Biodegradation Activity Research Articles

Improved treatment of coking wastewater and higher biodiversity through immobilization of Comamonas sp. ZF-3 supplemented microbial community.

The aim of this study was to investigate the relationship among pollutant removal performance, microbial community structure and potential gene function of immobilized microorganisms in coking wastewater (CWW) treatment process. The results showed that the immobilized biomass containing strain Comamonas sp. ZF-3 displayed greater resistance to CWW and higher COD, NH4+-N removal efficiency (92%, 60%) than free cells (48%, 7%), meanwhile, the results from GC-MS proved main organic pollutants in CWW including phenolic compounds, heterocyclic compounds and polycyclic aromatic hydrocarbons were basically removed by immobilized microorganisms. During 123 days of degradation experiment, high-throughput 16S rRNA gene sequencing analysis of immobilized carriers showed more stable and diverse microbial community, which was consistent with simultaneous removal of COD and NH4+-N observed in carrier experiment. Among them, Comamonas sp. ZF-3 continuously remained at the highest proportion (23.25%) in immobilized carrier, while Nitrosomonas (1.47%) and Nitrospira (1.90%) were simultaneously detected. Moreover, microbial community of immobilized carriers showed higher relative abundance of potential function in membrane transport and xenobiotics biodegradation and metabolism, which may indirectly displayed biodegradation activity of immobilized functional microorganisms. This work illustrated the survival status and potential gene function of immobilized microorganisms, and provided basis for practical application of immobilized carriers in CWW treatment.

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

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

In Silico Analysis and Biochemical Characterization of Streptomyces PET Hydrolase with Bis(2-Hydroxyethyl) Terephthalate Biodegradation Activity.

Polyethylene terephthalate (PET), one of the most widely used plastics in the world, causes serious environmental problems. Recently, scientists have been focused on the enzymatic degradation of PET, an environmentally friendly method that offers an attractive approach to the degradation and recycling of PET. In this work, PET hydrolase from Streptomyces sp. W2061 was biochemically characterized, and the biodegradation of PET was performed using the PET model substrate bis (2- hydroxyethyl terephthalate) (BHET). PET hydrolase has an isoelectric point of 5.84, and a molecular mass of about 50.31 kDa. The optimum pH and temperature were 7.0 and 40°C, respectively. LC-MS analysis of the enzymatic products showed that the PET hydrolase successfully degraded a single ester bond of BHET, leading to the formation of MHET. Furthermore, in silico characterization of the PET hydrolase protein sequence and its predicted three-dimensional structure was designed and compared with the well-characterized IsPETase from Ideonella sakaiensis. The structural analysis showed that the (Gly-x1-Ser-x2-Gly) serine hydrolase motif and the catalytic triad (Ser, Asp, and His) were conserved in all sequences. In addition, we integrated molecular dynamics (MD) simulations to analyze the variation in the structural stability of the PET hydrolase in the absence and presence of BHET. These simulations showed the formation of a stable complex between the PET hydrolase and BHET. To the best of our knowledge, this is the first study on Streptomyces sp. W2061 to investigate the BHET degradation activity of PET hydrolase, which has potential application in the biodegradation of plastics in the environment.

Phenol Biodegradation by Three Bacterial Strains Stimulated by Constant Electric Field

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

Do phosphorus amendments enhance biodegradation activity in stalled petroleum hydrocarbon-contaminated soil?

Phosphorus (P) fertilizers promote soil petroleum-hydrocarbon (PHC) bioremediation by correcting carbon-to-P ratio imbalances. While these inputs create conditions favorable to microbial growth, areas of a site or an entire site with low degradation rates (i.e., "stalled") occur for unknown reasons. We hypothesized that soil conditions limit P bioavailability, leading to stalls in PHC bioremediation, and adding the correct P amendment restarts microbial activity. Soils were collected and characterized from four cold calcareous PHC-impacted sites in Saskatchewan, Canada, undergoing bioremediation. A generalized linear mixed model identified that regions with lower degradation rates possessed a neutral pH with high magnetic and salinity values. In a subsequent laboratory experiment, the proportion of benzene degraded at greater rates within active (i.e., higher degradation rates) than stalled soils, thereby following model predictions (p-value=0.19, Kruskal-Wallis). The PHC degradation efficiency of different P amendments was tested by doping stalled soils (n=3) with one of five treatments: 0 (control), 0 (autoclaved control), or 50mg phosphate kg-1 soil as sodium diphosphate, triethyl phosphate, or tripolyphosphate. Tripolyphosphate accelerated benzene degradation (75.5±5.4%) in one stalled soil (Outlook 323) and increased degradation non-significantly (43.9±9.4%) in another (Allan 917). Alternatively, the final sample (Davidson 421) possessed the greatest benzene removal with no amendments. This implies that soil P bioavailability may not be the sole cause of decreased microbial activity. Accordingly, combining model outputs with mineralogy and microbiology investigations could enhance PHC biodegradation rates in these cold calcareous soils.

