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1.
Braz. J. Biol. ; 83: 1-8, 2023. graf
Artigo em Inglês | VETINDEX, VETINDEX | ID: vti-765419

RESUMO

Poultry industry is expanding rapidly and producing million tons of feather waste annually. Massive production of keratinaceous byproducts in the form of industrial wastes throughout the world necessitates its justified utilization. Chemical treatment of keratin waste is proclaimed as an eco-destructive approach by various researchers since it generates secondary pollutants. Keratinase released by a variety of microbes (bacteria and fungi) can be used for the effective treatment of keratin waste. Microbial degradation of keratin waste is an emerging and eco-friendly approach and offers dual benefits, i.e., treatment of recalcitrant pollutant (keratin) and procurement of a commercially important enzyme (keratinase). This study involves the isolation, characterization, and potential utility of fungal species for the degradation of chicken-feather waste through submerged and solid-state fermentation. The isolated fungus was identified and characterized as Aspergillus (A.) flavus. In a trial of 30 days, it was appeared that 74 and 8% feather weight was reduced through sub-merged and solid-state fermentation, respectively by A. flavus. The pH of the growth media in submerged fermentation was changed from 4.8 to 8.35. The exploited application of keratinolytic microbes is, therefore, recommended for the treatment of keratinaceous wastes to achieve dual benefits of remediation.(AU)


A indústria avícola está se expandindo rapidamente e produzindo milhões de toneladas de resíduos de penas anualmente. A produção massiva de subprodutos queratinosos na forma de resíduos agrícolas e industriais em todo o mundo exige sua utilização justificada. O tratamento químico de resíduos de queratina é proclamado como uma abordagem ecodestrutiva por vários pesquisadores, uma vez que gera poluentes secundários. A queratinase liberada por uma variedade de micróbios (bactérias e fungos) pode ser usada para o tratamento eficaz de resíduos de queratina. A degradação microbiana de resíduos de queratina é uma abordagem emergente e ecológica e oferece benefícios duplos, ou seja, tratamento de poluente recalcitrante (queratina) e obtenção de uma enzima comercialmente importante (queratinase). Este estudo envolve o isolamento, caracterização e utilidade potencial de espécies de fungos para a degradação de resíduos de penas de frango por meio da fermentação submersa e em estado sólido. O fungo isolado foi identificado e caracterizado como Aspergillus (A.) flavus. Em um ensaio de 30 dias, constatou-se que 74% e 8% do peso das penas foram reduzidos por A. flavus, respectivamente, por meio da fermentação submersa e em estado sólido. O pH do meio de crescimento em fermentação submersa foi alterado de 4,8 para 8,35. A aplicação explorada de micróbios queratinolíticos é, portanto, recomendada para o tratamento de resíduos ceratinosos para obter benefícios duplos de remediação.(AU)


Assuntos
Aspergillus flavus/isolamento & purificação , Queratinas/análise , Queratinas/toxicidade , Biotransformação
2.
Braz. j. biol ; 83: e246389, 2023. graf
Artigo em Inglês | MEDLINE, LILACS, VETINDEX | ID: biblio-1285638

RESUMO

Abstract Poultry industry is expanding rapidly and producing million tons of feather waste annually. Massive production of keratinaceous byproducts in the form of industrial wastes throughout the world necessitates its justified utilization. Chemical treatment of keratin waste is proclaimed as an eco-destructive approach by various researchers since it generates secondary pollutants. Keratinase released by a variety of microbes (bacteria and fungi) can be used for the effective treatment of keratin waste. Microbial degradation of keratin waste is an emerging and eco-friendly approach and offers dual benefits, i.e., treatment of recalcitrant pollutant (keratin) and procurement of a commercially important enzyme (keratinase). This study involves the isolation, characterization, and potential utility of fungal species for the degradation of chicken-feather waste through submerged and solid-state fermentation. The isolated fungus was identified and characterized as Aspergillus (A.) flavus. In a trial of 30 days, it was appeared that 74 and 8% feather weight was reduced through sub-merged and solid-state fermentation, respectively by A. flavus. The pH of the growth media in submerged fermentation was changed from 4.8 to 8.35. The exploited application of keratinolytic microbes is, therefore, recommended for the treatment of keratinaceous wastes to achieve dual benefits of remediation.


