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991.
《Journal of Asia》2021,24(4):1107-1115
Supermealworm, Zophobas atratus (Coleoptera: Tenebrionidae) is a tropical species used for human consumption and as an ingredient in animal feed. We investigated the hatching characteristics of Z. atratus eggs under varying conditions to optimize artificial rearing conditions. Overall, the average egg weight, width, and length decreased by 42.3%, 3.7%, and 10.1%, respectively, on the 6th day post-oviposition. We varied either temperature, photoperiod, illuminance, or humidity, while the other conditions remained constant. Of the four experimental temperatures—25 °C, 27 °C, 30 °C, and 33 °C–30 °C was associated with the highest hatching rate (91.0%) during days 5–7. Although other experimental conditions did not have a significant effect on hatchability, we were able to elucidate the ideal conditions for improved hatchability. For photoperiod, hatchability was the highest (84%) at 12L/12D, followed by 81.0% at 15L/9D, and 70% at 9L/15D. Among the illuminance conditions tested—600, 1800, and 3000 lx—hatchability was the highest at 1800 lx (82.3% on days 4–6). Among the relative humidity (RH) levels tested—50%, 65%, and 80%—hatchability was the highest at 65% RH (88.5% on days 5–6). Thus, the ideal conditions for maximum hatchability were 30 °C, 12L/12D, 65% RH, and 1800 lx. Under these combined conditions, the hatching rate increased by 93.6%, and the hatching time was reduced by two days.  相似文献   
992.
Tree root distribution and activity are determinants of belowground competition. However, studying root response to environmental and management conditions remains logistically challenging. Methodologically, nondestructive in situ tree root ecology analysis has lagged. In this study, we tested a nondestructive approach to determine tree coarse root architecture and function of a perennial tree crop, Theobroma cacao L., at two edaphically contrasting sites (sandstone and phyllite–granite derived soils) in Ghana, West Africa. We detected coarse root vertical distribution using ground‐penetrating radar and root activity via soil water acquisition using isotopic matching of δ18O plant and soil signatures. Coarse roots were detected to a depth of 50 cm, however, intraspecifc coarse root vertical distribution was modified by edaphic conditions. Soil δ18O isotopic signature declined with depth, providing conditions for plant–soil δ18O isotopic matching. This pattern held only under sandstone conditions where water acquisition zones were identifiably narrow in the 10–20 cm depth but broader under phyllite–granite conditions, presumably due to resource patchiness. Detected coarse root count by depth and measured fine root density were strongly correlated as were detected coarse root count and identified water acquisition zones, thus validating root detection capability of ground‐penetrating radar, but exclusively on sandstone soils. This approach was able to characterize trends between intraspecific root architecture and edaphic‐dependent resource availability, however, limited by site conditions. This study successfully demonstrates a new approach for in situ root studies that moves beyond invasive point sampling to nondestructive detection of root architecture and function. We discuss the transfer of such an approach to answer root ecology questions in various tree‐based landscapes.  相似文献   
993.
用响应面法对蜂房哈夫尼菌(Hafnia alvei)L-赖氨酸脱羧酶产酶诱导条件进行优化。首先通过单因素实验对产酶体系的pH、震荡培养时间、静置培养时间、诱导物添加量和Ⅷ添加量进行优化。在此基础上,用部分因子重复试验筛选出对酶活影响显著的3个因素(静置培养时间,诱导物添加量,VB6添加量),再通过Box-behnken实验对这三个因素进行优化,得出最优值。最终得到产酶最佳诱导条件为:震荡培养阶段培养基pH6.5,静置培养阶段pH5.5;摇床震荡培养11h后静置培养7.5h,诱导物L一赖氨酸加入量为5.18dL,维生素B6加入量为1.38g/L时酶活最高,达到71.2U/mL,为优化前(1.74u/mL)的41.8倍,在单因素的基础上提高了19%。  相似文献   
994.
徐静  吴少杰  阎斌伦  魏威 《微生物学通报》2012,39(12):1711-1719
【目的】从连云港高公岛沿岸海底泥样中分离筛选到一株产黑色素的海洋放线菌。【方法】对筛选得到的菌株HT-18所产的色素进行紫外-可见吸收光谱、红外光谱分析。通过形态特征、培养特征、生理生化测定以及16S rRNA序列的系统发育学分析确定菌株HT-18的分类学地位。采用单因素对产色素发酵条件进行优化。【结果】菌株HT-18所产色素为黑色素。鉴定该菌株属链霉菌属(Streptomyces)。最佳产色素条件为:初始pH7.0,装液量为70/250 mL,温度31°C,发酵时间为3 d。【结论】海洋链霉菌HT-18是一株具有研究和应用潜力的产黑色素菌株。  相似文献   
995.
培养条件对一株木霉产纤维素酶过程影响的研究   总被引:3,自引:0,他引:3  
采用固态发酵和连续监测正交实验结果的方法,研究了培养温度、初始pH值、液料比和接种量对一株木霉(Trichodermasp.)发酵过程中微晶纤维素酶活、CMC酶活和滤纸酶活的影响及影响程度。指出液料比在整个发酵过程中是对产酶影响最大的因素,温度在发酵初期影响较大,初始pH和接种量的影响均不显著。总体看来,培养温度、初始pH值、液料比和接种量分别为30℃、4、7和5%是比较合适的。  相似文献   
996.
