Mg-based and Zn-based biodegradable materials have the potential to become the next-generation implant materials to treat bone diseases, because of their desired degradation and mechanical properties. This article reviews the status of these implant materials. The required properties of biodegradable materials such as biodegradability, mechanical properties, and biocompatibility for performance evaluation were briefly discussed. The influence of fabrication techniques, microstructure, alloying elements, and post-processing techniques on the properties of Mg and Zn-based materials was addressed. The degradation mechanism by dissolution, oxidation, and interaction with human body cells was discussed. The biocompatibility of Mg and Zn-based biodegradable materials was analyzed. The significance of in vitro and in vivo biocompatibility testing was highlighted, emphasizing the superiority of in vivo results over cell line studies. This article identifies the many Mg and Zn-based biodegradable materials and summarizes the key findings.

A degradation mechanism of polystyrene (PS) in mealworms reared on expanded PS (EPS) was investigated by its decrease in molecular weight and change in chemical structure. A 33% decrease in molecular weight was observed for the digested PS in the frass after 1 week of feeding to mealworms. The FT-IR and py-GC/MS spectra of the digested PS showed radical oxidative reactions taking place in the mealworm body. The presence of hydroperoxide, alcohol and phenol groups was confirmed, and dimer fragments of styrene with quinone and phenol groups were obtained. The decrease in molecular weight and the alternation of benzene rings indicated that autoxidation and quinonization via phenolic intermediates occurred simultaneously in the mealworm body. The survival rate of mealworms reared on EPS was higher than that of starved worms, indicating that EPS was a nutrient source. However, no weight gain was observed in mealworms fed EPS alone. Comparison with the mixed diets with bran or urethane foams (PU) indicated that protein, phosphorus and magnesium components absent from EPS were required for mealworm growth.

The Nanhai No. 1 shipwreck is an ancient wooden ship in the Southern Song Dynasty. Currently, serious challenges of microbial diseases exist on the hull wood. This study aimed to obtain microbial samples from the ship hull in December 2021 and analyze the microbial diseases through scanning electron microscopy and high-throughput sequencing to preserve the Nanhai No. 1 shipwreck. The biodegradation mechanism of diseased microorganisms was explored through whole genome sequencing and the detection of enzyme activity and gene expression levels of diseased microorganisms under different conditions. The results showed that there was obvious fungal colonization on the surface of the hull wood and Fusarium solani NK-NH1 was the dominant disease fungus on the surface. NK-NH1 has strong cellulose and lignin degradation ability. Its whole genome size is 52,389,955 bp, and it contains 17,402 genes. It has a variety of key enzyme genes involved in cellulose and lignin degradation. The NK-NH1 dominant degrading enzyme lignin peroxidase has the highest enzyme activity at pH = 4, NaCl concentration of 30%, and FeSO4 concentration of 50 mg/L, while laccase has the highest enzyme activity at pH = 4, NaCl concentration of 10%, and FeSO4 concentration of 100 mg/L. The above research results prove that NK-NH1 is a key fungus to the biodegradation of ship hull wood when it is exposed to air, low pH, high salt, and rich in sulfur iron compounds. This study provides a theoretical basis for the preservation of the Nanhai No. 1 shipwreck.

A cocultivation of the Pseudomonas mendocina with Actinomucor elegans was developed and investigated to improve the biodegradation of polylactic acid/polybutylene adipate-co-terephthalate (PLA/PBAT). And the coculture system could produce an efficient PLA/PBAT-degrading enzymes system to degrade PLA/PBAT films. The results showed that the protease activity (11.50 U/mL) and lipase activity (40.46 U/mL) of the coculture exceeded that of the monoculture (P. mendocina of 7.31 U/mL, A. elegans of 32.47 U/mL). The degradation rate of PLA/PBAT films using the coculture system was 18.95 wt% within 5 days, which was considerably higher than that of P. mendocina (12.94 wt%) and A. elegans (9.27 wt%) individually, suggesting that P. mendocina and A. elegans had synergistic degradation. In addition, P. mendocina and A. elegans could secrete proteases and lipases, respectively, which could catalyze the ester bonds of PLA1 and PBAT in PLA/PBAT films, respectively, and hydrolyze them into different monomers and oligomers as nutrition sources. Therefore, the PLA/PBAT films could be completely degraded. In this study, the PLA/PBAT films were efficiently degraded in the coculture system for the first time, which significantly improved the biodegradation of PLA/PBAT films.

Azo dyes pose hazards to ecosystems and human health and the cosubstrate strategy has become the focus for the bioremediation of azo dyes. Herein, Brilliant Crocein (BC), a model pollutant, was biodegraded by Providencia rettgeri domesticated from activated sludge. Additional ethanol, as a cosubstrate, could accelerate P. rettgeri growth and BC biodegradation, as reflected by the Gompertz models. This phenomenon was attributed to the smaller metabolites and greater number of potential pathways observed under the synergistic effect of ethanol. Genomic analysis of P. rettgeri showed that functional genes related to azo bond cleavage, redox reactions, ring opening and hydrolysis played crucial roles in azo dye biodegradation. Furthermore, the mechanism proposed was that ethanol might stimulate the production of additional reducing power via the expression of related genes, leading to the cleavage of azo bonds and aromatic rings. However, biodegradation without ethanol could only partly cleave the azo bonds.