Exploring long-term retention and reactivation of micropollutant biodegradation capacity

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

Defluorination of Organofluorine Compounds Using Dehalogenase Enzymes from Delftia acidovorans (D4B).

Organofluorine compounds have been widely used as pharmaceuticals, agricultural pesticides, and water-resistant coatings for decades; however, these compounds are recognized as environmental pollutants. The capability of microorganisms and enzymes to defluorinate organofluorine compounds is both rare and highly desirable to facilitate environmental remediation efforts. Recently, a strain of Delftia acidovorans (D4B) was identified with potential biodegradation activity toward perfluoroalkyl substances (PFAS) and other organofluorine compounds. Genomic analysis found haloacid and fluoroacetate dehalogenases as enzymes associated with Delftia acidovorans. Here, defluorination activity of these enzymes toward different fluorinated substrates was investigated after their recombinant expression and purification from E. coli. Using an electrochemical fluoride probe, 19F NMR, and mass spectrometry to monitor defluorination, we identified two dehalogenases, DeHa2 (a haloacid dehalogenase) and DeHa4 (a fluoroacetate dehalogenase), with activity toward mono- and difluoroacetate. Of the two dehalogenases, DeHa4 demonstrated a low pH optimum compared to DeHa2, which lost catalytic activity under acidic conditions. DeHa2 and DeHa4 are relatively small proteins, operate under aerobic conditions, and remain active for days in the presence of substrates. Significantly, while there have been many reports on dehalogenation of monofluoroacetate by dehalogenases, this study adds to the relatively small list of enzymes reported to carry out enzymatic defluorination of the more recalcitrant disubstituted carbon in an organofluorine compound. Thus, DeHa2 and DeHa4 represent organofluorine dehalogenases that may be used in the future to design and engineer robust defluorination agents for environmental remediation efforts.

Development of antioxidant film based on gelatin and carboxymethylcellulose incorporated with Tecoma stans (L.) Juss. ex Kunth Petals extract for biodegradable food packaging

The aim of this research was to develop a novel combination of antioxidant blended film for use as biodegradable packaging in the food industry. The antioxidant film was prepared based on gelatin (G) and carboxymethyl cellulose (CMC) incorporated with Tecoma stans (L.) Juss. ex Kunth petals extract (TKE) at various concentrations (0.5, 1.0, and 2.0 mg∙L‒1) via solution casting method. The structural and surface morphology of G/CMC-TKE film were characterized using FTIR spectrometry technique and scanning electron microscopy (SEM), including determining antioxidant activity, water solubility, water vapor permeability, and biodegradability. According to FTIR analysis, the significant interaction between the gelatin and CMC chain is associated with hydrogen bonding. Adding TKE into the blended films significantly increased their roughness, thickness and antioxidant activity while decreasing their water solubility and water vapor transmission. Likewise, the biodegradability of the films containing antioxidants exhibited greater degradation values than the pure G/CMC film, and all of the biofilms was entirely degraded (>80%) in 14 days. The G/CMC-TKE 2.0 demonstrated the best antioxidant (74.47%), biodegradable activity (95.85% in 14 days), and the lowest water solubility (61.80%) and water vapor transmission rate (3.2483 g∙m‒2∙day‒1), which could be a feasible candidate for the food active packaging.

