Room temperature NH3 gas sensor based on In(OH)3/Ti3C2Tx nanocomposites.

Industrialization and agricultural demand have both improved human life and led to environmental contamination. Especially the discharge of a lot of poisonous and harmful gases, including ammonia, ammonia pollution has become a pressing problem. High concentrations of ammonia can pose significant threats to both the environment and human health. Therefore, accurate monitoring and detection of ammonia gas are crucial. To address this challenge, we have developed an ammonia gas sensor using In(OH)3/Ti3C2Tx nanocomposites through an in-situ electrostatic self-assembly process. This sensor was thoroughly characterized using advanced techniques like XRD, XPS, BET, and TEM. In our tests, the I/M-2 sensor exhibited remarkable performance, achieving a 16.8% response to 100 ppm NH3 at room temperature, which is a 3.5-fold improvement over the pure Ti3C2Tx MXene sensor. Moreover, it provides swift response time (20 s), high response to low NH3 concentrations (≤ 10 ppm), and excellent long-term stability (30 days). These exceptional characteristics indicate the immense potential of our In(OH)3/Ti3C2Tx gas sensor in ammonia detection.

Isolation of a novel feather-degrading Ectobacillus sp. JY-23 strain and characterization of a new keratinase in the M4 metalloprotease family.

Microbial keratinases have prominent potential in biotransformation of recalcitrant keratin substrates to value-added products which has made keratinases a research focus in the past decades. In this study, an efficient feather-degrading bacterium was isolated and identified as a novel species in Ectobacillus genus and designated as Ectobacillus sp. JY-23. The degradation characteristics analysis revealed that Ectobacillus sp. JY-23 could utilize chicken feathers (0.4% w/v) as the sole nutrient source and degraded 92.95% of feathers in 72 h. A significant increase in sulfite and free sulfydryl group content detected in the feather hydrolysate (culture supernatant) indicated efficient reduction of disulfide bonds, which inferred that the degradation mechanism of isolated strain was a synergetic action of sulfitolysis and proteolysis. Moreover, abundant amino acids were also detected, among which proline and glycine were the predominant free amino acids. Then, the keratinase of Ectobacillus sp. JY-23 was mined and Y1_15990 was identified as the keratinase encoding gene of Ectobacillus sp. JY-23 and designated as kerJY-23. Escherichia coli strain overexpressing kerJY-23 degraded chicken feathers in 48 h. Finally, bioinformatics prediction of KerJY-23 demonstrated that it belonged to the M4 metalloprotease family, which was a third keratinase member in this family. KerJY-23 showed low sequence identity to the other two keratinase members, indicating the novelty of KerJY-23. Overall, this study presents a novel feather-degrading bacterium and a new keratinase in the M4 metalloprotease family with remarkable potential in feather keratin valorization.

Highly selective NH3 gas sensor based on Co(OH)2/Ti3C2T x nanocomposites operating at room temperature.

Ammonia (NH3) is a common air pollutant and is a biomarker for kidney disease. Therefore, the preparation of ammonia gas sensors with high sensitivity, good selectivity and low operating temperature is of great importance for health protection. Using the in situ electrostatic self-assembly approach, a chemoresistive gas sensor based on Co(OH)2/Ti3C2T x hybrid material was created in this study. The prepared samples were characterized by XRD, XPS, TEM, BET and other testing methods for structure, surface topography and elements. These samples were fabricated into sensors, and the gas sensing properties of the materials were investigated under different test conditions. The results show that the gas response value of the C/M-2 sensor is up to about 14.7%/100 ppm, which is three times the response value of the sensor made of pure MXene to NH3. In addition, the Co(OH)2/Ti3C2T x hybrid sensors exhibit excellent repeatability, high sensitivity under low concentration (less than 5 ppm), fast response/recovery time (29 s/49 s) and long-time stability, which indicates their promising utility in the IoT field.

Dynamics of the Bacterial Community's Soil During the In-Situ Degradation Process of Waste Chicken Feathers.

Bacteria play an important role in the biodegradation of feather waste. The exploration of the related microbial community structure and diversity is essential to improve the performance of feather waste treatment processes. In the present work, an in-situ soil sampled from a poultry farm was directly used to simulate and accelerate the natural degradation processes of feather waste under laboratory conditions, in which the dynamics of the microbial communities was further analyzed by Illumina HiSeq high-throughput 16S rRNA gene sequencing. Biochemical factors, including pH, feather degradation rate and soluble protein content were also determined in this study. The biochemical results showed that the in-situ soil exhibited an effective degradability on chicken feathers, and the degradation rate of feathers reached 57.95 ± 3.09% at 120 h of cultivation. Meanwhile, soluble protein content and pH reached 33.62 ± 1.45 mg/mL 8.99 ± 0.08, respectively. The results of bacterial diversity analysis showed that bacterial community structure and composition significantly varied in each phase of degradation. Additionally, the bacteria system with feather degradability might consist of Bacillus, Chryseobacterium, Lysobacter, Brevibacillus, and Stenotrophomonas genera. This system may include the following key pathways: carbohydrate metabolism, amino acid metabolism, nucleotide metabolism, membrane transport, replication and repair, translation, signal transduction and energy metabolism. Moreover, the bacterial communities may occur community succession during the degradation processes of chicken feathers. In summary, the present work provided valuable insights into the understanding of microbial community and metabolic functions for feather degradation, although the in-situ biodegradation process was conducted under laboratory conditions. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-021-00996-6.

