g/L, C. curvatus presented maximum total dry cell weight—TDCWmax ≈ 27 g/L, in all cases. The more the PCC0 increased, the fewer lipids were produced. In OMW-enriched media with PCC0 ≈ 1.2 g/L, TDCW = 20.9 g/L containing ≈ 40% w/w of lipids was recorded. In L. starkeyi cultures, when PCC0 ≈ 2.0 g/L, TDCW ≈ 25 g/L was synthesized, whereas lipids in TDCW = 24–28% w/w, similar to the experiments without OMWs, were recorded. Non-negligible dephenolization and species-dependent decolorization of the wastewater occurred. A batch-bioreactor trial by C. curvatus only with xylose (S0 ≈ 110 g/L) was performed and TDCW = 35.1 g/L (lipids in TDCW = 44.3% w/w) was produced. Yeast total lipids were composed of oleic and palmitic and to lesser extent linoleic and stearic acids. C. curvatus lipids were mainly composed of nonpolar fractions (i.e., triacylglycerols).

Deriving valorization of phenolic compounds from olive oil by-products for food applications through microencapsulation approaches: a comprehensive review

Nowadays, olive oil consumption is correlated to many health benefits, essentially due to the presence of antioxidants, especially phenolic compounds, which fostered its intensive production worldwide. During olive oil extraction, through continuous or discontinuous processes, many olive oil by-products are generated. These by-products constitute an environmental problem regarding its management and disposal. They are phytotoxic and biotoxic due to their high content of phenolic compounds, presenting contrastingly relevant health benefits due to their potent radical scavenging activities. In the framework of the disposal and management of olive oil by-products, treatment, and valorization approaches are found. As currently, the majority of the valorization techniques applied have a null market value, alternative strategies for the obtainment of innovative products as fortified foods are being investigated. The recovery and valorization strategies of olive oil by-products may comprise extraction and further encapsulation of bioactive compounds, as an innovative valorization blueprint of phenolic compounds present in these by-products. The majority of phenolic compounds present in olive oil by-products possess limited application on the food industry since they are promptly amended by environmental factors like temperature, pH, and light. Consequently, they must be protected previously ending in the final formulation. Prior to foods fortification with phenolic-rich extracts obtained from olive oil by-products, they should be protected through microencapsulation approaches, allowing a sustained release of phenolic compounds in the fortified foods, without losing their physicochemical properties. The combined strategies of extraction and microencapsulation will contribute to promoting the sustainability of the olive oil sector and aid the food industry to obtain reinvented added-value products.

Spent mushroom substrate for a second cultivation cycle of Pleurotus mushrooms and dephenolization of agro-industrial wastewaters

Spent mushroom substrate (SMS) of Pleurotus ostreatus was supplemented with wheat bran and soybean flour and used as substrate for a new cultivation cycle of the oyster mushrooms Pleurotus ostreatus and Pleurotus pulmonarius. The bioconversion efficiency of mushrooms produced over substrate (BE%) used and the chemical composition of sporophores were evaluated. The concentration of mycelial mass, crude exopolysaccharide content and laccase enzyme activity were also determined at the supplemented SMS before inoculation, at 50% and 100% of colonization stages in the new cultivation and in the final re-utilized SMS. The laccase enzyme was extracted to examine SMS potential for the dephenolization of olive mill and winery wastewaters. Results showed that both Pleurotus species exhibited BE over 185%, demonstrating this bioprocess could represent a promising strategy to convert SMS into nutritional food. Data also indicate the strong positive impact that SMS could have in the solid wastes’ management and agribusiness enhancement.

Mycoremediation of PCBs by Pleurotus ostreatus: Possibilities and Prospects

With the rising awareness on environmental issues and the increasing risks through industrial development, clean up remediation measures have become the need of the hour. Bioremediation has become increasingly popular owing to its environmentally friendly approaches and cost effectiveness. Polychlorinated biphenyls (PCBs) are an alarming threat to human welfare as well as the environment. They top the list of hazardous xenobiotics. The multiple effects these compounds render to the niche is not unassessed. Bioremediation does appear promising, with myco remediation having a clear edge over bacterial remediation. In the following review, the inputs of white-rot fungi in PCB remediation are examined and the lacunae in the practical application of this versatile technology highlighted. The unique abilities of Pleurotus ostreatus and its deliverables with respect to removal of PCBs are presented. The need for improvising P. ostreatus-mediated remediation is emphasized.