Biodegradative Activities of Some Indigenous Farm Soil Bacteria on Selected Pesticides

Biodegradative Activities of Some Indigenous Farm Soil Bacteria on Selected Pesticides

Degradation of Dimethyl Phthalate and Diethyl Phthalate by Bacteria Isolated from Jazan, Saudi Arabia

P hthalate esters (PAEs) are commonly utilized in commercial, industrial, and medical applications. Various concentrations of PAEs have been detected in seawater samples and treated wastewater obtained from wastewater treatment plants in Saudi Arabia. Since these compounds pose adverse effects to human health, it is vital to develop efficient strategies to eliminate phthalate contamination from environments. In the present study, an enrichment technique was used to isolate phthalate-degrading bacteria from seawater and from activated sludge collected at Jazan Wastewater Treatment Plant, Saudi Arabia. Bacteria with the capability of degrading dimethyl phthalate (DMP) or diethyl phthalate (DEP) were isolated using minimum salt medium supplemented with these compounds as the sole carbon and energy source. High-performance liquid chromatography (HPLC) was utilized to evaluate the residual concentration of DMP and DEP. Using the 16S rRNA gene sequencing technique, the isolates with maximum DMP biodegradation activity were identified as Achromobacter sp. M1 and Pseudomonas sp. M2, while the isolates with maximum DEP biodegradation activity were identified as Pseudomonas sp. E2 and Pseudomonas sp. E3. The optimum bacterial growth was achieved at 30°C, pH 7.0, and 2% NaCl, except for Pseudomonas sp. E3, which demonstrated its maximum growth in the absence of NaCl. The highest biodegradation rate for all the bacterial strains (> 99.0%) was achieved at 30°C, pH 7.0, and up to 2% NaCl within 4 days. Concurrently, Pseudomonas sp. M2 and Pseudomonas sp. E2 exhibited remarkable degradation rates (97.5% and 56.7%, respectively) at 4% NaCl whereas Pseudomonas sp. E3 showed its highest DEP degradation (82.4%) after 4 days in the absence of NaCl. This study offers potential candidates, including Achromobacter sp. M1, Pseudomonas sp. M2, Pseudomonas sp. E2, and Pseudomonas sp. E3, for the proficient biodegradation of DMP and DEP.

Microbiological treatment of post-industrial water: Example of efficient bioremediation of the heavily polluted Kalina pond, Poland

The Kalina pond has been well known as a severely degraded area in the Silesia region, Poland. The environmental deterioration results from high contamination of water and bottom sediments with recalcitrant and toxic organic compounds, mainly phenol. The study was aimed at developing a bioremediation-based approach suitable for this type of polluted areas, involving microbiological treatment of water as a key and integral part of other necessary actions: mechanical interventions and the use of physical methods. During the initial biological treatment stage, autochthonous microorganisms were isolated from contaminated samples of water, soil and sediment, then subjected to strong selective pressure by incubation with the pollutants, and finally, cultivated to form a specialised microbial consortium consisting of five extremophilic bacterial strains. Consortium propagation and its biodegradation activity were optimised under variant conditions enabling bacteria to proliferate and to obtain high biomass density at large volumes allowing for the in situ application. After installing aeration systems in the pond, the consortium was surface-sprinkled to launch bioremediation and then both bacterial frequency and the contaminant level was systematically monitored. The complex remediation strategy proved efficient and was implemented on an industrial scale enabling successful remedial of the affected site. Treatment with the specifically targeted and adapted microbial consortium allowed for removal of most organic pollutants within a four-month season of 2022: the chemical oxygen demand (COD) value decreased by 72%, polyaromatic hydrocarbon (PAH) level by 97%, while the content of total phenols and other monoaromatic hydrocarbons (BTEX) dropped below the detection thresholds.

Fungal Diversity in Nam River and Their Biodegradative Activities

145 fungal isolates were obtained from three sampling sites situated within the Nam River basin, located in the southern region of South Korea. Through ITS sequence analysis, the fungal isolates were identified to comprise 55 species of ascomycetes and 11 species of basidiomycetes. The 55 species of ascomycetes exclusively belong to the phylum Pezizomycotina, comprising 33 species of Dothideomycetes, 6 species of Eurotiomycetes, and 16 species of Sordariomycetes. Regarding their plant pathogenicity, an investigation into the fungi’s ability to penetrate solid media revealed Nigrospora chinensis as displaying the highest growth, followed by Pseudopestalotiopsis theae, various Curvularia species, Diaporthe species, and Alternaria alternata. Further research associating this penetration ability with fungal pathogenicity is deemed necessary. Among the 10 fungal species exhibiting penetration abilities, an examination of their capability to degrade biological polymers revealed that two strains of D. phaseolorum displayed exceptional polymer degradation. These strains exhibited remarkable abilities in decomposing malachite green and crystal violet, both recalcitrant dyes. This study underscores the potential utilization of fungal diversity in freshwater environments as a foundational approach to address freshwater pollution issues.