The widespread detection of 17β-estradiol (E2) in the environment has become an emerging concern worldwide due to its endocrine disrupting effects. This work focuses on the aerobic and anaerobic biodegradations of E2 in various sedimentary environments with different availabilities of electron acceptors, including O2, NO3-, Fe3+, SO42-, or HCO3-. The highest removal efficiency (98.9%) and shortest degradation half-life of E2 (t1/2 = 5.0 d) were achieved under aerobic condition, followed by nitrate-reducing, ferric-reducing, sulfate-reducing and methanogenic conditions. We propose four different degradation pathways of E2 based on the metabolites identified under various redox conditions. Although most of E2 was effectively removed under aerobic condition, the potential environmental risk still needs to be considered due to the residual estrogenic activity induced by estrone (E1) formation. The endocrine-disrupting activities, as indicated by estradiol equivalent (EEQ) values, were related to E2 degradation rate and metabolite formation. We further analyzed the succession of bacterial community compositions and functions using Illumina HiSeq sequencing and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt). The findings herein evidenced that bacterial community compositions and metabolic functions associated with different redox conditions impact the biodegradation of E2 and its endocrine-disrupting activity. This knowledge will be useful in predicting the environmental fates of estrogenic hormones in various sedimentary environments and aid in establishing appropriate strategies for eliminating potential environmental risks.

In this study, oxytetracycline (OTC) as a target pollutant in swine wastewater was removed by aerobic granular sludge (AGS). The removal rate of 300 μg/L OTC in aerobic granular sludge sequencing batch reactor (AGSBR) increased to 88.00% in 33 days and maintained stable. The chemical oxygen demand (COD), ammonium nitrogen (NH4+-N) and total phosphorus (TP) in wastewater were also efficiently removed. The removal of OTC mainly depended on the adsorption and biodegradation of AGS, and the biodegradation was increased obviously after AGS adaptation to OTC. The degradation products of OTC were analyzed by mass spectrometry. The analysis of metagenome sequencing revealed that the enzymes, such as glycosyl transferases (GTs), polysaccharide lyases (PLs) and auxiliary activities (AAs), may play an important role in the removal of OTC. The Lefse analysis showed that the Flavobacteriia, Flavobacteriales, Cryomorphaceae and Fluviicola were four kinds of microbes with significant difference in OTC feed reactor, which are considered to be drug-resistant bacteria in AGSBR. Furthermore, the dynamics of microbial community changed significantly at three levels, including the enrichment of drug-resistant microorganisms and the microorganisms that gradually reduced or even disappeared under the pressure of OTC.

Shewanella oneidensis MR-1 degrades various azo dyes under microaerophilic and anaerobic conditions, but this process is inhibited under aerobic conditions. The mechanisms underlying azo dye biodegradation and inhibition remain unknown. Therefore, we investigated metabolic and transcriptional changes in strain MR-1, which was cultured under different conditions, to elucidate these mechanisms. At the transcriptional level, genes involved in certain metabolic processes, particularly the tricarboxylic acid (TCA) cycle, amino acid biodegradation, and the electron transfer system, were significantly altered (M ≧ 2, p > 0.8 ) in the presence of methyl orange (MO). Moreover, a high concentration of dissolved oxygen heavily impacted the expression levels of genes involved in fatty acid biodegradation. Metabolome analysis revealed significant alteration (p < 0.05) in the concentrations of nine metabolites when strain MR-1 was cultured under aerobic conditions; the majority of these metabolites were closely associated with amino acid metabolism and DNA replication. Accordingly, we propose a possible pathway for MO biodegradation and discuss the most likely causes of biodegradation inhibition due to dissolved oxygen.

The biodegradation effect and mechanism of decabromodiphenyl ether (BDE-209) by crude enzyme extract from Pseudomonas aeruginosa were investigated. The results demonstrated that crude enzyme extract exhibited obviously higher degradation efficiency and shorter biodegradation time than Pseudomonas aeruginosa itself. Under the optimum conditions of pH 9.0, 35 °C and protein content of 2000 mg/L, 92.77% of the initial BDE-209 (20 mg/L) was degraded after 5 h. A BDE-209 biodegradation pathway was proposed on the basis of the biodegradation products identified by GC-MS analysis. The biodegradation mechanism showed that crude enzyme extract degraded BDE-209 into lower brominated PBDEs and OH-PBDEs through debromination and hydroxylation of the aromatic rings.

Eutrophication has occurred frequently in various lakes and reservoirs, and the metabolic excretion produced during the algae growth causes serious water pollution and threatens ecological security. Biological control approaches such as screening bacteria with the capability to degrade cyanobacteria are an environment-friendly way. An isolated antialgal strain Streptomyces sp. KY-34, was applied to degrade the cyanobacterium Microcystis aeruginosa, and the possible biodegradation mechanism was investigated. The results showed that the fermentation liquor of Streptomyces sp. KY-34 could inhibit the growth of M. aeruginosa by restrained the synthesis of chlorophyll and photosynthetic pigments, and decreasing the contents of cellular protein and non-protein, accordingly led to the increase of malondialdehyde content, and the activities of superoxide dismutase, catalase and peroxidase in algae cells. In addition, the variation of the cellular ultrastructure indicated a serious change in algal physiology. It\'s revealed that the biodegradation mechanism of M. aeruginosa should primarily be that Streptomyces sp. KY-34 caused the damage of algae cell membrane and led to the increases of antioxidant enzymes, and then the growth of M. aeruginosawas inhibited.