Effect of Salt Addition upon the Production of Metabolic Compounds by Yarrowia lipolytica Cultivated on Biodiesel-Derived Glycerol Diluted with Olive-Mill Wastewaters

One of the major environmental problems is the highly toxic agro-industrial waste called olive mill wastewater (OMW), deriving from olive oil production. On the other hand, the continuous development of the biological liquid fuel industry (biodiesel and bioethanol) makes it mandatory the process and exploitation of their main by-products, crude glycerol. This study dealt with the biotechnological conversions of biodiesel-derived crude glycerol with the use of the non-conventional yeast Yarrowia lipolytica in media that had been diluted with OMWs. OMWs, employed as simultaneous liquid medium and substrate, is a new trend recently appearing in Industrial Biotechnology, where value-added metabolites could be produced with simultaneous partial detoxification (i.e. decolorization and phenol removal) of the used residue. In the present study, diluted OMWs (containing 2.0 g/L of total phenolic compounds) blended with 70.0 g/L crude glycerol were employed as substrates. Production of value-added compounds by Y. lipolytica strain ACA-YC 5031 was studied in nitrogen-limited media favoring the production of secondary metabolites (i.e. citric acid, polyols, microbial lipids, polysaccharides). Batch-flask cultures were carried out and the impact of the addition of different NaCl concentrations (1.0%, 3.0%, 5.0% w/w) added upon the biochemical behavior of the strain was studied. Remarkable biomass production was observed in all trials, while in the “blank” experiment (no OMWs and no salt added), the metabolism was shifted toward the synthesis of polyols (Σpolyols = mannitol + arabitol + erythritol > 20 g/L and maximum total citric acid-Cit (sum of citric and isocitric acid) = 10.5 g/L). Addition of OMWs resulted in Citmax = 32.7 g/L, while Σpolyols concentration dropped to <15 g/L. Addition of salt in the OMW-based media slightly reduced the produced biomass, while Cit production drastically increased, reaching a final value of 54.0 g/L (conversion yield of Cit produced per unit of glycerol consumed = 0.82 g/g) in the trial with addition of 5.0% NaCl. Finally, significant color and phenols removal were observed, evaluating the yeast as a decontamination medium for the OMW and a great candidate for the production of value-added compounds.

Phenol removal by laccases and other phenol oxidases of Pleurotus sajor-caju PS-2001 in submerged cultivations and aqueous mixtures

In this work, phenol removal from aqueous solutions by Pleurotus sajor-caju PS-2001 phenol oxidases was assessed under different conditions. In stirred-tank reactor (STR), 77, 82, 92 and 36% of removal were attained when initial concentrations of 1.0, 2.0, 3.0 and 4.0 mmol L^-1 phenol, respectively, were used. Among the different enzymes produced by this fungus, phenol removal seems to be related to the activity of laccases that attained maximum values between 33 and 91 U mL^-1 in STR. With an internal-loop airlift reactor (ILAR), phenol concentrations of 1.0, 2.0, 3.0, 4.0 and 5.0 mmol L^-1 were evaluated, and removal of 70, 76, 82, 77 and 82%, respectively, were observed. In ILAR, however, superior maximum titres of laccases were quantified (80-285 U mL^-1). Crude enzyme broths have also been tested for phenol removal from 3.0 mmol L^-1 aqueous solutions, the best result (55% of removal) being obtained at pH 3.2 and 30 °C, without agitation, using 60 U mL^-1 laccases. According to the data presented, phenol can be efficiently removed from liquid media in submerged cultures of P. sajor-caju PS-2001 even when carried out in a simple pneumatic reactor, whereas significantly less amount of the pollutant is degraded when a crude enzyme broth is used.

Production of Added-Value Chemical Compounds through Bioconversions of Olive-Mill Wastewaters Blended with Crude Glycerol by a Yarrowia lipolytica Strain

Olive mill wastewaters (OMW) are the major effluent deriving from olive oil production and are considered as one of the most challenging agro-industrial wastes to treat. Crude glycerol is the main by-product of alcoholic beverage and oleochemical production activities including biodiesel production. The tremendous quantities of glycerol produced worldwide represent a serious environmental challenge. The aim of this study was to assess the ability of Yarrowia lipolytica strain ACA-DC 5029 to grow on nitrogen-limited submerged shake-flask cultures, in crude glycerol and OMW blends as well as in media with high initial glycerol concentration and produce biomass, cellular lipids, citric acid and polyols. The rationale of using such blends was the dilution of concentrated glycerol by OMW to (partially or fully) replace process tap water with a wastewater stream. The strain presented satisfactory growth in blends; citric acid production was not affected by OMW addition (Citmax~37.0 g/L, YCit/Glol~0.55 g/g) and microbial oil accumulation raised proportionally to OMW addition (Lmax~2.0 g/L, YL/X~20% w/w). Partial removal of color (~30%) and phenolic compounds (~10% w/w) of the blended media occurred. In media with high glycerol concentration, a shift towards erythritol production was noted (Erymax~66.0 g/L, YEry/Glol~0.39 g/g) simultaneously with high amounts of produced citric acid (Citmax~79.0 g/L, YCit/Glol~0.46 g/g). Fatty acid analysis of microbial lipids demonstrated that OMW addition in blended media and in excess carbon media with high glycerol concentration favored oleic acid production.

