Special Issue "Environmental Biocatalysis: From Remediation to Waste Valorization"

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Environmental Catalysis".

Deadline for manuscript submissions: closed (15 September 2019).

Special Issue Editors

Dr. Evangelos Topakas
E-Mail Website
Guest Editor
Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, 9 Iroon Polytech Str, Zografou Campus, Athens 15780, Greece
Interests: Industrial Biotechnology; Biocatalysis; Bioremediation Waste valorization; Bioactive compounds; Protein Engineering
Dr. Jasmina Nikodinovic-Runic
E-Mail Website
Guest Editor
Institute of Molecular Genetics and Genetic Engineering (IMGGE), University of Belgrade, 11010 Belgrade, Serbia
Interests: Biocatalysis, Biomaterials, Bacterial polymers, Bioactive molecules

Special Issue Information

Dear Colleagues,

Bioremediation is an attractive bioprocess utilizing microorganisms or their enzymes for the detoxification or even mineralization of xenobiotics. Various enzymatic pathways have been discovered for the conversion of various pollutants, such as polycyclic aromatic hydrocarbons (PAHs), petrochemical polymers, organochlorine insecticides, synthetic dyes and wood preservatives, among others. In the literature, the most-studied enzymatic activities are focused on dehalogenases, mono- or dioxygenases, cytochrome P450 monoxygenases, laccases and peroxidases. The search for novel enzymatic activities that could break down persistent organic pollutants is of the outmost significance, focusing on different extreme environments, a process called bioprospecting. Today, this process has been advanced due to the improvement in omics technologies and synthetic biology, which provide an enormous amount of data available for genome and metagenome mining, as well as the creation of efficient artificial pathways. Novel enzymatic activities may have unique characteristics for the degradation of pollutants, as well as high chemo-, regio- and stereo-selectivity for the modification of aromatic and/or halogenated compounds. Such enzymatic activities will constitute a greener alternative to organic synthesis, providing a mild process with lower energy requirements, while reducing or eliminating the formation of byproducts that might be hazardous to human health and the environment. This Special Issue aims to highlight the dual potential of the novel biocatalytic processes that contribute to the detoxification of pollutants and facilitate the production of high value products such as biologically active compounds. Submissions are welcome in the form of original research papers or short reviews providing a new insight in the area of environmental biocatalysis.

Dr. Evangelos Topakas
Dr. Jasmina Nikodinovic-Runic
Guest Editors

Manuscript Submission Information

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Keywords

  • Biocatalysis
  • Waste valorization
  • Bioremediation
  • Enzyme biocatalysis
  • Whole-cell biocatalysis
  • Persistent organic pollutants
  • Detoxification
  • High-added value compounds
  • Protein engineering
  • Green chemistry

Published Papers (7 papers)