Resumo A indústria avícola está se expandindo rapidamente e produzindo milhões de toneladas de resíduos de penas anualmente. A produção massiva de subprodutos queratinosos na forma de resíduos agrícolas e industriais em todo o mundo exige sua utilização justificada. O tratamento químico de resíduos de queratina é proclamado como uma abordagem ecodestrutiva por vários pesquisadores, uma vez que gera poluentes secundários. A queratinase liberada por uma variedade de micróbios (bactérias e fungos) pode ser usada para o tratamento eficaz de resíduos de queratina. A degradação microbiana de resíduos de queratina é uma abordagem emergente e ecológica e oferece benefícios duplos, ou seja, tratamento de poluente recalcitrante (queratina) e obtenção de uma enzima comercialmente importante (queratinase). Este estudo envolve o isolamento, caracterização e utilidade potencial de espécies de fungos para a degradação de resíduos de penas de frango por meio da fermentação submersa e em estado sólido. O fungo isolado foi identificado e caracterizado como Aspergillus (A.) flavus. Em um ensaio de 30 dias, constatou-se que 74% e 8% do peso das penas foram reduzidos por A. flavus, respectivamente, por meio da fermentação submersa e em estado sólido. O pH do meio de crescimento em fermentação submersa foi alterado de 4,8 para 8,35. A aplicação explorada de micróbios queratinolíticos é, portanto, recomendada para o tratamento de resíduos ceratinosos para obter benefícios duplos de remediação.


Assuntos
Animais , Galinhas , Plumas , Fermentação , Fungos , Resíduos Industriais , Queratinas/metabolismo
3.
Front Microbiol ; 13: 840562, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35369425

RESUMO

Antibiotic resistance is one of the most important environmental challenges. Microalgae has been considered as a promising green media for environmental purification. In this work, sulfadimethoxine (SDM) biodegradation potential of Chlorella sp. L38 and Phaeodactylum tricornutum MASCC-0025 is investigated. Experimental results indicated that the tested freshwater and marine microalgae strains presented stress response to SDM addition. For Chlorella sp. L38, it has a good adaptability to SDM condition via antioxidant enzyme secretion (SOD, MDA, and CAT up to 23.27 U/mg, 21.99 µmol/g, and 0.31 nmol/min/mg) with removal rate around 88%. P. tricornutum MASCC-0025 exhibited 100% removal of 0.5 mg/L SDM. With increasing salinity (adding a certain amount of NaCl) of cultivation media, the removal rate of SDM by microalgae increased. Although its adaptive process was slower than Chlorella sp. L38, the salinity advantage would facilitate enzyme accumulation. It indicated that microalgae could be used to remove SDM from freshwater and marine environment via suitable microalgae strain screening.

4.
Artigo em Inglês | MEDLINE | ID: mdl-35532825

RESUMO

Low-density polyethylene (LDPE), biaxially oriented polypropylene (BOPP), and expanded polystyrene (EXPS) are the most common plastics found in every home of the world, but only ~ 10% enter the recycling chains. Consequently, the study of plastic biodegradation by microorganisms and insects, such as the wax moths, has gained special interest. Galleria mellonella (L.) has been shown to consume single-layered polyethylene and polystyrene, though biological impacts of this consumption have been rarely reported. We evaluated the consumption of different plastics by G. mellonella larvae (L7, mean size: 25-30 mm) and its effect on larval duration, survival, and development. For this, we offered the larvae five diets: single-layered LDPE, EXPS, BOPP, triple-layered polyethylene (SB, for silo-bags), and a control with beeswax. We recorded the state and weight of the materials and the state of larvae until they reached the adult stage. Larvae consumed more PE (both LDPE and SB) and EXPS than BOPP; still, they were able to emerge as adults in all treatments. Larvae that consumed plastics turned into pupal stage faster than those that consumed beeswax, regardless of the type and amount of plastic consumed. This is the first report of wild G. mellonella larvae in Argentina consuming biaxially polypropylene and silo-bags.