The influence of Tween 80 on laccase production by Pleurotus sajor-caju and the efficiency of crude enzyme broth in the removal of bisphenol-A

ABSTRACT: Bisphenol-A is currently considered an environmental pollutant, capable of interfering in the endocrine system of organisms and causing alterations in its development and reproductive system. An alternative method to the chemical treatment of this pollutant has been the use of oxidative enzymes, especially laccases produced by fungi. In order to reduce production costs, agro-industrial waste can be used in the culture medium composition. Nonionic surfactants, which are only slightly toxic to biological membranes, can be applied, as well as Tween 80, to facilitate the excretion of these enzymes into the culture medium. The objectives of this work were: a) characterize the immersion water of banana straw used in the formulation of the culture medium; b) evaluate laccase production by Pleurotus sajor-caju in culture medium with and without addition of Tween 80, through shaken flasks; c) evaluate the efficiency of the crude enzyme broth in degrading bisphenol-A. The shaken flasks were incubated at 30°C for 12 days. The immersion water had a C:N ratio of 13.8, ash percentage of 28.6%, and pH close to neutrality. The addition of Tween 80 on the culture medium (7.5%, m/v) yielded laccase activity and productivity values equal to 3,016.47 U L-1 and 502.7 U L-1 day-1, respectively. These values were 50 and 33.5 times higher than those obtained in the culture medium without addition of Tween 80 for laccase activity and productivity, respectively. The crude enzyme broth degraded 100% of bisphenol-A after 48 hours, regardless of concentration (500, 750 and 1,000 mg L-1).

Treatment of olive mill wastewater through employing sequencing batch reactor: performance and microbial diversity assessment

This work describes the performance of a sequencing batch reactor (SBR) and the involvement of a novel reconstituted bacterial consortium in olive mill wastewater (OMW) treatment. The organic loading rate applied to the SBR was serially increased in terms of initial COD from 10 to 75 g L^-1 to allow gradual acclimatization of activated sludge to high concentrations of toxic compounds in OMW. After the acclimatization period, up to 60% of the total COD content were effectively biodegraded from OMW at 75 g L^-1 COD within 30 day hydraulic retention time. The diversity and community composition of cultivable bacteria participating in the aerobic process of treating OMW were further assessed. A total of 91 bacterial strains were isolated from the reactor and analyzed by amplification of the 16S-23S rRNA internal transcribed spacer (ITS) region and by 16S rRNA gene sequencing. The most abundant phylum was Firmicutes (57.1%) followed by Proteobacteria (35.2%) and Actinobacteria (7.7%). The use of the Biolog® Phenotype Microarray system to evaluate the ability of isolated strains to utilize OMW phenolic compounds is reported in this work for the first time. Interestingly, results showed that all species tested were able to utilize phenolics as sole carbon and energy sources. The removals of COD and phenolics from undiluted OMW by the reconstituted bacterial consortium were almost similar to those obtained by the acclimatized activated sludge, which suggest that cultivable bacteria play the major role in OMW biodegradation. Phytotoxicity assays using tomato seeds showed a significant improvement of seed germination values for treated OMW. Our overall results suggest that the novel developed bacterial consortium could be considered as a good prospect for phenolics-rich wastewaters bioremediation applications.

Biostimulant Potential of Humic Acids Extracted From an Amendment Obtained via Combination of Olive Mill Wastewaters (OMW) and a Pre-treated Organic Material Derived From Municipal Solid Waste (MSW)

