International Biodeterioration & Biodegradation最新文献

Heavy metal pollution poses an immense challenge to humanity owing to its severe toxic effects on living beings. This study investigates the bioremediation potential of the urease-hydrolyzing and halophilic bacterium Bacillus paramycoides- MSR1 to reduce the toxicity of cadmium (Cd) in the environment under salt stress through microbially induced calcium carbonate precipitation (MICCP). The enzymatic activity of urease and calcium carbonate (CaCO₃) precipitation was studied under different concentrations of salt stress (0%, 3.5%, 5%, 7.5%, 10%, 15%) and maximum urease activity of 735.7 U/ml was recorded at 5% salt stress. The urease activity and CaCO₃ precipitation decreased with increasing Cd toxicity (0, 10, 20, 30, 40, 50, and 60 μM). The maximum concentration of Cd endured by bacteria was determined by IC₅₀ value and the minimum inhibitory concentration of Cd was recorded as 9.86 μM under 5% stress. Atomic absorption spectroscopy results revealed that Cd removal was as high as 90.3% under 5% salt stress. Microstructural analysis through FE-SEM revealed the surface topography of carbonate crystals as rhombohedral, whereas EDS confirmed the presence of CaCO₃ and Cd in the bio-precipitates. These results suggest that MICCP is a potential, environmentally safe, low-cost technique and an excellent alternative to conventional heavy metal removal strategies from the environment.

In order to obtain marine-derived enzymes suitable for protein hydrolysis in acid brewing system, seven species of fungi were obtained from mangrove soil. One of the strains, Aspergillus tubingensis, was determined to have a high acid protease production capacity. Its fermentation broth was purified and the obtained protease was identified as aspergillopepsin I (ATAP) with a molecular weight of 41205 Da. Homology modelling shows that ATAP contains three active sites, each containing to a Zn atom and amino acid residues. The enzyme had the highest relative activity at pH 3.5 and 35–40 °C, and exhibited pH and thermal stability at pH 3.0–3.5 and 20–50 °C. ATAP showed certain salt tolerance. K⁺ and Zn²⁺ promoted the enzyme activity, while Mg²⁺, Cu²⁺, Co²⁺, and Fe²⁺ slightly inhibited the enzyme activity. The results of inhibitors suggest that ATAP belongs to the class of aspartic proteases containing metal atoms. Furthermore, the results of enzymatic hydrolysis of defatted soybean powder showed that the contents of soluble protein, amino nitrogen, free amino acids and the proportion of small molecular peptides (<3 kDa) in the hydrolysate increased significantly. In addition, molecular docking of ATAP and aspergillopepsin I from Aspergillus oryzae 3.042 with soybean globulins (7S and 11S), respectively, showed better hydrolysis of soybean globulins by the former, especially for 7S globulin. Visual analysis indicated the interaction forces between enzymes and soybean globulins were dominated by hydrogen bond and hydrophobic interaction. In conclusion, ATAP may be a candidate as an enzyme preparation for the hydrolysis of soybean proteins.

This article explores the feasibility of rare earth element-tannin complexes as a wood preservative. The tannins (T) from Cercis glabra Pampan. are extracted, sulfonated (ST), and coordinated with lanthanum (La) elements to fabricate the complexes (La-T, and La-ST). Results show that two stable complexes, La-T and La-ST, are successfully formed by coordinating the La-ions with the phenolic hydroxyl groups in T and ST. Sulfonated tannins have a better adsorption capacity for lanthanum ions. The mass percentage of La in La-ST (36.50%) is higher than that in La-T (24.85%). The results of the white-rot decay test reveal that wood treated with La-T (1.98%) and La-ST (2.58%) preservatives has significantly lower weight loss rates compared to the untreated (28.94%). However, the brown rot decay test demonstrates that wood treated with La-T (62.68%) and La-ST (50.81%) only has slightly lower weight loss rates compared to the untreated (71.84%). Finally, the leaching of La-T and La-ST treated poplar wood was significantly lower than La self-treated ones. This novel approach can produce stable rare earth-wood preservatives and improve the wood's bio-durability and anti-leaching properties, thus remarkably enhancing the outdoor performance of modified wood products.

