Detoxification of Ochratoxin A by a novel Aspergillus oryzae strain and optimization of its biodegradation.

The mycotoxin Ochratoxin A (OTA) causes serious health risks and is found in food products throughout the world. The most promising method to detoxify this compound is biodegradation. In this study, Aspergillus oryzae strain M30011 was isolated and characterized based on its considerable capacity to degrade OTA. The degradation product (compound I) of A. oryzae-treated OTA was isolated, and its toxicity response was also evaluated. Furthermore, the relationships between three key cultivation condition factors affecting the OTA degradation rate were examined using the response surface methodology (RSM). Compound I was identified as ochratoxin α (C11H9O5Cl), and the toxicity response experiments indicated that A. oryzae detoxified OTA to a great extent. A maximum degradation rate of 94% was observed after 72h. This study demonstrates the potential for using A. oryzae to detoxify OTA and suggests that it could be applied in the food industry to improve food safety and quality.

[Structural Characteristics of Micro-nano Particle Size Biochar and Its Adsorption Mechanism for Cd2].

The aim of this study was to investigate the structural characteristics of biochar with different micro/nano particle sizes and its effect on the adsorption performance of Cd2+. Corn stalk biochar with different particle sizes (180-250 µm, 50-75 µm, and ≤ 20 µm, denoted as BC-1, BC-2, and BC-3, respectively) were prepared using the sieving and ball milling method. The structural properties of different particle sizes of biochar were analyzed via elemental analysis, laser particle size analysis, SEM, BET, FTIR, and XPS. Additionally, the adsorption mechanisms of Cd2+ by three particle sizes of biochar under initial Cd2+ concentrations, adsorption times, and pH conditions were comparatively studied using static adsorption experiments. The results showed that with the decrease in particle size, the pH and zeta potential of biochar were reduced; the aromaticity and polarity decreased; the specific surface area and pore volume increased; and the intensity of the characteristic peaks containing OH, C[FY=,1]C/C[FY=,1]O, and C-O groups increased. The adsorption kinetics of Cd2+ with different particle diameters of biochar were in accordance with the pseudo-secondary kinetic model, with chemisorption dominating. The equilibrium times were in the decreasing order of BC-1 (540 min)>BC-2 (360 min)>BC-3 (80 min). The Langmuir model could better fit the adsorption isotherm process of Cd2+ on biochar of different particle sizes (R2>0.97), and the maximum adsorption capacity of Cd2+ increased with the decrease in particle size, which was expressed as BC-3 (74.43 mg·g-1)>BC-2 (45.71 mg·g-1)>BC-1 (44.59 mg·g-1). The main mechanisms of Cd2+adsorption by biochar were electrostatic attraction, surface complexation, and cation-π interaction.

[Effects of straw incorporation on rice carbon sequestration characteristics and grain yield formation].

A field experiment was conducted to study the effects of straw incorporation on rice dry matter accumulation and transportation, rice carbon sequestration and grain yield formation. The experiment included four levels of straw incorporation: 0 (control), 4000, 6000 and 8000 kg · hm(-2). Hybrid rice cultivar Zhongzheyou 1 was used in this experiment. The results showed that the average rice dry matter accumulation amount of the three straw incorporation treatments was increased by 63.03 g · m(-2) compared with the control, and that of straw incorporation of 6000 kg · hm(-2) showed the most favorable result, which was 154.40 g · m(-2) higher than the control. Effects of straw incorporation on rice dry matter accumulation showed the best performance from the maximum tillering stage to the full heading stage, and the dry matter accumulation at this stage was 71.25 g · m(-2) higher than the control. Compared with the control, the average dry matter exportation rate and apparent transformation rate from rice stem and leaf in the straw incorporation treatments were increased by 4.2% and 3.7%, respectively. The highest dry matter exportation rate and apparent transformation rate from rice stem and leaf were observed in the straw incorporation treatment of 6000 kg · hm(-2), which were increased by 12.8% and 11.1% compared to the control, respectively. The average rice carbon sequestration from the straw incorporation treatments was increased by 55.38 g · m(-2) compared with the control, and straw incorporation of 6000 kg · hm(-2) performed best with an increase of 17.8% compared with the control. Straw incorporation played a positive role in regulating the carbon sequestration of stem and leaf at the early growth stage and carbon sequestration of spike at the late growth stage. The average grain yield from the straw incorporation treatments was increased by 794.59 kg · hm(-2) (9.5% higher) compared with the control. Rice grain yields from the straw incorporation treatments of 6000 and 4000 kg · hm(-2) were significantly higher than the control, while rice grain yield from the straw incorporation treatment of 8000 kg · hm(-2) did not show a significant increase compared to the control. The rice grain yield was closely related to the yield components, and the increase of effective panicles may be the main reason for the higher grain yields in the straw incorporation treatments. Effective panicles in the straw incorporation treatments was averagely 8.41 spikes · m(-2) more than the control.