Olive mill wastewaters (OMW) contain significant levels of phenolic compounds with antimicrobial/phytotoxic activity and high amounts of undecomposed organic matter that may exert negative effects on soil biology. Among OMW detoxification techniques, those focusing on oxidative degradation of phenolic compounds are relevant. The composting (bio-oxidation) process in particular, exploits exothermic oxidation reactions by microorganisms to transform the organic matrix of OMW into an amendment biologically stable and feasible to use in agriculture. This process consists of an active phase during which organic compounds are rapidly decomposed, and a curing phase characterized by a slow breakdown of the remaining materials with the formation of humic substances (HS) as by-products. In this study, bio-oxidation of OMW was performed using a pre-treated organic material derived from municipal solid waste (MSW). The obtained amendment (OMWF) was stable and in accordance with the legislative parameters of mixed organic amendments. HS were then extracted from OMWF and MSW (control amendment, Amd-C), and differences in structural properties of their humic acid (HA) fraction were highlighted via spectroscopy (Fourier Transform Infrared) and Dynamic Light Scattering. To assay a potential use of HA as biostimulants for crops, 12-day old Zea Mays L. plants were supplied with HA at 0.5 mg and 1 mg C L-1 for 2 days. HA from both amendments increased plant growth, but HA from OMWF was more effective at both dosages (plus 35-37%). Also, HA from OMWF enhanced both nitrogen assimilation and glycolysis by increasing the activity of nitrate reductase (∼1.8-1.9 fold), phosphoglucose isomerase (PGI) (∼1.8-2 fold) and pyruvate kinase (PK) (∼1.5-1.8 fold), while HA from Amd-C targeted glycolysis preferentially. HA from OMWF, however, significantly stimulated plant nutrition only at lower dosage, perhaps because certain undetermined compounds from detoxified OMW and incorporated in HA altered the root membrane permeability, thus preventing the increase of nutrient uptake. Conversely, HA from Amd-C increased nutrient accumulation in maize at both dosages. In conclusion, our results indicate that the amendment obtained via OMW composting using MSW had a reduced pollution load in terms of phenolic compounds, and HA extracted from OMWF could be used as valuable biostimulants during maize cultivation.

Alternative Substrate Metabolism in Yarrowia lipolytica

Recent advances in genetic engineering capabilities have enabled the development of oleochemical producing strains of Yarrowia lipolytica. Much of the metabolic engineering effort has focused on pathway engineering of the product using glucose as the feedstock; however, alternative substrates, including various other hexose and pentose sugars, glycerol, lipids, acetate, and less-refined carbon feedstocks, have not received the same attention. In this review, we discuss recent work leading to better utilization of alternative substrates. This review aims to provide a comprehensive understanding of the current state of knowledge for alternative substrate utilization, suggest potential pathways identified through homology in the absence of prior characterization, discuss recent work that either identifies, endogenous or cryptic metabolism, and describe metabolic engineering to improve alternative substrate utilization. Finally, we describe the critical questions and challenges that remain for engineering Y. lipolytica for better alternative substrate utilization.

Biomass behaviour in a conventional activated sludge system treating olive mill wastewater

The current work aims to study the biomass behaviour in a continuous mode activated sludge system (ASS) treating olive mill wastewater (OMWW) through an increasing OMWW food to microorganism ration (F/M). To this end, the biomass growth, the specific oxygen uptake rate (SOUR), microbial characterization, sludge volume index (SVI) as well as COD and phenolic compounds removal efficiencies were examined over time. Results showed a successful growth of the biomass that reached 6.79 g_TSS l^-1 and 5.42 g_VSS l^-1. Its viability, its adaptability, and its good physiological activity were confirmed by the obtained result of SOUR with an average of 9.95 mg_O2 g_VSS^-1h^-1, as well as aerobic microbial population characterization in terms of aerobic revivable bacteria at 22°C and 37°C, Pseudomonas sp., mould and yeast and total fungi. The concentration of these strains characterized by their ability to degrade effectively COD and phenolic compounds increased significantly (p < .05) over time. This demonstrated a great promptness in response to the increasing OMWW mass ratio. For all treatment steps, removal efficiencies were high and reached 95% of COD and 93% of phenolic compounds, also the flocs settleability shown by SVI measurement was optimal.

Genotoxic effects of olive oil wastewater on sunflower

The aim of this study is to determine in detail the genotoxic effects of Olive Oil Wastewater (OOWW) on sunflower. For this reason, different concentrations of OOWW (1/1,1/10,1/100) were applied as irrigation water to sunflowers at different times (3-day, 5-day, 10-day). In the plants taken during these times, RAPD-based genomic template stability (GTS) assays and gene expression (transcriptomic) levels of different free radical scavenging enzyme genes (SOD, CAT, SOD2, GST, GPX, APX), protein repair/chaperoning genes (HSP26, HSP70, HSP83), N metabolism gene (GS) and apoptotic genes (BAX, BCL2, BCLXL, CYT-C, XIAP) were compared to the those of the control (OOWW-free) group. As a result; The GTS rates seemed to be fairly lower than the control and therefore the OOWW was likely to cause significant damage to the DNA's nucleotide and genomic structure, and the GTS value increased inversely proportional when the OOWW concentration was reduced from 1/1 to 1/10, and after a 10-day application, it seemed to be partly healing. In transcriptomic analysis; all OOWW experiments caused a free radical threat, and especially in 5-day OOWW applications, this raised significantly almost all expressions of antioxidants, protein repair, N metabolism, and apoptotic genes. So, the damages of 5-day OOWW treatments were found to be relatively more than those of 3-day treatments. Regarding 10-day transcriptomic data; a partial repair was found. Additionally, it was determined that the values of B, F, Al, Mn, Ni, Cr, As, Se, Cd, Pb and total polyphenols were high in OOWW. Our findings were also supported by plant images and various heavy metals' and OOWW polyphenols' toxicity results. Our results pointed to key findings in OOWW genotoxicology.