5.
World J Microbiol Biotechnol ; 38(6): 105, 2022 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-35501608

RESUMO

The pollution of water resources by pesticides poses serious problems for public health and the environment. In this study, Actinobacteria strains were isolated from three wastewater treatment plants (WWTPs) and were screened for their ability to degrade 17 pesticide compounds. Preliminary screening of 13 of the isolates of Actinobacteria allowed the selection of 12 strains with potential for the degradation of nine different pesticides as sole carbon source, including aliette, for which there are no previous reports of biodegradation. Evaluation of the bacterial growth and degradation kinetics of the pesticides 2,4-dichlorophenol (2,4-DCP) and thiamethoxam (tiam) by selected Actinobacteria strains was performed in liquid media. Strains Streptomyces sp. ML and Streptomyces sp. OV were able to degrade 45% of 2,4-DCP (50 mg/l) as the sole carbon source in 30 days and 84% of thiamethoxam (35 mg/l) in the presence of 10 mM of glucose in 18 days. The biodegradation of thiamethoxam by Actinobacteria strains was reported for the first time in this study. These strains are promising for use in bioremediation of ecosystems polluted by this type of pesticides.


Assuntos
Actinobacteria , Praguicidas , Streptomyces , Purificação da Água , Actinobacteria/metabolismo , Argélia , Carbono/metabolismo , Ecossistema , Praguicidas/metabolismo , Streptomyces/metabolismo , Tiametoxam/metabolismo
6.
Front Bioeng Biotechnol ; 10: 854298, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35519608

RESUMO

The outstanding metabolic and bioprotective properties of the bacterial genus Pseudomonas make these species a potentially interesting source for the search of hydrolytic activities that could be useful for the degradation of plastics. We identified two genes encoding the intracellular lipases LIP1 and LIP2 of the biocontrol bacterium Pseudomonas chlororaphis PA23 and subsequently performed cloning and expression in Escherichia coli. The lip1 gene has an open reading frame of 828 bp and encodes a protein of 29.7 kDa whereas the lip2 consists of 834 bp and has a protein of 30.2 kDa. Although secondary structure analyses of LIP1 and LIP2 indicate a dominant α/ß-hydrolase-fold, the two proteins differ widely in their amino acid sequences (15.39% identity), substrate specificities, and hydrolysis rates. Homology modeling indicates the catalytic serine in both enzymes located in a GXSXG sequence motif (lipase box). However, LIP1 has a catalytic triad of Ser152-His253-Glu221 with a GGX-type oxyanion pocket, whereas LIP2 has Ser138-His249-Asp221 in its active site and a GX-type of oxyanion hole residues. However, LIP1 has a catalytic triad of Ser152-His253-Glu221 with an oxyanion pocket of GGX-type, whereas LIP2 has Ser138-His249-Asp221 in its active site and a GX-type of oxyanion hole residues. Our three-dimensional models of LIP1 and LIP2 complexed with a 3-hydroxyoctanoate dimer revealed the core α/ß hydrolase-type domain with an exposed substrate binding pocket in LIP1 and an active-site capped with a closing lid domain in LIP2. The recombinant LIP1 was optimally active at 45°C and pH 9.0, and the activity improved in the presence of Ca2+. LIP2 exhibited maximum activity at 40°C and pH 8.0, and was unaffected by Ca2+. Despite different properties, the enzymes exhibited broadsubstrate specificity and were able to hydrolyze short chain length and medium chain length polyhydroxyalkanoates (PHAs), polylactic acid (PLA), and para-nitrophenyl (pNP) alkanoates. Gel Permeation Chromatography (GPC) analysis showed a decrease in the molecular weight of the polymers after incubation with LIP1 and LIP2. The enzymes also manifested some polymer-degrading activity on petroleum-based polymers such as poly(ε-caprolactone) (PCL) and polyethylene succinate (PES), suggesting that these enzymes could be useful for biodegradation of synthetic polyester plastics. The study will be the first report of the complete characterization of intracellular lipases from bacterial and/or Pseudomonas species. The lipases, LIP1 and LIP2 are different from other bacterial lipases/esterases in having broad substrate specificity for polyesters.

