International Biodeterioration & Biodegradation最新文献

Environmental contamination by nitrogen compounds such as ammonium and nitrate has increased extensively in the recent past, which necessitates the development of eco-friendly remediation technologies. In this study, three matrix types including pumice, aquarium ceramic filter, and calcium alginate beads were used to facilitate nitrogen removal with an immobilized heterotrophic nitrifying-aerobic denitrifying (HNAD) bacterial consortium. The HNAD bacterial consortium was made of Pseudomonas monteilii Nht, Pseudomonas mendocina AquaN, Rhodococcus erythropolis R1, and Acinetobacter calcoaceticus SCC2. The quality parameters for immobilization, such as the number of immobilized cells and their viability, were assessed. The highest number of bacterial cells (3.4 × 10 ⁹) was immobilized on the aquarium ceramic filter, with 53% cell viability at 30°Ⅽ for two months. Pumice, aquarium ceramic filter, and calcium alginate achieved NH₄⁺-N removal efficiencies of 85.3 ± 1.7%, 87.3 ± 2.2%, and 77.5 ± 3.99% within 24 h, respectively, and removed NO₃⁻-N by 88.23 ± 0.36%, 93.95 ± 0.00%, and 71.29 ± 6.49% over 60 h. Additionally, immobilized cells on pumice and ceramic filter retained up to 84% of NH₄⁺-N removal efficiency after 14 reuse cycles. These findings indicate that the immobilized HNAD bacterial consortium on the aquarium ceramic filter can be used as a suitable biofilter for treatment of high nitrogen wastewater.

Conventional polymers are environmentally damaging materials; therefore, global efforts are being made to gradually replace these conventional polymers with bio-based, biodegradable, and compostable plastics due to claims of being more sustainable than petroleum-based plastics. However, such claims may not be based on reality, and unregulated bio plastics may cause environmental anarchy similar to conventional plastics. The degradation of bioplastics has received significant attention because it is the parameter used to evaluate their end-of-life disposal and to assess their environmental shortcomings - where the bioplastics which degrade completely in different environments, thus, considered as an environmental-friendly polymers. Upon disposal, the bioplastics decompose in a bio-active medium by microorganisms such as algae, bacteria, and fungi or to humus, water, and CO₂ by marine water. Different standardization and certification bodies have set the standards for bioplastics, compostable, and biodegradable plastics to evaluate the environmental constraints of bioplastics. These standards support various industries in creating bioplastics. Thus, it is important to harness the regulatory power to bring all the standardization and certification bodies (both at the national and international levels) together in setting standards with a high threshold to classify bio-based plastics, biodegradable plastics, and compostable plastics.

Similar to the deterioration of construction materials by airborne algae, hydrophytic algae can deteriorate cementitious materials and change the performance of structures, thereby reducing the safety and economics of marine facilities. Frequent outbreaks of green tides have occurred in recent years, and algae have been shown to deteriorate calcium substances in cementitious materials. Therefore, the pattern of deterioration of cement by algae as a result of green tide outbreaks is important for extending the durability of marine installations. For this reason, the dominant species of the green tide outbreak, Enteromorpha, and the marine primary producer, diatoms, were selected to simulate the green tide outbreak in this paper. Then, in the paper, the colonization law of Enteromorpha and diatom and the calcium loss law in mortar are discussed. Results showed four stages of Enteromorpha-diatoms colonization on the mortar surface (diatoms colonization within 15 days, release of spores from Enteromorpha, germination of spores from Enteromorpha within 60 days, and transformation of the relationship between the colonization of Enteromorpha and diatoms). Three channels for the loss of calcium on the surface of the mortar include the uptake and transformation, the complexation of biofilm, and the dissolution and deposition. Additionally, Enteromorpha-diatoms can deteriorate the mortar surface, mineral composition, and microstructure.