Application of MicroResp™ for quick and easy detection of plastic degradation by marine bacterial isolates

Microplastic debris in the marine environment is a global problem. Biodegradable polymers are being developed as alternatives to petroleum-based plastics, and quick and easy methods for screening for bacterial strains that can degrade such polymers are needed. As a screening method, the clear zone method has been widely used but has technical difficulties such as plate preparation and interpretation of results. In this study, we adapted the MicroResp™ system to easily detect biodegradation activity of marine bacteria in a 3-day assay. Among the 6 bacterial strains tested, 3, 2 and 1 strain degraded poly (butylene succinate-co-adipate) (PBSA), poly (ε-caprolactone) (PCL) and poly (3-hydroxybutyrate-co-3-hydroxyhexanoate), respectively. Only one strain that showed degradation activity of PBSA and PCL in the MicroResp™ system was also positive in the clear zone assay on the respective emulsion plates. Our results show that the adapted MicroResp™ system can screen for bacterial strains that degrade plastic.

Microbial degradation of pyridine: a proposed nitrogen metabolism pathway deciphered in marine mangrove Bacillus aryabhattai strain NM1-A2

BackgroundDiverse microbes, such as bacteria, are of immense worth to mangrove ecosystems due to their adaptability to salinity and variable environmental characteristics conditions. Pyridine and its derivatives compose most heterocyclic aromatic compounds largely produced by human activities that lead to environmental pollution. Bacteria have a crucial role in the nutrient cycling of carbon and nitrogen etc., to understand their functional involvement with environmental factors or ecosystem functioning as well as the species invasion and domestic or agriculture pyridine degradation pollution activities that threaten the mangrove ecosystem.MethodsThis work established the genetic-based molecular degradation of organic compounds in the mangrove ecosystem, which ultimately makes the availability of nutrients. As well as the effects of various abiotic factors on pyridine degradation to discover the pyridine degradation and the removal of ammonia nitrogen and the proposed nitrogen metabolism pathway.ResultsThe novel bacterial strain NM1-A2 was isolated from mangrove sediments and, after 16S rRNA gene sequence analysis identified as Bacillus aryabhattai. NM1-A2 completely degraded pyridine within a 100 h incubation period at a temperature of 35 °C, an initial pH of 7.0, glucose and a pyridine concentration of 500 mg/L. The pseudo-first-order kinetics model described the pyridine biodegradation profile of NM1-A2 well. Interestingly, within 96 h the strain achieved almost complete pyridine degradation with a total organic carbon (TOC) removal of 87.9% ± 0.19% (from 377.52 ± 6.9 mg/L to 45.65 ± 0.14 mg/L). Within 96 h, the pyridine ring in the total nitrogen (TN) fraction at the maximum concentration of 55.31 ± 0.17 mg/L, furtherly 51.3% ± 2.39% of (TN) converted into Ammonia nitrogen (NH4+-N). Furthermore, NM1-A2 exhibited its pyridine biodegradation activity decreased by only 4% after three consecutive cycles (48 h each). Moreover, NM1-A2 possessed nrt-ABCD nitrate transport family and gltABCD operons that participate in the activities of glutamine and glutamate synthetase in NH4+ conversion in the nitrogen cycle. Furthermore, the nitrogen metabolism genes (nrtA, nrtB, nrtC, nirB, nirD, gltB, gltD, glnA) exhibited expression in NM1-A2.ConclusionThis research offers a potential treatment strategy for pyridine degradation in the mangrove ecosystem.Graphical

Microbial colonization patterns and biodegradation of petrochemical and biodegradable plastics in lake waters: insights from a field experiment.