7.
Ecotoxicol Environ Saf ; 238: 113605, 2022 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-35561546

RESUMO

The analysis of soil bacterial community has guiding significance for fully utilization of soil microbial resources. The results of high-throughput sequencing (HTS) showed that the bacteria in the three sulfometuron-methyl contaminated soil samples were mainly composed of 677 genera, including Phenylobacterium, Bacillus, belonging to 28 phyla, including Proteobacteria, Firmicutes. The diversity and richness of bacterial community decreased with the increase in sulfometuron-methyl concentration. In addition, sulfometuron-methyl could also affect the soil bacterial function based on PICRUSt functional predictive analysis. Combined with the results of HTS and phylogenetic molecular ecological networks (pMENs), 12 genera, including Ralstonia (Pi=0.64), were identified as the key soil microflora (intra-module connectivity Zi ≥ 2.5 or inter-module connectivity Pi ≥ 0.62), and the abundance of Ralstonia significantly increased with the concentration of sulfometuron-methyl, indicating that the strains of this genus might be the potential degrading bacteria and could form a stable relationship with indigenous microorganisms. Among the isolated bacteria of genus Ralstonia, one strain, named Ralstonia sp. JM-1, was verified to possess higher sulfometuron-methyl degradation efficiency, which completely degraded 20 mg L-1 of sulfometuron-methyl within 96 h. Furthermore, the immobilized strains generated by the mixture of 2.0 g bamboo charcoal and 3.0 mL bacterial suspension for 24 h had the highest sulfometuron-methyl degradation rate than that under other conditions, and the dynamic process degrading 10-30 mg L-1 of sulfometuron-methyl conforms to the zero-order kinetic equation. The bioremediation of contaminated soil showed the immobilized strains could completely degrade sulfometuron-methyl (1.39 mg kg-1) in contaminated soil within 9 d, which is higher than that application of strains in the free state (74.8%). This study could provide ideas for the isolation of functional strains and a theoretical basis for the bioremediation of STM and other contaminated soils.

8.
Chemosphere ; : 134935, 2022 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-35561776

RESUMO

In this work, Rhodococcus ruber HJM-8 and Paracoccus communis YBH-X were isolated and used to enhance N,N-dimethylacetamide (DMAC) degradation and mineralization efficiencies. The monoculture and co-culture of the two strains for DMAC degradation were compared; results indicated that, a degradation efficiency of 97.62% was obtained in co-culture, which was much higher than that of monocultures of HJM-8 (57.34%) and YBH-X (34.02%). The degradation mechanism showed that co-culture could efficiently improve extracellular polymeric substances production, electron transfer, and microbial activity. Meanwhile, the mineralization mechanism suggested that acetate was the dominant intermediate which had an inhibitory effect on HJM-8, and co-culture was conducive to mineralization due to the high performance of acetate conversion and Na+ K+-ATPase vitality. Besides, a pathway of DMAC biodegradation was proposed for co-culture: DMAC was degraded into acetate by HJM-8, then the accumulated acetate was mineralized by YBH-X. Additionally, the co-culture system was further optimized by Box-Behnken design.

9.
Environ Pollut ; : 119452, 2022 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-35561799

RESUMO

The social and ecological influence of Neonicotinoids (NEOs) usage in agriculture sector is progressively higher. There are seven NEOs insecticides widely used for insect control. Among the NEOs, thiacloprid (THD) was extensively used for insect control during crop cultivation. This study targets to analyse the contamination levels of NEOs in agricultural soil and identify photo-biodegradation of THD degradation using pure isolates and mixed consortium. The photo degradation (PD), biodegradation (BD) and photo-biodegradation (PBD) of THD were compared. The corn field agricultural soils were polluted by four NEOs, among them THD had greater contamination level (surface soil: 3901.2 ±â€¯0.04 µg/g) and (sub-surface soil: 3988.6 ±â€¯0.05 µg/g). Three soil free enriched bacterial strains following Bacillus atrophaeus (PB-2), Priestia megaterium (PB-3) (formerly known as Bacillus megaterium), and Peribacillus simplex (PB-4) (formerly known as Bacillus simplex) were identified by microbiological and molecular 16s rRNA gene sequencing. The PD, BD and PBD of THD were conducted and degradation rate was detected by instrument UPLC-MS-MS. The PBD process with blue-LEDs showed better THD degradation efficiency than PD and BD, where the specific THD degradation rate was 85 ±â€¯0.2%, 87 ±â€¯0.5%, and 89 ±â€¯0.3%, respectively for PB-2, PB-3 and PB-4. Then, the photo-biodegradation performance is greater at 150, 175, 200 rpm, pH 7.0-9.0, and temperature 30-35 °C. After the PBD system deliver four intermediate metabolites, the THD degradation process maybe through nitro reduction, hydroxylation and oxidative cleavage pathway.