Degradation of olive mill wastewater by the induced extracellular ligninolytic enzymes of two wood-rot fungi

Olive mill wastewater (OMWW) is a major problem in olive oil - producing countries, due to its high organic load and concentration in phenols that are toxic for marine life, plants and soil microorganisms. In the present study, two mushroom species were tested in regard to their OMWW's oxidative capacity, Pleurotus citrinopileatus LGAM 28684 and Irpex lacteus LGAM 238. OMWW (25% v/v) degradation was investigated for several culture conditions, namely pH, agitation speed, nitrogen-based supplements and their concentration. The selected values were pH 6, agitation rate 150 rpm, 30 g L^-1 corn steep liquor as nitrogen source for P. citrinopileatus and 20 g L^-1 diammonium tartrate for I. lacteus. The two strains performed well in cultures supplemented with OMWW, generating very high titers of oxidative enzymes and achieving more than 90% color and phenols reduction within a 24 days cultivation period. In addition, the amount of glucans present in the fungal biomass was assessed. Hence, P. citrinopileatus and I. lacteus appear as potent degraders of OMWW with the ability to use the effluent as a substrate for the production of biotechnologically important enzymes and valuable fungal glucans.

Kinetic studies on the removal of phenol by MBBR from saline wastewater

BACKGROUND

Phenols are chemical compounds which are included in the high priority of pollutants by environmental protection agency (USEPA). The presence of high concentrations of phenols in wastewaters like oil refineries, petrochemical plants, olive oil, pesticide production and oil field operations contain high soluble solids (TDS) and in an olive oil plant, wastewater is acidic, high salty and phenol concentrations are in the range of 0.1- 1%.

METHODS

Kinetic parameters were calculated according to Monod, Modified Stover- Kincannon, Hamoda and Haldane models. The influence of different initial phenol concentrations on the biodegradation rate was performed. The concentrations of phenol varied from 0 to 500 mg/l.

RESULTS

The value of K_i in saline phenolic wastewater in attached growth systems was higher than suspended growth systems that represented a higher phenol inhibition in suspended growth systems. It was obvious that the best model fitting the obtained data are Hamoda model and the Modified Stover-Kincannon model, having highest R² values of 0.991 and 1, respectively. The value of K_i in saline phenolic wastewater in attached growth system was higher than suspended growth systems which represented a higher phenol inhibition in suspended growth systems.

CONCLUSIONS

Hamoda model and the Modified Stover-Kincannon model having highest R2 value of 0.991 and 1, respectively, and also predicting reasonable kinetic coefficient values.

Production of added-value metabolites by Yarrowia lipolytica growing in olive mill wastewater-based media under aseptic and non-aseptic conditions

Yarrowia lipolytica ACA-YC 5033 was grown on glucose-based media in which high amounts of olive mill wastewaters (OMWs) had been added. Besides shake-flask aseptic cultures, trials were also performed in previously pasteurized media while batch bioreactor experiments were also done. Significant decolorization (∼58%) and remarkable removal of phenolic compounds (∼51% w/w) occurred, with the latter being amongst the highest ones reported in the international literature, as far as yeasts were concerned during their growth on phenol-containing media. In nitrogen-limited flask fermentations the microorganism produced maximum citric acid quantity ≈19.0 g/L [simultaneous yield of citric acid produced per unit of glucose consumed (Y_Cit/Glc)≈0.74 g/g]. Dry cell weight (DCW) values decreased at high phenol-containing media, but, on the other hand, the addition of OMWs induced reserve lipid accumulation. Maximum citric acid concentration achieved (≈52.0 g/L; Y_Cit/Glc≈0.64 g/g) occurred in OMW-based high sugar content media (initial glucose added at ≈80.0 g/L). The bioprocess was successfully simulated by a modified logistic growth equation. A satisfactory fitting on the experimental data occurred while the optimized parameter values were found to be similar to those experimentally measured. Finally, a non-aseptic (previously pasteurized) trial was performed and its comparison with the equivalent aseptic experiment revealed no significant differences. Yarrowia lipolytica hence can be considered as a satisfactory candidate for simultaneous OMWs bioremediation and the production of added-value compounds useful for the food industry.