Once dispersed in water, plastic materials become promptly colonized by biofilm-forming microorganisms, commonly known as plastisphere. By combining DNA sequencing and Confocal Laser Scanning Microscopy (CLSM), we investigated the plastisphere colonization patterns following exposure to natural lake waters (up to 77 days) of either petrochemical or biodegradable plastic materials (low density polyethylene - LDPE, polyethylene terephthalate - PET, polylactic acid - PLA, and the starch-based MaterBi® - Mb) in comparison to planktonic community composition. Chemical composition, water wettability, and morphology of plastic surfaces were evaluated, through Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM), and static contact angle analysis, to assess the possible effects of microbial colonization and biodegradation activity. The phylogenetic composition of plastisphere and planktonic communities was notably different. Pioneering microbial colonisers, likely selected from lake waters, were found associated with all plastic materials, along with a core of more than 30 abundant bacterial families associated with all polymers. The different plastic materials, either derived from petrochemical hydrocarbons (i.e., LDPE and PET) or biodegradable (PLA and Mb), were used by opportunistic aquatic microorganisms as adhesion surfaces rather than carbon sources. The Mb-associated microorganisms (i.e. mostly members of the family Burkholderiaceae) were likely able to degrade the starch residues on the polymer surfaces, although the Mb matrix maintained its original chemical structure and morphology. Overall, our findings provide insights into the complex interactions between aquatic microorganisms and plastic materials found in lake waters, highlighting the importance of understanding the plastisphere dynamics to better manage the fate of plastic debris in the environment.

Phenotypic and metabolic adaptations of Rhodococcus cerastii strain IEGM 1243 to separate and combined effects of diclofenac and ibuprofen.

The increasing use of non-steroidal anti-inflammatory drugs (NSAIDs) has raised concerns regarding their environmental impact. To address this, understanding the effects of NSAIDs on bacteria is crucial for bioremediation efforts in pharmaceutical-contaminated environments. The primary challenge in breaking down persistent compounds lies not in the biochemical pathways but in capacity of bacteria to surmount stressors. In this study, we examined the biodegradative activity, morphological and physiological changes, and ultrastructural adaptations of Rhodococcus cerastii strain IEGM 1243 when exposed to ibuprofen, diclofenac, and their mixture. Our findings revealed that R. cerastii IEGM 1243 exhibited moderate biodegradative activity towards the tested NSAIDs. Cellular respiration assay showed higher metabolic activity in the presence of NSAIDs, indicating their influence on bacterial metabolism. Furthermore, catalase activity in R. cerastii IEGM 1243 exposed to NSAIDs showed an initial decrease followed by fluctuations, with the most significant changes observed in the presence of DCF and the NSAID mixture, likely influenced by bacterial growth phases, active NSAID degradation, and the formation of multicellular aggregates, suggesting potential intercellular synergy and task distribution within the bacterial community. Morphometric analysis demonstrated alterations in size, shape, and surface roughness of cells exposed to NSAIDs, with a decrease in surface area and volume, and an increase in surface area-to-volume ratio (SA/V). Moreover, for the first time, transmission electron microscopy confirmed the presence of lipid inclusions, polyphosphates, and intracellular membrane-like structures in the ibuprofen-treated cells. These results provide valuable insights into the adaptive responses of R. cerastii IEGM 1243 to NSAIDs, shedding light on the possible interaction between bacteria and pharmaceutical compounds in the environment.

Enhancement effect of AgO nanoparticles on fermentative cellulase activity from thermophilic Bacillus subtilis Ag-PQ

BackgroundCellulase is an important bioprocessing enzyme used in various industries. This study was conducted with the aim of improving the biodegradation activity of cellulase obtained from the Bacillus subtilis AG-PQ strain. For this purpose, AgO and FeO NPs were fabricated using AgNO3 and FeSO4·7H2O salt respectively through a hydro-thermal method based on five major steps; selection of research-grade materials, optimization of temperature, pH, centrifuge, sample washed with distilled water, dry completely in the oven at the optimized temperature and finally ground for characterization. The synthesized NPs were characterized by scanning electron microscope (SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD) to confirm the morphology, elemental composition, and structure of the sample respectively. The diameter of the NPs was recorded through SEM which lay in the range of 70–95 nm. ResultsCultural parameters were optimized to achieve better cellulase production, where incubation time of 56 h, inoculum size of 5%, 1% coconut cake, 0.43% ammonium nitrate, pH 8, and 37 °C temperature were found optimal. The enhancing effect of AgO NPs was observed on cellulase activity (57.804 U/ml/min) at 50 ppm concentration while FeO NPs exhibited an inhibitory effect on cellulase activity at all concentrations. Molecular docking analysis was also performed to understand the underlying mechanism of improved enzymatic activity by nanocatalysts. ConclusionThis study authenticates AgO NPs as better nanocatalysts for improved thermostable cellulase biodegradation activity with the extraordinary capability to be potentially utilized in bioethanol production. Graphical Abstract▪

Development of Active Antibacterial CEO/CS@PLA Nonwovens and the Application on Food Preservation.