The Lactobacillus consortium LBC-4 was evaluated for its ability to mitigate zearalenone (ZEN) contamination, addressing a critical food and health security issue. This study highlights the potential of LBC-4 in mycotoxin detoxification through comprehensive morphological and genotypic analyses. The LBC-4 consortium, confirmed by PCR to encompass various Lactobacillus strains, efficiently adsorbed 88.7% and 89% of ZEN within 1 and 24 h at 37 °C, respectively, demonstrating a dynamic relationship between bacterial growth and mycotoxin sequestration. Optimal ZEN removal was achieved at 37 °C and pH 7.0 to 8.0. The mechanisms of ZEN removal were elucidated, revealing the roles of cell wall, viable cells, and culture supernatants. Heat-treated LBC-4 showed enhanced ZEN adsorption, supported by Scanning Electron Microscopy and Fourier Transform Infrared Analysis, which indicated significant structural changes. Additionally, LBC-4 degraded ZEN into less toxic derivatives, including 6, 8, 10-trihydroxy zearalenol-14-sulfate, 6, 8, 10-trihydroxy zearalenol, 6, 8-dihydroxy zearalenol, and 6, 8, 10-trihydroxy zearalenol, underscoring the consortium's multifaceted mechanisms and its potential for effective microbial ZEN removal.

Many studies have used microbial fuel cell (MFC) to enhance biological reactions to improve the removal of pollutants, but the mechanisms of enhancement are unclear. The fundamental difference between biological reactions in MFC and traditional biological reactions lies in the presence of the electric field. This review analyzes the current research status of the mechanism of electron transfer by electro-active bacteria (EABs) in MFC system and the modulation effect of electric field on microorganisms, and summarizes the research progress on the enhancement mechanisms of nitrogen removal by MFC with a focus on biocathode denitrification. In addition, constructive suggestions on how to further clarifying the enhancement mechanism of MFC on biological responses have been also put forward. This review provides the theoretical basis for further investigation of the mechanisms of enhancement of other biological reactions by MFC.

The degradation of stone heritage buildings by pioneer plants such as algae is a major challenge in heritage conservation research worldwide. At present, there is a lack of effective algaecides to inhibit the growth of algae on stone structures, prompting an urgent need to explore effective green methods to remove algae colonizing on surfaces of stone heritage buildings. Therefore, we explored the use of aqueous and alcoholic extracts of four plant leaves (Cinnamomum cassia leaf, Syzygium aromaticum leaf, Thymus mongolicus leaf and Pogostemon cablin leaf) to prepare silver nanoparticles. By optimizing the synthetic parameters, we optimized the yield of the nanoparticles and examined their algicidal activities through in-vitro and in-situ experiments. The experimental results showed that the chlorophyll-a concentrations of algae treated with nano-silver synthesized from the alcoholic extract of Cinnamomum cassia leaf decreased approximately threefold, and the algae removal rate reached 71.34%. Meanwhile, nano-silver treatment made the color of the stone chips colonized with algae close to the color of the uncolonized algae, which demonstrated that the nano-silver can effectively remove the algae colonized on the stone chips. This study confirms that nano-silver synthesized from plant leaves offer a viable strategy as a ‘green’ algaecide for stone heritage buildings.

Microbial remediation presents a promising and sustainable approach for combating environmental pollutants. The genus Exiguobacterium thrives in diverse habitats, including extreme environments, and effectively mitigates a wide array of pollutants through its versatile detoxification mechanisms. Notably, these bacteria are adept at removing heavy metals such as chromium, arsenic, cadmium, mercury, lead, nickel, and vanadium from both soil and water, thereby reducing their toxicity and bioavailability. Additionally, Exiguobacterium demonstrates significant capabilities in biodegrading various organic pollutants, including synthetic dyes, nitroaromatic compounds, petroleum hydrocarbons, and plastic polymers. Despite its ecological and environmental importance, article dedicated to this genus remains relatively sparse. This review aims to comprehensively summarize the application and mechanism of genus Exiguobacterium in remediating toxic heavy metals and organic pollutants. It begins with a brief description of the genus's taxonomic characteristics and ecological diversity, followed by a detailed examination of its detoxification and biodegradation mechanisms in response to pollutant stress. Furthermore, it proposes avenues for future research, including the discovery of novel functional strains, elucidation of detoxification and degradation pathways, and development of genetic editing tools to enhance practical applications in environmental remediation.