Antifungal Action of Antifungalmycin N2 Against Rhizoctonia solani by Disrupting Cell Membrane and Inhibiting Succinate Dehydrogenase.

Antifungalmycin N2 (3-methyl-3,5-amino-4-vinyl-2-pyrone, C6H7O2N) was a novel structural antifungal metabolite produced by Streptomyces sp. strain N2. Our previous study reported that the antagonistic interaction between antifungalmycin N2 and Rhizoctonia solani was accompanied by an oxidative stress in R. solani cell, indicating a probable damage occurred in the cell membranes and mitochondria. To verify this, the present study focused on investigating the effects of antifungalmycin N2 on the structure and function of cell membranes and mitochondria of R. solani. Morphological observations in transmission electron microscopy and fluorescence microscope showed that cell membranes of R. solani were damaged, and its cytoplasmic organelles were disorganized when treated with antifungalmycin N2. Meanwhile, the kinetics of membrane-related physiological and biochemical parameters, such as the increased malondialdehyde level, dropped ergosterol formation, and enhanced electrical conductivity in R. solani mycelia, further confirmed that antifungalmycin N2 would disrupt the cell membrane structure and function. More significantly, antifungalmycin N2 had a significantly inhibitory effect on the succinate dehydrogenase (SDH) activity of R. solani, and indicated that the mode and site of action of antifungalmycin N2 against R. solani might be similar to the existing succinate dehydrogenase inhibitors fungicides by binding in the ubiquinone-binding site. In conclusion, the above results demonstrated that the mode and site of action of antifungalmycin N2 targeted to cell membrane and SDH of R. solani, thus exerting the antifungal activity by damaging cell membrane structure and function, together with inhibiting the SDH activity.

Antagonistic activity and mechanism of an isolated Streptomyces corchorusii stain AUH-1 against phytopathogenic fungi.

The various diseases that occur during the growth of plants usually cause a significant reduction in production and quality of agricultural products. Actinomycetes, especially Streptomyces spp., become a valuable biological control resource due to their preponderant abilities to produce various secondary metabolites with novel structure and remarkable biological activity. The present work aimed to isolate an effective antagonistic actinomycete against various soilborne phytopathogenic fungi. By dual culture with Fusarium oxysporum f. sp. niveum, an antagonistic actinomycete named Streptomyces corchorusii stain AUH-1 was screened out from 26 soil samples. The in vitro bioassay results showed that S. corchorusii stain AUH-1 had a broad-spectrum antagonistic activity against a range of fungal plant pathogens, such as F. oxysporum f. sp. niveum, Phytophthora parasitica var. nicotianae, Rhizoctonia solani, P. capsica, Botryosphaeria dothidea, F. oxysporum f. sp. vasinfectum, Verticillium dahliae, and F. oxysporum f. sp. cucumerinum. According to the morphological observations in scanning electron microscopy (SEM) and fluorescence microscope (FM), it was found that the cell membranes of F. oxysporum f. sp. niveum were damaged when treated with the antifungal metabolite form S. corchorusii stain AUH-1. Meanwhile, the dropped ergosterol formation and increased malondialdehyde levels further confirmed that S. corchorusii strain AUH-1 exerted its antagonistic activity against F. oxysporum f. sp. niveum via damaging the structure and function of cell membranes. In conclusion, S. corchorusii strain AUH-1 showed a promising prospect for the development of biological agent, especially due to its broad-spectrum and effective antagonist on various soil-borne plant pathogens.

[Effects of temperature and pH on digestive enzymes activities in Whitmania pigra].

OBJECTIVE: Current study was conducted to investigate and compare the impact of temperature and pH on the activities of amylase, protease and lipase in alimentary tract of Whitmania pigra. METHOD: The responses of amylase, protease, and lipase activities were determined over a wide range of temperatures (7-52 degrees C) and pH gradient (2.2-11.2). RESULT: The highest lipase activity was found under 37 degrees C, pH 8.2, and the highest amylase activity was detected under 37 degrees C, pH 5.2, while protease activity peaked at 42 degrees C, pH 3.2 or pH 9.2. CONCLUSION: The optimal temperature in alimentary tract of Wh. pigra for lipase and amylase was 37 degrees C, and the responding temperature for protease was 42 degrees C. The optimal pH value in alimentary tract of Wh. pigra for lipase and amylase was pH 8.2 and pH 5.2, respectively. While pH 3.2 or 9.2 seems to be both favorable for high protease activity.