Soil contamination with olive mill wastes negatively affects microbial communities, invertebrates and plants

The aim of the present study was to evaluate the ecotoxicological effects of olive mill waste (OMW) on soil habitat function. To this end, soil samples from OMW evaporating ponds (S1-S5) located at Agareb (Sfax, Tunisia) and a reference soil (R) were collected. The effects of OMW on the springtails Folsomia candida (F.c.), the earthworm species Eisenia fetida (E.f.), Enchytraeus crypticus (E.c.) reproduction and on the soil living microbial communities were investigated. E.f. reproduction and tomato growth assays were performed in the reference soil amended with 0.43 to 7.60 % (w_OMW/w_ref-soil) mass ratios of dried OMW. Changes in microbial function diversity were explored using sole-carbon-source utilization profiles (BiologEcoPlates^®). E.f. absolutely avoided (100 %) the most polluted soil (S4) while the F.c. moderately avoided (37.5 ± 7.5 %) the same soil. E.c. reproduction in S4 was significantly lower than in S1, S2, S3 and S5, and was the highest in R soil. Estimated effect concentration EC₅₀ for juveniles' production by E.f., and for tomato fresh weight and chlorophyll content were 0.138, 0.6 and 1.13 %, respectively. Community level physiological profiles (CLPPs) were remarkably different in R and S4 and a higher similarity was observed between soils S1, S2, S3 and S5. Principal component analysis (PCA) revealed that differences between soil microbial functional diversity were mainly due to high polyphenol concentrations, while the salinity negatively affected E.c. reproduction in OMW contaminated soils. These results clearly reflect the high toxicity of dried OMW when added to agricultural soils, causing severe threats to terrestrial ecosystem functions and services provided by invertebrates and microbial communities.

Identification and Characterization of Small Noncoding RNAs in Genome Sequences of the Edible Fungus Pleurotus ostreatus

Noncoding RNAs (ncRNAs) have been identified in many fungi. However, no genome-scale identification of ncRNAs has been inventoried for basidiomycetes. In this research, we detected 254 small noncoding RNAs (sncRNAs) in a genome assembly of an isolate (CCEF00389) of Pleurotus ostreatus, which is a widely cultivated edible basidiomycetous fungus worldwide. The identified sncRNAs include snRNAs, snoRNAs, tRNAs, and miRNAs. SnRNA U1 was not found in CCEF00389 genome assembly and some other basidiomycetous genomes by BLASTn. This implies that if snRNA U1 of basidiomycetes exists, it has a sequence that varies significantly from other organisms. By analyzing the distribution of sncRNA loci, we found that snRNAs and most tRNAs (88.6%) were located in pseudo-UTR regions, while miRNAs are commonly found in introns. To analyze the evolutionary conservation of the sncRNAs in P. ostreatus, we aligned all 254 sncRNAs to the genome assemblies of some other Agaricomycotina fungi. The results suggest that most sncRNAs (77.56%) were highly conserved in P. ostreatus, and 20% were conserved in Agaricomycotina fungi. These findings indicate that most sncRNAs of P. ostreatus were not conserved across Agaricomycotina fungi.

Investigation of olive mill wastewater (OMW) ozonation efficiency with the use of a battery of selected ecotoxicity and human toxicity assays

The effects of olive mill wastewater (OMW) on a battery of biological assays, before and during the ozonation process, were investigated in order to assess ozone's efficiency in removing phenolic compounds from OMW and decreasing the concomitant OMW toxicity. Specifically, ozonated-OMW held for 0, 60, 120, 300, 420, 540min in a glass bubble reactor, showed a drastic reduction of OMW total phenols (almost 50%) after 300min of ozonation with a concomitant decrease of OMW toxicity. In particular, the acute toxicity test primarily performed in the fairy shrimp Thamnocephalus platyurus (Thamnotoxkit F™ screening toxicity test) showed a significant attenuation of OMW-induced toxic effects, after ozonation for a period of 120 and in a lesser extent 300min, while further treatment resulted in a significant enhancement of ozonated-OMW toxic effects. Furthermore, ozonated-OMW-treated mussel hemocytes showed a significant attenuation of the ability of OMW to cause cytotoxic (obtained by the use of NRRT assay) effects already after an ozonation period of 120 and to a lesser extent 300min. In accordance with the latter, OMW-mediated oxidative (enhanced levels of superoxide anions and lipid peroxidation by-products) and genotoxic (induction of DNA damage) effects were diminished after OMW ozonation for the aforementioned periods of time. The latter was also revealed by the use of cytokinesis block micronucleus (CBMN) assay in human lymphocytes exposed to different concentrations of both raw- and ozonated-OMW for 60, 120 and 300min. Those findings revealed for a first time the existence of a critical time point during the OMW ozonation process that could be fundamentally used for evaluating OMW ozonation as a pretreatment method of OMW.