To reduce greenhouse gas emissions during the composting of animal manure and promote the resource utilization of Chinese herbal plants, experiments on pig manure composting were conducted in a plastic greenhouse. A mixture of herbal powders (Radix isatidis and Radix Polygoni Multiflori, mixed in a 1:1 ratio) was added to the pig manure at concentrations of 0.05%, 0.1%, and 0.5% (w/w), respectively. The results showed that the emission peaks of greenhouse gases occurred in the early stages of composting. The addition of 0.5% of a mixture of Chinese herbal plant powders resulted in a significant reduction in cumulative emissions of CO₂ (45.0%) and N₂O (60.0%) compared to the control. This treatment also resulted in the lowest global warming potential, measured at 91.3 g kg⁻¹, and significantly increased the germination index. The study concluded that adding 0.5% Chinese herbal plant powder to compost effectively mitigated greenhouse gas emissions during the composting process.

Several explanations have been proposed for the rapid spread of Solidago canadensis in various environments. Yet, the specific role of soil prokaryotes in this process remains unclear. To understand the prokaryotic role, we conducted a field study in eastern China, where S. canadensis invaded the native plant Humulus scandens. Prokaryotic communities in the soil were studied across three levels of invasion intensity: low, medium, and high (S. canadensis less than 10, about 50, and above 90%, respectively). We found that the S. canadensis invasion decreased the total prokaryotic abundance in the bulk soil (1.61 ± 0.57 × 10⁸ to 5.78 ± 3.65 × 10⁷ copies g⁻¹ DW), but increased the total prokaryotic abundance in S. canadensis (7.72 ± 5.11 × 10⁷ to 1.27 ± 0.71 × 10⁸ copies g⁻¹ DW) and H. scandens rhizosphere (1.11 ± 0.28 × 10⁸ to 1.79 ± 0.68 × 10⁸ copies g⁻¹ DW). S. canadensis invasion enhanced nutrient-releasing microorganisms (Actinobacteria) (p < 0.05) and disease-resistant microorganisms (Nocardioides) (p < 0.05), while decreasing N-cycling microorganisms (Thaumarchaeota and Nitrospirae) (p < 0.05). This study suggests that S. canadensis may enhance its invasion by modulating the species and relative abundance of functional microorganisms in the bulk soil.

The copious compatible solute dimethylsulfoniopropionate (DMSP) plays significant roles in marine ecosystems. The DMSP degradation pathways in strain Alcaligenes faecalis M3A have been comprehensively studied, in which DMSP was cleaved into dimethyl sulphide (DMS) and acrylate. However, the transcriptional regulatory mechanism of DMSP degradation is not fully elucidated. In this study, the TetR/AcrR family transcriptional regulator DdaR repressing acuI operon in strain M3A was investigated. The transcription start sites and promoters of the acuI and ddaR operons was identified. DdaR bound to both the acuI and ddaR promoter regions in EMSA experiment. Two binding sites of DdaR shared conserved motif 5′-CNNCGTNACGNNG-3′ which was essential for the DdaR binding. DdaR was inhibited from binding to the acuI promoter region by acrylate, which acted as a ligand of DdaR. Site-directed mutagenesis was used to investigate the impact of four key amino acid residues (Y61, K67, E135, and I169) in DdaR, revealing their essential roles in the functioning of DdaR. The findings of this study unveil a negative transcriptional regulation mechanism of DMSP degradation in A. faecalis M3A by DdaR and provide a new understanding of the TetR/AcrR-type transcriptional regulators.