10.
3 Biotech ; 12(5): 120, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35547016

RESUMO

Streptomyces chilikensis RC1830 was previously isolated as a novel chitinolytic streptomycete from Chilika Lake, Odisha, India. The strain RC1830 is a representative member of the soil-dwelling, filamentous Streptomyces group that produces the majority of natural antibiotics and secondary metabolites. The objective of this work was to assess the chitin degradation ability and whole-genome sequence of Streptomyces chilikensis RC1830. TLC analysis of the fermentation product revealed that strain RC1830 can convert shrimp shell colloidal chitin to N-acetylated chitooligosaccharides (N-AcCOS). A genome-wide investigation of RC1830 was also carried out to investigate the genetic basis for chitin breakdown. The result showed that the RC1830 genome possesses a chromosome with 7,121,774 bp (73.2% GC). The genome consists of 6807 coding sequences, 69 tRNA, and 3 rRNA genes. Furthermore, carbohydrate-active enzyme (CAZyme) analysis revealed that RC1830 has 89 glycoside hydrolase family genes, which could modulate the enzymes involved in the degradation of chitin ultimately producing industrially important COS. The whole-genome information of RC1830 could emphasize the mechanism involved in the RC1830's chitin breakdown activity, endowing RC1830 with a promising alternative for COS production. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-022-03184-5.

11.
Environ Pollut ; : 119453, 2022 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-35569624

RESUMO

In this study, Bacillus sp. strain AVPP64 was isolated from diuron-contaminated soil. It showed 4-Nitroaniline (4-NA) degradation, pesticide tolerance, and self-nutrient integration via nitrogen (N)-fixation and phosphate (P)-solubilization. The rate constant (k) and half-life period (t1/2) of 4-NA degradation in the aqueous medium inoculated with strain AVPP64 were observed to be 0.445 d-1 and 1.55 d, respectively. Nevertheless, in the presence of chlorpyrifos, profenofos, atrazine and diuron pesticides, strain AVPP64 degraded 4-NA with t1/2 values of 2.55 d, 2.26 d, 2.31 d and 3.54 d, respectively. The strain AVPP64 fixed 140 µg mL-1 of N and solubilized 103 µg mL-1 of P during the presence of 4-NA. In addition, strain AVPP64 produced significant amounts of plant growth-promoting metabolites like indole 3-acetic acid, siderophores, exo-polysaccharides and ammonia. In the presence of 4-NA and various pesticides, strain AVPP64 greatly increased the growth and biomass of Vigna radiata and Crotalaria juncea plants. These results revealed that Bacillus sp. strain AVPP64 can be used as an inoculum for bioremediation of 4-NA contaminated soil and sustainable crop production even when pesticides are present.

12.
Artigo em Inglês | MEDLINE | ID: mdl-35576038

RESUMO

Pollution of aquatic ecosystems with nonylphenol (NP) and butyltins (BuTs) is of great concern due to their effects on endocrine activity, toxicity to aquatic organisms, and extended persistence in sediments. The impact of contamination with NP and/or BuTs on the microbial community structure in marine sediments was investigated using microcosms and high-throughput sequencing. Sediment microcosms with NP (300 mg/kg) and/or BuTs (95 mg/kg) were constructed. Complete removal of monobutyltin (MBT) occurred in the microcosms after 240 days of incubation, while a residual NP rate was 40%. The content of toxic tributyltin (TBT) and dibutyltin (DBT) in the sediments did not change notably. Co-contamination of the sediments with NP and BuTs did not affect the processes of their degradation. The pollutants in the microcosms could have been biodegraded by autochthonous microorganisms. Significantly different and less diverse bacterial communities were observed in the contaminated sediments compared to non-contaminated control. Firmicutes and Gammaproteobacteria dominated in the NP treatment, Actinobacteria and Alphaproteobacteria in the BuT treatment, and Gammaproteobacteria, Alphaproteobacteria, Firmicutes, and Acidobacteria in the NP-BuT mixture treatment. The prevalence of microorganisms from the bacterial genera Halothiobacillus, Geothrix, Methanosarcina, Dyella, Parvibaculum, Pseudomonas, Proteiniclasticum, and bacteria affiliated with the order Rhizobiales may indicate their role in biodegradation of NP and BuTs in the co-contaminated sediments. This study can provide some new insights towards NP and BuT biodegradation and microbial ecology in NP-BuT co-contaminated environment.