The study explores the resilience of fungi and bacteria in degrading three selected cosmetic ingredients, butylated hydroxy anisole (BHA), benzophenone 3 (BZ3), and decamethylcyclopentasiloxane (D4), across different pH levels and temperatures. Understanding microbial adaptability and optimizing degradation conditions are crucial for effective biodegradation processes, given the influence of pH and temperature on microbial activity. Trametes versicolor and Pseudomonas aeruginosa were chosen as representative fungal and bacterial species for degradation studies, with synthetic wastewater utilized alongside traditional growth media. Our research pioneers the utilization of synthetic wastewater alongside traditional growth media, recognizing its untapped potential in enhancing degradation efficiency. By subjecting fungi to environmental stressors, we illuminate the adaptive strategies employed by these organisms, crucial for optimizing biodegradation processes. The hypothesis posited that synthetic wastewater would enhance degradation efficiency, while subjecting fungi to environmental stressors would elucidate their adaptability. Two temperatures (25 °C & 37 °C) and two pH levels (2.5 & 6.89) were examined to mimic real-world conditions, employing advanced techniques like Nuclear Magnetic Resonance (NMR) to assess degradation efficiency. Results revealed successful fungal degradation, particularly with complete D4 degradation in synthetic wastewater and partial degradation in PDB media at 25 °C. At 37 °C, complete BHA and BZ3 degradation occurred in PDB media, with higher rates in synthetic wastewater. However, bacterial degradation was incomplete, especially in synthetic wastewater. Leveraging synthetic wastewater as a medium for targeted degradation of multiple pollutants by specific microbial species represents an innovative advancement in biodegradation methodologies, highlighting the importance of microbial adaptability in biodegradation processes.

Oligotrophic conditions have important role in the evolution of life and also the study of ecological status and ecological functions of oligotrophic bacteria in such ecosystems. In this study, the oligotrophic characteristics of the experimental strain Rhodoligotrophos defluvii lm1^T (hereinafter referred to as lm1^T) isolated from activated sludge were investigated. The results indicated that lm1^T was able to grow normally in Luria-Bertani (LB) and diluted LB solid agar plates, demonstrating it to be a facultative oligotrophic bacterium. Research about carbon source and genome analysis revealed that lm1^T lacks 6-phosphofructokinase in the glycolysis process, resulting in the inability to convert glucose-6-phosphate to fructose-6-phosphate, which prevented lm1^T from utilizing glucose. And in line with that, lm1^T can utilize 1,6-diphosphofructose, acetate, propionate, and butyrate to meet its growth requirements. lm1^T possesses a wide range of nitrogen sources utilization, including NaNO₃, urea, NH₄Cl, (NH₄)₂SO₄, peptone, and yeast extract, enabling its adaptation to various complex environments. Additionally, comparative genomic analysis of lm1^T and the model strain Rhodoligotrophos appendicifer 120-1^T revealed that lm1^T had more genes related to degradation metabolism, which aided its adaptation to complex environments.

Essential oils (EO) are still a viable research topic, especially in light of the sustainable development concept and utilization of natural resources. The apparent weakness on the research of this topic is shown in the scientific contents with less or no substantiation of the active chemical constituents and then the mechanisms of the effectiveness to advance the chemistry and technology application. On this aspect, it is very similar to the situation faced by the Chinese traditional medicine of herbs. Because of this, the pure science of this subject on EO must be focused on to further advance this subject for a strong science-based subject. A strong chemistry-based approach is needed in all research before the useful activity and application of any essential oil can be proposed.