Niu K  Zhang X  Tan WS  Zhu ML 《Bioresource technology》2011,102(15):7294-7300
In this work, metabolic flux analysis (MFA) method was used to estimate the effects of the culture conditions on both the producing and uptake hydrogen flux inside the cell of Klebsiella pneumoniae ECU-15. The results indicated that higher temperature could reduce the amount of the uptake hydrogen and enhance the hydrogen production from the NADH pathway. Moreover, both the producing hydrogen flux from formate and the uptake hydrogen flux were attained to the maximum at pH 7.0-7.5. The producing hydrogen flux was higher at 5 g/L initial glucose than that of the other concentrations, and the uptake hydrogen flux showed the minimum value under the same condition. The apparent hydrogen generation was caused by the combined action of producing hydrogenase, uptake hydrogenase and bidirectional hydrogenase. These results were helpful to deeply understand the mechanism of the biohydrogen evolving process and establish the suitable molecular strategies for improving hydrogen production.  相似文献   
997.
山地落叶阔叶林优势树种米心水青冈幼苗的定居   总被引:8,自引:4,他引:8  
郭柯 《应用生态学报》2003,14(2):161-164
在郁闭的林冠下、模拟林窗和林间空旷地3种光照环境中,研究了施肥和未施肥的米心水青冈幼苗生存和生长发育过程.结果表明,幼苗在林下的发育受到光照不足的严重抑制,生长在林下的幼苗比生长在林窗和空旷地幼苗死亡快,死亡率高,幼苗在郁闭林下能够生存的时间不超过12周.施肥处理的幼苗比对照的幼苗死亡快,死亡率高.幼苗死亡很可能与土壤中的病原生物有关.虽然由林下光照强度增加到模拟林窗的光照强度后,幼苗发育有明显改善,但幼苗在模拟林窗环境和空旷地的生长没有显著差异.结果说明,米心水青冈新出土的幼苗在郁闭林冠下易受伤害,更新立苗阶段需要有比较好的光照条件,肥沃土壤可能也无助于改善郁闭林冠下幼苗的定居.  相似文献   
998.
陆生植物自身能否排放甲烷?   总被引:2,自引:0,他引:2  
一般认为自然来源的甲烷是在厌氧环境下形成的,而最近研究却发现在有氧环境下植物自身也能释放甲烷,这将对全球甲烷收支产生重大影响。但这一发现目前还存在很大争议,一些研究证实植物在有氧环境下能排放甲烷,果胶、聚半乳糖醛酸等含甲氧基官能团的组分是植物产生甲烷的主要来源物质,甚至纤维素、木质素等植物结构组分也能排放甲烷;而另一些研究却发现植物并不能排放甲烷或者排放速率极小,而观测到的植物甲烷排放可能来自于土壤中,即溶解有甲烷的土壤水分被被植物吸收并通过蒸腾或蒸发作用而排放到大气中。有氧环境下植物排放甲烷的机制仍不清楚,光照、温度、紫外辐射、机械损伤等环境胁迫可能是导致植物排放甲烷的重要原因,但这些因素的影响作用仍存在很大的不确定性。即使如此,一些研究仍对全球或区域植物甲烷排放的通量进行了估算,估计全球植物甲烷排放通量为10-236Tg.a-1。未来研究应在更多地区针对不同生境的各种植物是否排放甲烷进行独立检验,并在此基础上探讨植物排放甲烷的机制。  相似文献   
999.
Seeds of milk thistle (Silybum marianum L. Gaertner) contain silymarins and ca. 25% (w/w) of oil. A pre-treatment step involving refluxing with petroleum ether is usually performed before extraction of the silymarins using organic solvents. This paper compares the extraction of whole and defatted milk thistle seeds in various solvents as a function of temperature. The extraction of whole seeds of milk thistle with water at 50, 70 and 85 degrees C was also examined: the yield of silymarin increased with increasing water temperature. In most cases, ethanol at 60 degrees C recovered the largest quantities of silymarins. However, boiling water proved to be an efficient extraction solvent for the more polar silymarins such as taxifolin and silychristin, even when using whole seeds. Extractions of defatted seed meal with boiling ethanol returned maximum yields of 0.62, 3.89, 4.04, and 6.86 mg/g defatted seed of taxifolin, silychristin, silybinin A and silybinin B, respectively. When extracting defatted seed meal with ethanol, yields of taxifolin, silybinin A and silybinin B were, respectively, 6.8-, 0.95-, 1.7- and 1.6-fold higher than when extracting whole seeds. When extracting with boiling water, the yields of silychristin, silybinin A, and silybinin B were 380, 47 and 50% higher for whole seeds compared with defatted seeds.  相似文献   
1000.
响应面法优化自养小球藻产生物柴油油脂   总被引:4,自引:1,他引:4  
利用响应面法对小球藻(Chlorella vulgaris)在2L气升式生物反应器中对自养产生物柴油油脂的培养条件进行了优化。首先用Plackett-Burman方法对10个相关影响因素的效应进行评价并筛选出对产油有显著影响的3个因素:KNO3浓度、温度和CO2浓度;再用最陡爬坡实验逼近最大产油区域;最后由中心组合实验及响应面分析确定了影响产油主要因素的最佳条件为:KNO3浓度0.31g/L,温度26.5℃,CO2浓度6.80%,最高产油量达到0.42g/L,比优化前提高了近2倍。优化后,在10L气升式生物反应器中进行了扩大培养。  相似文献   
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