13.
Foods ; 11(9)2022 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-35563917

RESUMO

Zearalenone (ZEN) is produced by Fusarium spp. and is widely found in moldy wheat, corn, and other grains. ZEN has a strong toxicity and causes reproductive and immune disorders and estrogenic syndrome in animals and humans. Biodegradation has been demonstrated as an efficient way to control the hazardous effect of ZEN. A promising way to apply biodegradation in feed is to introduce anaerobic ZEN-degrading microorganisms, which can function during the digestion process in animal intestines. The aim of this study was to isolate anaerobic ZEN-degrading bacteria from anaerobic environments. A strain named F39 was isolated from animal intestinal contents and had a ZEN-degradation rate of 87.35% in 48 h to form trace amount of α- and ß-zearalenol. Based on the morphological and physiological properties and phylogenetic analysis of 16S rRNA and rpoB gene sequences, F39 was identified as Clostridium sporogenes. The optimum temperature for the growth of F39 was 37 °C, the optimum pH was 7.0, and the most suitable carbon source was beef extract, while the optimal conditions for the degradation of ZEN were as follows: 35 °C, pH 7.0, and GAM medium. ZEN was degraded by F39 with a high efficiency in the concentration range of 1-15 mg/L. The bioactive factors responsible for ZEN degradation were mainly distributed intracellularly. F39 can degrade most of the ZEN present, but a small amount is broken down into two secondary metabolites, α- and ß-zearalenol, and the toxicity of the degradation products is reduced. With an efficiency of 49%, F39 can more effectively degrade ZEN in wheat-based feedstuffs than in other feedstuff, and the degradation efficiency was pH related. To the best of our knowledge, this is the first report of Clostridium sporogenes F39's ability to maintain the biodegradation potentials.

14.
Chemosphere ; 301: 134777, 2022 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-35500629

RESUMO

Groundwater pollution has increased in recent years due to the intensification of agricultural and livestock activities. This results in a significant reduction in available freshwater resources. Here, we have studied the long term assessment of a green technology (1-4 L/day) based on a photobioreactor (PBR) containing immobilised microalgae-bacteria in polyurethane foam (PF) followed by a cork filter (CF) for removing nitrates, pesticides (atrazine and bromacil), and antibiotics (sulfamethoxazole and sulfacetamide) from groundwater. The prototype was moderately effective for removing nitrates (58%) at an HRT of 8 days, while its efficiency decreased at a HRT of 4 and 2 days (<20% removal). The combined use of PBR-CF enabled antibiotics and pesticides to be attenuated by up to 95% at an HRT of 8 days, but their attenuation decreased with shorter HRT, with pesticides being the compounds most affected (reducing from 97 to 98% at an HRT of 8 days to 23-45% at an HRT of 2 days). Pesticide transformation products were identified after the CF, supporting biodegradation as the main attenuation process. A gene-based metataxonomic assessment linked the attenuation of micropollutants to the presence of specific pesticide biodegradation species (e.g. genus Phenylobacterium, Sphingomonadaceae, and Caulobacteraceae). Therefore, the results highlighted the potential use of microalgae and cork to treat polluted groundwater.

15.
Environ Pollut ; 306: 119384, 2022 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-35504349

RESUMO

Polycyclic aromatic hydrocarbons (PAHs) are hazardous toxic contaminants and considered as primary pollutants due to their persistent nature and most of them are carcinogenic and mutagenic. The key challenge in PAHs degradation is their hydrophobic nature, which makes them one of the most complex materials and inaccessible by a broad range of microorganisms. This bioavailability can be increased by using a biosurfactant. In the present study mixed PAHs were degraded using the biosurfactant producing bacterial strains. In addition, iron nanoparticles were synthesized and the impact of iron nanoparticles on the growth of the mixed bacterial strains (Pseudomonas stutzeri NA3 and Acinetobacter baumannii MN3) was optimized. The mixed PAHs (anthracene, pyrene, and benzo(a)pyrene) degradation was enhanced by addition of biosurfactant (produced by Bacillus subtilis A1) and iron nanoparticles, resulting in 85% of degradation efficiency. The addition of the biosurfactant increased the bioavailability of the PAHs in the aqueous environment, which might help bacterial cells for the initial settlement and development. The addition of iron nanoparticles increased both bacterial biomass and PAHs adsorption over their surface. These overall interactions assisted in the utilization of PAHs by the mixed bacterial consortia. This study illustrates that this integrated approach can be elaborated for the removal of the complex PAHs pollutants from soil and aqueous environments.