Sustainability-driven innovations with non-toxic coating developing is essential. Here, we utilized the waste mussel shells as an alternative antifouling coating to test the potential impacts on biofilm formation and then Mytilus coruscus settlement. Compared with Natural Mussel Shell Powder (NMSP), the bacterial density of biofilm on 10 mg/mL Calcined Mussel Shell Powder (CMSP) coating was 63.09%, lowered significantly (p < 0.05). Further analysis of X-ray diffraction test showed the phase transformation appeared in the CMSP in comparison to NMSP. The biofilm bioassays showed that in 28-day-old natural biofilm, compared with Glass and PDMS, the bacterial density in 10 mg/mL CMSP decreased by 46.58 % and 34.60 %, respectively, and the diatom density decreased by 71.07 % and 42.99 %, respectively. Compared to Glass and PDMS, the relative abundance of Psychrobacter and Loktanella in the 28-day-old biofilms on CMSP coating was reduced, but that of Erythrobacter increased. Simultaneously, settlement on 10 mg/mL CMSP was reduced by 65.31 % and 72.13 %, respectively, compared to PDMS and Glass in the case of 28-day-old biofilms. These results demonstrate the viability of CMSP as a coating and provide a sustainable solution to against marine biofouling.

The integrated bioremediation systems (IBSs) are becoming increasingly widespread to treat aquaculture wastewater. However, there is still significant room for the improvement of technological processes of the IBS. In this study, exogenous compound bacteria (ECB) were added to the system and combined with ceramsite to treat wastewater. The changes in bacterial communities within the system were analyzed through high-throughput sequencing and multivariable statistics, and the dynamic changes in bacterial communities within the system was visualized. The results showed that ECB significantly increased the diversity and affected the assembly of the bacterial communities in the water and biofilm, forming three succession stages. The ECB promoted the increase of denitrifying bacteria which play a key role in the ecological function of the system. Sedimentitalea and Paracoccus were the biomarkers of the water and biofilms in the treatment group, and were significantly positively correlated with the denitrification process. The overall nutrients removal efficiency of the treatment group exceeded 80%. And the removal efficiency of TN, NH₄⁺-N, NO₃⁻-N, NO₂⁻-N, and PO₄^3--P in the treatment group were significantly higher than those in the control group, which indicated the ECB led to a significant improvement in purification effectiveness. The significant influence of the ECB on the IBS provided a preliminary theoretical basis for improving the system process, enhancing nutrient removal performance, and exploring system working mechanisms.

It is well known that anthracene can cause serious health problems, which is why anthracene biodegradation as a method to reduce health risks has drawn the interest of researchers. However, antibiotic contamination in the environment can seriously affect the biodegradation of anthracene. In the present study, Comamonas testosteroni (CT1) had the highest degradation efficiency of anthracene (88.1%), and was still 46.6% when erythromycin concentration was 1/4MIC (8 μg mL⁻¹). Also, compared to CK, the prokaryotic transcriptome analysis of CT1 in anthracene degradation revealed an up-regulated gene that encodes antibiotic biosynthesis monooxygenase (ABM) in both anthracene and anthracene-erythromycin groups. In addition, compared to strain CT1, the CtABM knockout mutant (CT-M) showed a significant decrease in anthracene degradation efficiency. In contrast, Escherichia coli (E.coli) DH5α transformed with CtABM (EM1) exhibited a faster degradation efficiency than DH5α. Furthermore, the antimicrobial susceptibility test showed that compared to DH5α, EM1 had significant resistance to erythromycin. And the purified recombinant CtABM (rABM) had a specific activity of 2.53 μmol min⁻¹·mg⁻¹ protein based on the oxidation of anthracene at pH 7.5 and 35 °C. Additionally, compositional analysis identified 4-benzyloxy-3-methoxybenzyl alcohol and 4-methylphthalaldehyde as anthracene metabolites by EM1, suggesting a novel anthracene degradation pathway.