Degradation of Bunker C Fuel Oil by White-Rot Fungi in Sawdust Cultures Suggests Potential Applications in Bioremediation

Fungal lignocellulolytic enzymes are promising agents for oxidizing pollutants. This study investigated degradation of Number 6 “Bunker C” fuel oil compounds by the white-rot fungi Irpex lacteus, Trichaptum biforme, Phlebia radiata, Trametes versicolor, and Pleurotus ostreatus (Basidiomycota, Agaricomycetes). Averaging across all studied species, 98.1%, 48.6%, and 76.4% of the initial Bunker C C10 alkane, C14 alkane, and phenanthrene, respectively were degraded after 180 days of fungal growth on pine media. This study also investigated whether Bunker C oil induces changes in gene expression in the white-rot fungus Punctularia strigosozonata, for which a complete reference genome is available. After 20 days of growth, a monokaryon P. strigosozonata strain degraded 99% of the initial C10 alkane in both pine and aspen media but did not affect the amounts of the C14 alkane or phenanthrene. Differential gene expression analysis identified 119 genes with ≥ log₂(2-fold) greater expression in one or more treatment comparisons. Six genes were significantly upregulated in media containing oil; these genes included three enzymes with potential roles in xenobiotic biotransformation. Carbohydrate metabolism genes showing differential expression significantly accumulated transcripts on aspen vs. pine substrates, perhaps reflecting white-rot adaptations to growth on hardwood substrates. The mechanisms by which P. strigosozonata may degrade complex oil compounds remain obscure, but degradation results of the 180-day cultures suggest that diverse white-rot fungi have promise for bioremediation of petroleum fuels.

Evaluation of phytotoxicity effect of olive mill wastewater treated by different technologies on seed germination of barley (Hordeum vulgare L.)

Olive-mill wastewater (OMW) is a by-product effluent of olive oil extraction process that is produced in large amount in the Mediterranean region. OMW is believed to induce phytotoxic effect on organisms including seed germination and plant growth. The objective of this study was to evaluate the impact of untreated and treated OMW with different techniques on seed germination of barley (Hordeum vulgare L.). The following treatments were investigated: (1) tap water (control); (2) OMW treated by aerobic biological technology in a Jacto Reactor (JR); (3) OMW treated by solar fenton oxidation (SFO); (4) OMW treated by microfiltration followed by nanofiltration (MF+NF); (5) OMW treated by microfiltration followed by reverse osmosis (MF+RO) process; (6) diluted OMW with tap water (25 % OMW); (7) diluted OMW with tap water (50 % OMW); (8) diluted OMW with tap water (75 % OMW); and (9) untreated OMW (100 % OMW). A germination test was conducted in an incubator at temperature of 23 (∘)C. In each petri dish, a filter paper was mounted and ten seeds of barley were placed on the filter paper. Five milliliter of water were added to each petri dish. The seed germination was determined by counting the number of germinated seeds to calculate the percentage of germination (G %). Germination rate index (GRI), seed vigor index (SVI), and phytotoxicity index (PI) were also calculated. Then, the dry weights and lengths of the shoots and the roots of the germinated seeds were measured. The results show that 100, 75, and 50 %OMW were very phytotoxic and completely prohibited seed germination. However, phytotoxicity decreased significantly following treatments of OMW with all techniques investigated and by the 25 % OMW dilution, as results of removing the phenols and other phytotoxic organic compounds from the OMW or by diluting it. This was evidenced by relative enhancement of the dry weights and lengths of shoot and root as well as the G %, GRI, SVG, and PI. It was concluded that if OMW will be used for irrigating crops, it has to be first treated or diluted with tap water at a ratio of 1:3 OMW:water at least. The most efficient treatment techniques in reducing the phytotoxicity of OMW were the MF+RO, followed by SFO and JR.