16.
Environ Pollut ; 306: 119382, 2022 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-35525509

RESUMO

Glyphosate (N-phosphonomethylglycine; GLP) and its main metabolite AMPA (aminomethylphosphonic acid), are frequently detected in relatively high concentrations in European agricultural topsoils. Glyphosate has a high sorption affinity, yet it can be detected occasionally in groundwater. We hypothesized that shrinkage cracks occurring after dry periods could facilitate GLP transport to greater depths where subsoil conditions slow further microbial degradation. To test this hypothesis, we simulated a heavy rainfall event (HRE) on a clay-rich arable soil. We applied 2.1 kg ha-1 of 100% 13C3, 15N-labeled GLP one day before the simulated rainfall event. Microbial degradation of translocated GLP over a 21-day period was assessed by quantifying 13C incorporation into phospholipid fatty acids. Microbial degradation potential and activity were determined by quantifying the abundance and expression of functional genes involved in the two known degradation pathways of GLP; to AMPA (goxA) or sarcosine (sarc). We confirmed that goxA transcripts were elevated in the range of 4.23 x 105 copy numbers g-1 soil only one day after application. The increase in AMPA associated with a rise in goxA transcripts and goxA-harboring microorganisms indicated that the degradation pathway to AMPA dominated. Based on 13C-enrichment 3 h after the HRE, fungi appeared to initiate glyphosate degradation. At later time points, Gram+-bacteria proved to be the main degraders due to their higher 13C-incorporation. Once GLP reached the subsoil, degradation continued but more slowly. By comparing GLP distribution and its microbial degradation in macropores and in the bulk soil, we demonstrated different time- and depth-dependent GLP degradation dynamics in macropores. This indicates the need for field studies in which soil properties relevant to GLP degradation are related to limiting environmental conditions, providing a realistic assessment of GLP fate in soils.

17.
Sci Total Environ ; 837: 155719, 2022 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-35526626

RESUMO

Larvae of superworms (Zophobas atratus Fab.) and yellow mealworms (Tenebrio molitor Linn.) can survive on sole plastic diets. However, no side-by-side comparison of plastics degradation by both species is available yet. Here, superworms and yellow mealworms were fed with polystyrene (PS) or polyurethane (PU) foam plastics as sole diets for 35 days with bran as control. Superworms survived 100% on all diets but decreased weights were observed after 20 days with sole plastic diets. In contrast, yellow mealworms survived 84.67% or 62.67% with PS or PU diet, respectively, both plastics diet groups showed increased weights. Cumulative consumption of plastics by superworms were 49.24 mg-PS/larva and 26.23 mg-PU/larva, which were 18 and 11 folds of that of yellow mealworms, respectively. When converted into mg/g-larvae, superworms had a higher PS consumption rate but both species had similar PU consumption rates. Similar changes of the plastic chemical functional groups in frass indicated occurrences of oxidation and biodegradation of plastics in the guts of both species. Changes of gut microbial communities were found associated with plastics feedstocks and larvae species. The increased relative abundances of unclassified Enterobacteriaceae, Klebsiella, Enterococcus, Dysgonomonas and Sphingobacterium were strongly associated with PS diet in superworms, while Hafnia was strongly associated with PS diet in yellow mealworms. Enterococcus and Mangrovibacter were dominant in PU-fed superworm guts, while unclassified Enterobacteriaceae and Hafnia were strongly associated with PU feeding in yellow mealworms. The results demonstrated that different plastics ingestion preferences and efficiencies of both species were associated with distinct dominant microbiomes although similar changes of chemical groups in plastics were observed.