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Research

Open AccessArticle
Identification and Characterization of New Laccase Biocatalysts from Pseudomonas Species Suitable for Degradation of Synthetic Textile Dyes
Catalysts 2019, 9(7), 629; https://doi.org/10.3390/catal9070629 - 23 Jul 2019
Cited by 1
Abstract
Laccases are multicopper-oxidases with variety of biotechnological applications. While predominantly used, fungal laccases have limitations such as narrow pH and temperature range and their production via heterologous protein expression is more complex due to posttranslational modifications. In comparison, bacterial enzymes, including laccases, usually [...] Read more.
Laccases are multicopper-oxidases with variety of biotechnological applications. While predominantly used, fungal laccases have limitations such as narrow pH and temperature range and their production via heterologous protein expression is more complex due to posttranslational modifications. In comparison, bacterial enzymes, including laccases, usually possess higher thermal and pH stability, and are more suitable for expression and genetic manipulations in bacterial expression hosts. Therefore, the aim of this study was to identify, recombinantly express, and characterize novel laccases from Pseudomonas spp. A combination of approaches including DNA sequence analysis, N-terminal protein sequencing, and genome sequencing data analysis for laccase amplification, cloning, and overexpression have been used. Four active recombinant laccases were obtained, one each from P. putida KT2440 and P. putida CA-3, and two from P. putida F6. The new laccases exhibited broad temperature and pH range and high thermal stability, as well as the potential to degrade selection of synthetic textile dyes. The best performing laccase was CopA from P. putida F6 which degraded five out of seven tested dyes, including Amido Black 10B, Brom Cresol Purple, Evans Blue, Reactive Black 5, and Remazol Brilliant Blue. This work highlighted species of Pseudomonas genus as still being good sources of biocatalytically relevant enzymes. Full article
(This article belongs to the Special Issue Environmental Biocatalysis: From Remediation to Waste Valorization)
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Open AccessArticle
Valorization of Olive By-Products as Substrates for the Cultivation of Ganoderma lucidum and Pleurotus ostreatus Mushrooms with Enhanced Functional and Prebiotic Properties
Catalysts 2019, 9(6), 537; https://doi.org/10.3390/catal9060537 - 16 Jun 2019
Abstract
The successful management of olive by-products constitutes a major challenge due to their huge volume, high organic content, and toxicity. Olive-mill wastes (TPOMW) and olive pruning residues (OLPR) were evaluated as substrates for the cultivation of Ganoderma lucidum and Pleurotus ostreatus. Chemical [...] Read more.
The successful management of olive by-products constitutes a major challenge due to their huge volume, high organic content, and toxicity. Olive-mill wastes (TPOMW) and olive pruning residues (OLPR) were evaluated as substrates for the cultivation of Ganoderma lucidum and Pleurotus ostreatus. Chemical composition, glucans, total phenolic content, and antioxidant activity were measured in mushrooms, and their prebiotic potential was assessed by examining their effect on the growth of four intestinal bacteria. Several substrates based on olive by-products had a positive impact on P. ostreatus mushroom production, whereas only one performed adequately for G. lucidum. Increased ratios of OLPR to wheat-straw resulted in an increase of crude protein content in P. ostreatus fruit-bodies by up to 42%, while G. lucidum mushrooms from OLPR-based substrates exhibited an up to three-fold increase in α-glucan, or a significant enhancement of β-glucan content, when compared to beech sawdust (control). The mushrooms’ FTIR spectra confirmed the qualitative/quantitative differentiation detected by standard assays. In regard to prebiotic properties, mushrooms powder supported or even enhanced growth of both Lactobacillus acidophilus and L. gasseri after 24/48 h of incubation. In contrast, a strain-specific pattern was observed in bifidobacteria; mushrooms hindered Bifidobacterium bifidum growth, whereas they supported a similar-to-glucose growth for B. longum. Full article
(This article belongs to the Special Issue Environmental Biocatalysis: From Remediation to Waste Valorization)
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Open AccessArticle
Nitrogen Removal by Co-Immobilized Anammox and Ammonia-Oxidizing Bacteria in Wastewater Treatment
Catalysts 2019, 9(6), 523; https://doi.org/10.3390/catal9060523 - 12 Jun 2019
Abstract
In wastewater treatment, an alternative to the widely used aerobic nitrification with subsequent anoxic denitrification method is the combination of nitration and anammox (AMX) in one system. This study focuses on the co-immobilization of AMX and ammonia-oxidizing bacteria into a polyvinyl alcohol (PVA) [...] Read more.
In wastewater treatment, an alternative to the widely used aerobic nitrification with subsequent anoxic denitrification method is the combination of nitration and anammox (AMX) in one system. This study focuses on the co-immobilization of AMX and ammonia-oxidizing bacteria into a polyvinyl alcohol (PVA) hydrogel, and its effective use in nitrogen removal (NR). The NR process was performed in nine consecutive, repeated batches. By optimizing the conditions of the biotransformations, there was equal utilization of nitrogen in both sources, N–NH4+ and N–NO2, at 100% NR during the sixth repetition. A significant increase in the immobilized co-culture activity was also detected per cycle. The maximum value of the NR rate was 3.46 mg N (L h)−1, and 100% NR efficiency was achieved with an initial concentration of 100.3 mg N L−1 for N–NH4+ and 60.1 mg N L−1 for N–NO2, during the eighth batch biotransformation. Full article
(This article belongs to the Special Issue Environmental Biocatalysis: From Remediation to Waste Valorization)
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Open AccessArticle
Influence of Chemical Modifications of Polyhydroxyalkanoate-Derived Fatty Acids on Their Antimicrobial Properties
Catalysts 2019, 9(6), 510; https://doi.org/10.3390/catal9060510 - 05 Jun 2019
Abstract
Sugar esters are bioactive compounds derived from renewable resources. They consist of a sugar moiety with attached non-polar part – usually a fatty acid. These compounds find uses in cosmetic, food and pharmaceutical industries as surfactants due to their physicochemical and antimicrobial activities. [...] Read more.