Olive mill wastewater treatment using a simple zeolite-based low-cost method

Olive mill wastewater (OMW), a liquid by-product of the olive oil industry, represents a severe environmental problem owing to its high pollution load. In this study, successive columns containing different types of natural materials were investigated for their OMW treatment efficiency. Passing OMW through three columns of gravel, fine sand, and a mixture of acidified cotton and zeolite (weight:weight ratio of cotton:clinoptilolite of 2:1), followed by treatment with activated charcoal (AC) and lime, was the best treatment in terms of the quality of water obtained. This treatment decreased concentrations of [Formula: see text] , B, K, P, and total fat in OMW by mean percentages of 78.0, 92.4, 66.6, 48.3, and 93.3%, respectively. Furthermore, it decreased OMW turbidity and electric conductivity (EC) by 96.8 and 48.4%, respectively. Most contaminants were removed from the OMW in the cotton/clinoptilolite column owing to the high sorption affinity of clinoptilolite on its active sites. The AC was efficient for organic particle removal; meanwhile, lime was used to raise the pH of the treated OMW (TOMW) from 2.9 to 5.1. This simple method enables us to obtain environmentally friendly TOMW that can be safely used for irrigation.

Treatment of pretreated coking wastewater by flocculation, alkali out, air stripping, and three-dimensional electrocatalytic oxidation with parallel plate electrodes

The coking wastewater generally comprises highly concentrated, recalcitrant, and toxic organic pollutants, so its treatment has been of great importance to prevent living beings and their environment from these hazardous contaminations. The treatment of pretreated coking wastewater by flocculation-coagulation, alkali out, air stripping, and three-dimensional (3-D) electrocatalytic oxidation was performed (gap between the used β-PbO2/Ti anode and titanium cathode, 12 mm; mass ratio of Cu-Mn/granular activated carbon (GAC) to effluent, 1:4; cell voltage, 7 V). The results showed that the pH adjusting from 3.7 to 6.1 was necessary for coagulants; alkali out played an important role because it brought up precipitation containing higher fatty acids as well as other contaminants to decrease the chemical oxygen demand (COD) in the effluent, and it had also forced the reduction of ammonia nitrogen (NH3-N) by incorporating with air stripping; for 3-D electrocatalytic oxidation with a bleaching liquid assisting, the initial pH 8.5 of effluent was suitable for Cu-Mn/GAC; moreover, it was considered that its Cu component was dedicated to the decrease of COD and NH3-N, while the Mn component specialized in the decay of NH3-N. The residual COD and NH3-N values in the final effluent with pH 6.5 were 95.8 and 8.8 mg/L, respectively, demonstrating that the whole processes applied were feasible and low in cost.

Olive oil mill wastewaters: phenolic content characterization during degradation by Coriolopsis gallica

Olive mill wastewaters (OMW) pose a serious environmental concern owing to high polyphenol content. Decolorization and degradation of phenolic compounds (PC) by Coriolopsis gallica was demonstrated in our laboratory as a potential biotreatment of OMW in solid and liquid media. High performance liquid chromatography coupled to electrospray time-of-flight mass spectrometry was used to analyze the evolution of the main phenolic compounds during the C. gallica biodegradation process. Amongst total the compounds characterized in methanolic extracts of OMW, 12 were unknown, 15 were from different polyphenolic families, and 27 were other non-phenolic compounds. The evolution of PC content during the degradation process indicated that, despite the complexity of the OMW phenolic fraction, C. gallica was able to grow on OMW-based media using PC as sources of carbon and energy, particularly acids, alcohols, lignans and flavones. Complete dephenolization of OMW was obtained.

Application of two bacterial strains for wastewater bioremediation and assessment of phenolics biodegradation

The use of native bacteria is a useful strategy to decontaminate industrial effluents. In this work, two bacterial strains isolated from polluted environments constitutes a promising alternative since they were able to remove several phenolic compounds not only from synthetic solutions but also from effluents derived from a chemical industry and a tannery which are complex matrices. Acinetobacter sp. RTE 1.4 showed ability to completely remove 2-methoxyphenol (1000 mg/L) while Rhodococcus sp. CS 1 not only degrade the same concentration of this compound but also removed 4- chlorophenol, 2,4-dichlorophenol and pentachlorophenol with high efficiency. Moreover, both bacteria degraded phenols naturally present or even exogenously added at high concentrations in effluents from the chemical industry and a tannery in short time (up to 5 d). In addition, a significant reduction of biological oxygen demand and chemical oxygen demand values was achieved after 7 d of treatment for both effluents using Acinetobacter sp. RTE 1.4 and Rhodococcus sp. CS1, respectively. These results showed that Acinetobacter sp. RTE1.4 and Rhodococcus sp. CS 1 might be considered as useful biotechnological tools for an efficient treatment of different effluents, since they showed wide versatility to detoxify these complex matrices, even supplemented with high phenol concentrations.