18.
Sci Total Environ ; 837: 155744, 2022 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-35526632

RESUMO

A remediation strategy using three non-toxic availability enhancers (two cyclodextrins and a rhamnolipid biosurfactant) was applied to various soils artificially contaminated with a mix of Polycyclic Aromatic Hydrocarbons (PAHs) considered priority pollutants at two levels of contamination: only with 7 low molecular weight PAHs (LMW PAHs, 5 with 3-ring and 2 with 4-ring - fluoranthene and pyrene) or with 14 PAHs (from 3 to 6 rings). Natural attenuation of PAHs in all soils showed degradation capacity for the LMW PAHs, with a final content of LMW PAHs <5% of their initial concentration. Conversely, the rest of PAHs (high molecular weight PAHs, HMW) remained in the soils (61% - 83.5%), indicating abiotic dissipation of HMW PAHs due to formation of non-extractable residues in soils. The influence of the presence of HMW PAHs on the degradation of the 7 LMW PAHs was also tested, showing a general decrease in the time to obtain 50% dissipation (DT50), statistically significant for acenaphthene, acenaphthylene and fluorene. Availability enhancers showed different effects on PAHs dissipation. 2-hydroxypropyl-ß-cyclodextrin (HP) decreased DT50 of some of the lighter PAHs, whereas the rhamnolipid (RL) caused a slight DT50 increase due to its initial toxicity on native soil microorganisms, but showing later high degradation rate for LMW PAHs. On the contrary, randomly methylated-ß-cyclodextrin (RAMEB) slowed down PAHs degradation due to its high adsorption onto soil surface, blocking the desorption of PAHs from the soils. The high number of experimental factors not studied simultaneously before (soil type, co-contamination, availability enhancers and incubation time) allowed to conduct a statistical analysis which supported the conclusions reached. Principal Component Analysis separated the studied PAHs in 3 groups, in relation with their molecular weight and Kow. The first principal component was related with LMW PAHs, and separate the inefficient RAMEB from the other availability enhancers.

19.
Bioresour Technol ; 355: 127263, 2022 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-35526717

RESUMO

Petroleum refinery wastewater (PRW) is a complex mixture of hydrocarbons, sulphides, ammonia, oils, suspended and dissolved solids, and heavy metals. As these pollutants are toxic and recalcitrant, it is essential to address the above issue with efficient, economical, and eco-friendly technologies. In this review, initially, an overview of the characteristics of wastewater discharged from different petroleum refinery units is discussed. Further, various pre-treatment and post-treatment strategies for complex PRW are introduced. A segregated approach has been proposed to treat the crude desalting, sour, spent caustic, and oily wastewater of petroleum refineries. The combined systems (e.g., ozonation + moving bed biofilm reactor and photocatalysis + packed bed biofilm reactor) for the treatment of low biodegradability index wastewater (BOD5/COD < 0.2) were discussed to construct a perspective map and implement the proposed system efficiently. The economic, toxicity, and biodegradability aspects are also introduced, along with research gaps and future scope.

20.
Sci Total Environ ; 837: 155731, 2022 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-35533867

RESUMO

The present paper was aimed at investigating the role of disposable medical masks as a substrate for microbial biofilm growth and for the selection of specific microbial traits in highly impacted marine environments. In this view, we have immerged masks in a coastal area affected by a continuous input of artisanal fishery wastes and hydrocarbons pollution caused by intense maritime traffic. Masks maintained one month in the field were colonized by a bacterial community significantly different from that detected in the natural matrices from the same areas (seawater and sediments). The masks served as a viable substrate for the growth and enrichment of phototrophic microorganisms (Oxyphotobacteria), as well as Ruminococcaceae, Gracilibacteria, and Holophageae. In a follow-up investigation, masks previously colonized in the field were transferred in lab-scale microcosms which were supplemented with hydrocarbons and which contained also a piece of a virgin mask. After one month, a shift in the community composition, likely triggered by hydrocarbons addition, was observed in the previously colonized mask, with signatures characteristic of hydrocarbon-degrading microbial groups. Such hydrocarbon-degrading bacteria were also found to colonize the virgin mask. Remarkably, SEM micrographs provided indications of the occurrence of morphological modifications of the surface components of the virgin masks colonized by hydrocarbonoclastic bacteria. Overall, for the first time, we have demonstrated the potential risk for human and animal health determined by the uncorrected disposal of masks which are suitable substrates for pathogens colonization, permanence and spreading. Moreover, we have herein strengthened the knowledge on the role of hydrocarbon-degrading bacteria in the colonization and modification of fossil-based plastics in marine environment.

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