Environmental stress response limits microbial necromass contributions to soil organic carbon

The majority of dead organic material enters the soil carbon pool following initial incorporation into microbial biomass. The decomposition of microbial necromass carbon (C) is, therefore, an important process governing the balance between terrestrial and atmospheric C pools. We tested how abiotic stress (drought), biotic interactions (invertebrate grazing) and physical disturbance influence the biochemistry (C:N ratio and calcium oxalate production) of living fungal cells, and the subsequent stabilization of fungal-derived C after senescence. We traced the fate of ¹³C-labeled necromass from ‘stressed’ and ‘unstressed’ fungi into living soil microbes, dissolved organic carbon (DOC), total soil carbon and respired CO₂. All stressors stimulated the production of calcium oxalate crystals and enhanced the C:N ratios of living fungal mycelia, leading to the formation of ‘recalcitrant’ necromass. Although we were unable to detect consistent effects of stress on the mineralization rates of fungal necromass, a greater proportion of the non-stressed (labile) fungal necromass C was stabilised in soil. Our finding is consistent with the emerging understanding that recalcitrant material is entirely decomposed within soil, but incorporated less efficiently into living microbial biomass and, ultimately, into stable SOC.     

响应曲面法优化高粱挤压最佳操作参数的研究

以高粱为原料,研究系统操作参数,包括:物料含水率、喂料速度、螺杆转速、机筒温度对目标参数的影响,并以响应曲面法优化最佳操作参数,优化得到的最佳操作参数为:物料含水率15.77%,喂料速度26.97r/min,螺杆转速181.20r/min,五区温度158.28℃。     

美味牛肝菌中油脂提取工艺的研究

采用超声波辅助法提取美味牛肝菌中的油脂，在单因素（提取时间、液料比和温度）实验考察的基础上，以油脂提取率为指标，通过响应面法对美味牛肝菌油脂的提取工艺进行优化。实验结果表明：响应面回归模型显著，拟合性好，可用于预测油脂提取率；优化后的油脂提取工艺为：液料比34.2 mL/g，温度36℃，提取时间4.5 h，此条件下油脂提取率为3.54826 %，与模型预测值相符，表明优化的油脂提取工艺合理。     

Preparation of Adjuvant Diluent for Live Vaccine against Classical Swine Fever and Evaluation of its Immune Effects

The aim of this study was to develop a novel oil-in-water (O/W) emulsion as adjuvant diluents (AD) for live vaccine against classical swine fever (CSF) that could effectively enhance the immune effect of vaccine.The AD was prepared by high-pressure homogenization technique.Formulations and preparation parameters were optimized with response surface design.Its stability, particle size, polydispersity (PDI) and Zeta potential were characterized.The humoral immune response and cellular immune response of the AD were evaluated with BALB/c mice by intramuscular injection.The particle size of the AD prepared by optimized formulation and parameters was 100.4 nm, PDI was 0.147, and Zeta potential was —28.7 mV.The experiment results showed that the AD had good stability.The AD was inoculated combined with live vaccine against CSF into BALB/c mice by intramuscular injection.The results showed that the live vaccine against CSF specific immune responses could be evoked in mice by co-inoculation with AD and vaccine.The cellular immune response levels in co-inoculated groups were significantly higher than control group (P<0.05), with obvious phenomena of higher levels of IFN-γ, IL-6 and IL-4 in serum.The result revealed that cellular immune capability significantly improved with the AD.The results strongly revealed that cellular immune capability significantly improved by introducing AD for effective immune-adjuvant for live vaccine against CSF.     

大球盖菇1号的分离纯化及其液体培养基优化

为缩短大球盖菇(Stropharia rugoso-annulata)1号液体种生长周期,提高菌丝体产量,为大球盖菇液体种工业化生产提供参考和依据。试验以大球盖菇1号菌丝球干质量(Y)为指标,通过Plackett-Burman设计试验,得出玉米粉、MgSO4和VB1对大球盖菇的生物量有显著影响,通过最陡爬坡试验和Box-Behnken响应面分析法对大球盖菇液体培养基组成进行优化,得到大球盖菇1号最适液体培养基为蔗糖20 g·L^-1、蛋白胨6 g·L^-1、酵母膏2 g·L^-1、KH2PO43 g·L^-1、MgSO44.56 g·L^-1、玉米粉4.25 g·L^-1、VB12.43 g·L^-1,通过对模型进行验证试验,大球盖菇1号菌丝生物量为1.2154 g·150-1mL-1,较基础培养基相比生物量提高36.2%,且数学模型的预测值与试验观察值相符,相对误差约为1.9%,证明响应面法优化大球盖菇1号液体培养基可行。     

腰带长体茧蜂对亚洲玉米螟幼虫的寄生功能反应

为评估腰带长体茧蜂Macrocentrus cingulum对亚洲玉米螟Ostrinia furnacalis的控害潜能，在实验室条件下（湿度60%~80%，光周期16L：8D）研究了20、24、28、32℃下腰带长体茧蜂对亚洲玉米螟幼虫的寄生功能反应和20、24、28℃下腰带长体茧蜂的自身密度干扰效应。结果表明：在20~32℃内，腰带长体茧蜂对亚洲玉米螟的寄生功能反应均符合Holling Ⅱ型；相同温度下，随着寄主亚洲玉米螟密度的增加，腰带长体茧蜂寄生量增加，但当寄主密度增加到一定数量后，寄生量趋于稳定。24℃的寄生效能最大，20℃最小。随着寄主亚洲玉米螟密度和腰带长体茧蜂密度的增加，搜寻效应逐渐降低。采用Hessell干扰模型，发现28℃时的搜寻常数Q和干扰效应m均为最大，腰带长体茧蜂个体间的干扰效应降低了其寄生效能。     

响应面法优化干热变性莲子淀粉膜制备工艺

以干热变性莲子淀粉为主要原料,研究变性淀粉用量、甘油用量和干燥温度对干热变性莲子淀粉膜性能的影响,并采用响应面分析及加权评价函数法对膜性能指标进行综合优化,得到干热变性莲子淀粉的最佳成膜工艺条件为:变性莲子淀粉用量为3.53%,甘油用量为1.51%,干燥温度80.61℃。本研究成果将为干热变性莲子淀粉可食膜的工业化生产提供理论指导。     

响应面法优化绿色木霉产孢子固体发酵培养基

为探讨绿色木霉固体发酵产孢子的最佳发酵培养基。运用响应面法设计试验,筛选出主要影响因子碳酸钙、硫酸铵及氯化锰,以孢子量为响应值建立二次回归方程,并借助Design Expert 8.0.6软件进行分析数据并确定优化条件。结果表明,在温度28℃,接种量15%,料水比1:0.70的培养条件下发酵7天,孢子量为8.505×10⁹CFU/g。通过优化,最终确定最佳发酵配方为：麸皮（过40目筛）50%,稻壳粉（过20目筛）30%,玉米粉（过80目筛）20%,硫酸铵1.08%,黄豆饼粉2.00%,玉米浆干粉2.00%,碳酸钙0.55%,氯化锰0.37%,pH 6.0~7.0。该配方所用原料廉价易得,发酵水平高,为大规模工业化生产提供保障。