Sugar esters are bioactive compounds derived from renewable resources. They consist of a sugar moiety with attached non-polar part – usually a fatty acid. These compounds find uses in cosmetic, food and pharmaceutical industries as surfactants due to their physicochemical and antimicrobial activities. In this study we have produced fatty acids for sugar ester synthesis from bacterially derived polyesters, namely polyhydroxyalkanoates (PHAs). We have developed methodology to decorate PHA monomers with a fluorinated moiety. With aid of biocatalysis a series of glucose esters was created with unmodified and modified PHA monomers. All synthesised compounds showed moderate antimicrobial activity. Full article
(This article belongs to the Special Issue Environmental Biocatalysis: From Remediation to Waste Valorization)
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Open AccessArticle
High Cell Density Conversion of Hydrolysed Waste Cooking Oil Fatty Acids Into Medium Chain Length Polyhydroxyalkanoate Using Pseudomonas putida KT2440
Catalysts 2019, 9(5), 468; https://doi.org/10.3390/catal9050468 - 21 May 2019
Cited by 1
Abstract
Waste cooking oil (WCO) is a major pollutant, primarily managed through incineration. The high cell density bioprocess developed here allows for better use of this valuable resource since it allows the conversion of WCO into biodegradable polymer polyhydroxyalkanoate (PHA). WCO was chemically hydrolysed [...] Read more.
Waste cooking oil (WCO) is a major pollutant, primarily managed through incineration. The high cell density bioprocess developed here allows for better use of this valuable resource since it allows the conversion of WCO into biodegradable polymer polyhydroxyalkanoate (PHA). WCO was chemically hydrolysed to give rise to a mixture of fatty acids identical to the fatty acid composition of waste cooking oil. A feed strategy was developed to delay the stationary phase, and therefore achieve higher final biomass and biopolymer (PHA) productivity. In fed batch (pulse feeding) experiments Pseudomonas putida KT2440 achieved a PHA titre of 58 g/l (36.4% of CDW as PHA), a PHA volumetric productivity of 1.93 g/l/h, a cell density of 159.4 g/l, and a biomass yield of 0.76 g/g with hydrolysed waste cooking oil fatty acids (HWCOFA) as the sole substrate. This is up to 33-fold higher PHA productivity compared to previous reports using saponified palm oil. The polymer (PHA) was sticky and amorphous, most likely due to the long chain monomers acting as internal plasticisers. High cell density cultivation is essential for the majority of industrial processes, and this bioprocess represents an excellent basis for the industrial conversion of WCO into PHA. Full article
(This article belongs to the Special Issue Environmental Biocatalysis: From Remediation to Waste Valorization)
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Open AccessArticle
Expression and Characterization of a Dye-Decolorizing Peroxidase from Pseudomonas Fluorescens Pf0-1
Catalysts 2019, 9(5), 463; https://doi.org/10.3390/catal9050463 - 20 May 2019
Abstract
The consumption of dyes is increasing worldwide in line with the increase of population and demand for clothes and other colored products. However, the efficiency of dyeing processes is still poor and results in large amounts of colored effluents. It is desired to [...] Read more.
The consumption of dyes is increasing worldwide in line with the increase of population and demand for clothes and other colored products. However, the efficiency of dyeing processes is still poor and results in large amounts of colored effluents. It is desired to develop a portfolio of enzymes which can be used for the treatment of colored wastewaters. Herein, we used genome sequence information to discover a dye-decolorizing peroxidase (DyP) from Pseudomonas fluorescens Pf-01. Two genes putatively encoding for DyPs were identified in the respective genome and cloned for expression in Escherichia coli, of which one (PfDyP B2) could be overexpressed as a soluble protein. PfDyP B2 shows some typical features known for DyPs which includes the ability to convert dyes at the expense of hydrogen peroxide. Interestingly, t-butyl hydroperoxide could be used as an alternative substrate to hydrogen peroxide. Immobilization of PfDyP B2 in calcium-alginate beads resulted in a significant increase in stability: PfDyP B2 retains 80% of its initial activity after 2 h incubation at 50 °C, while the soluble enzyme is inactivated within minutes. PfDyP B2 was also tested with aniline and ethyl diazoacetate as substrates. Based on GC-MS analyses, 30% conversion of the starting material was achieved after 65 h at 30 °C. Importantly, this is the first report of a DyP-catalyzed insertion of a carbene into an N-H bond. Full article
(This article belongs to the Special Issue Environmental Biocatalysis: From Remediation to Waste Valorization)
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Open AccessArticle
Microalgae Cultivation for the Biotransformation of Birch Wood Hydrolysate and Dairy Effluent
Catalysts 2019, 9(2), 150; https://doi.org/10.3390/catal9020150 - 02 Feb 2019
Abstract
In order to investigate environmentally sustainable sources of organic carbon and nutrients, four Nordic green microalgal strains, Chlorella sorokiniana, Chlorella saccharophila, Chlorella vulgaris, and Coelastrella sp., were grown on a wood (Silver birch, Betula pendula) hydrolysate and dairy effluent mixture. [...] Read more.
In order to investigate environmentally sustainable sources of organic carbon and nutrients, four Nordic green microalgal strains, Chlorella sorokiniana, Chlorella saccharophila, Chlorella vulgaris, and Coelastrella sp., were grown on a wood (Silver birch, Betula pendula) hydrolysate and dairy effluent mixture. The biomass and lipid production were analysed under mixotrophic, as well as two-stage mixotrophic/heterotrophic regimes. Of all of the species, Coelastrella sp. produced the most total lipids per dry weight (~40%) in the mixture of birch hydrolysate and dairy effluent without requiring nutrient (nitrogen, phosphorus, and potassium—NPK) supplementation. Overall, in the absence of NPK, the two-stage mixotrophic/heterotrophic cultivation enhanced the lipid concentration, but reduced the amount of biomass. Culturing microalgae in integrated waste streams under mixotrophic growth regimes is a promising approach for sustainable biofuel production, especially in regions with large seasonal variation in daylight, like northern Sweden. To the best of our knowledge, this is the first report of using a mixture of wood hydrolysate and dairy effluent for the growth and lipid production of microalgae in the literature. Full article
(This article belongs to the Special Issue Environmental Biocatalysis: From Remediation to Waste Valorization)
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