The biodegradable activity antibacterial materials have been widely applied on food preservation because they not only protect foods from pathogenic attacks but also relieve environmental pollution. Biodegradable melt-blown nonwovens (MB) have several advantages over the other materials in terms of a simpler and more environmentally friendly fabrication process, higher specific surface area, and lower cost. Herein, polylactic acid (PLA) MB is first modified by polydopamine (PDA) to activate the surface. Then, chitosan (CS) and cinnamon essential oil (CEO) are used to decorate the surface of the modified PLA MB via a simple one-pot method to prepare CEO/CS@PLA MB with different CEO contents. Compared with PLA MB, CEO/CS@PLA MB had a rougher surface and larger average fiber diameter, while the average pore diameter and air permeability reduced. The input of CEO led to a decrease in the tensile strength of CEO/CS@PLA MB and an obvious increase in the elongation at break. The combination of CS and CEO shows excellent synergistic antibacterial effect. The antibacterial efficiencies of CEO/CS@PLA MB against Escherichia coli and Staphylococcus aureus enhance with the increase of the CEO content. When the weight ratio of CS to CEO is 1:2, the antibacterial efficiencies of CEO2/CS@PLA MB against E. coli and S. aureus are 99.98 and 99.99%, respectively. When being applied to the preservation of fresh strawberry, CEO2/CS@PLA MB can effectively inhibit the microbial growth in strawberry and reduce decay, which extends the shelf time of strawberry.

Preparation and characterization of egg white protein film incorporated with epigallocatechin gallate and its application on pork preservation.

The aim of this study was to develop the composite films with antioxidant and biodegradable activity based on egg white protein (EWP) and epigallocatechin gallate (EGCG). Water susceptibility, light transmittance, microstructure and antioxidant properties of the composite films without and with EGCG were fully characterized. It was noted that the addition of EGCG might decrease the moisture content, water solubility and swelling capacity. SEM micrographs revealed that discontinuous blocks and rough surfaces were caused by increasing concentration of EGCG, whereas compact and homogeneous particles appeared when the concentration of EGCG reached to 80μmol/L. Moreover, the biodegradability of the composite films was demonstrated by the soil degradation properties that they can be almost completely degraded within ten days. Experimental results on the application in chilled fresh pork showed that the EWP-based films could play an antioxidant role when incorporated with EGCG, indicating their great potential for food packaging.

Microbial degradation of the benzimidazole fungicide carbendazim by Bacillus velezensis HY-3479.

Carbendazim (methyl benzimidazol-2-ylcarbamate: MBC) is a fungicide of the benzimidazole group that is widely used in the cultivation of pepper, ginseng, and many other crops. To remove the remnant carbendazim, many rhizobacteria are used as biodegradation agents. A bacterial strain of soil-isolated Bacillus velezensis HY-3479 was found to be capable of degrading MBC in M9 minimal medium supplemented with 250mg/L carbendazim. The strain had a significantly higher degradation efficiency compared to the control strain Bacillus subtilis KACC 15590 in high-performance liquid chromatography (HPLC) analysis, and HY-3479 had the best degradation efficiency of 76.99% at 48h. In gene expression analysis, upregulation of carbendazim-degrading genes (mheI, hdx) was observed in the strain. HY-3479 was able to use MBC as the sole source of carbon and nitrogen, but the addition of 12.5mM NH4NO3 significantly increased the degradation efficiency. HPLC analysis showed that the degradation efficiency increased to 87.19% when NH4NO3 was added. Relative gene expression of mheI and hdx also increased for samples with NH4NO3 supplementation. The enzyme activity of the carbendazim-degrading enzyme and the 2-aminobenzimidazole-degrading enzyme was found to be highly present in the HY-3479 strain. It is the first reported B. velezensis strain to biodegrade carbendazim (MBC). The biodegradation activity of strain HY-3479 may be developed as a useful means for bioremediation and used as a potential microbial agent in sustainable agriculture.