The capability of the algaeChlorella vulgaris andScenedesmus obliquus of utilizing amino acids as the sole nitrogen source

The capability of utilizing 20 amino acids and 2 amides as the sole nitrogen source for growth was studied in two green algae (Chlorophyceae). A comparison was made of the growth rate of algae in a mineral nutrient solution containing nitrate as the nitrogen source, with that in the same solution in which nitrogen in the form of nitrate was substituted by an equivalent nitrogen amount in the form of various amino acids. In addition to this, another series of experiments was carried out in whioh both culture media were supplied with glucose. The results show that both algae utilize a series of amino acids in dependence of their structure (mostly 3-carbon amino acids). The growth rate ofChlorella in the presence of these sources is the same as in nitrate, that ofScenedesmus even much higher. In the cultures containing glucose both algal species exhibit a higher growth rate in the media with the nitrate nitrogen source than in those with amino acids (with the exception of glycine inScenedesmus).     

Recovery from ethyl methanesulphonate-induced genetical damage in barley. Independence of sodium azide treatment

Barley seeds were treated for 3 h at 25°C with 240 mM ethyl methanesulphonate (EMS), washed for 18 h, treated with various concentrations of unbuffered sodium azide (pH 6.7–7.3) for 3 h at 25°C, re-dried to 30% water content and either sown immediately or stored at 25°C for 12 days and then sown. The synergistic action of sodium azide post-treatment has been demonstrated only for the EMS-induced M₁ germination reduction, while the EMS-induced M₁ sterility and the yield of M₂ chlorophyll mutants were unaffected. The ?storage” recovery from EMS-induced mutagenic effects was insensitive to sodium azide post-treatment. The 12 day-seed storage at 25°C brought about an improvement of M₁ germination, M₁ survival, M₁ fertility and a decrease in the amount of M₂ mutants, regardless of whether sodium azide post-treatment was applied or not.     

基于地表水与地下水分割校正的漓江流域水供给服务时空格局研究

喀斯特区域水循环过程与其他地区存在显著区别,其水供给服务也具有独特的空间分布特征。然而,目前针对喀斯特地区产水量的时空变化研究较少考虑喀斯特生态系统的特殊性,导致产水量的空间模拟结果存在一定偏差。根据喀斯特地貌形态和地下水补径排泄特征提出了一种产水量分割方法,并基于水量平衡原理建立了地表水与地下水分割校正概念模型。选取喀斯特山区典型区域漓江流域为研究区,通过上述方法校正了InVEST模型产水量模拟结果,从栅格、地貌分区和子流域3个尺度分析了漓江流域2000—2020年产水量校正前与校正后时空分布格局。研究结果表明：(1)漓江流域2000—2020年InVEST模型产水量呈现先减后增再减的趋势,水供给服务空间分布格局为北高南低。产水深度在岩溶区和非岩溶区几乎没有差异,但在岩溶区内部差异明显：裸露型岩溶区产水深度高于覆盖型和埋藏型,峰林平原产水深度高于峰丛洼地。子流域分区平均产水深度排序为漓江上游区>漓江中游区>恭城河区>荔浦河区>漓江下游区。(2)利用地表与地下水分割校正后,水供给服务空间分布格局为四周高于中部,西北部高于东南部。非岩溶区产水深度明显高于岩溶区,埋...     

根际微生态调控白菜根肿病发生的机制研究进展

白菜根肿病是由芸薹根肿菌(Plasmodiophora brassicae Woron)引起的一种常见土传病害,主要危害白菜的根部。根际是土壤-植物-微生物相互作用最活跃的关键微域,根际微生态系统中的微生物失衡是导致土传病害的重要因素,深入探究根际微生态与土传病害互作机制,有利于从根际微生物、抑病物质和功能代谢等方面挖掘防控土传病害安全高效的方法。本文综述了根际微生态与白菜根肿病的发生机制关系,从该病害的危害、发生的根际微生态机制及生防菌防治研究等方面综合分析了根际微生物调控白菜根肿病发生的机制,以期为白菜根肿病防控、促进土壤健康和维持根际微生态系统稳定提供理论依据。     

一株抗茶炭疽菌和魔芋镰刀菌的淀粉酶产色链霉菌的分离、鉴定及生防潜能

【背景】放线菌是一类重要的生防菌,具有强大的代谢活性,能产生抗生素、酶、酶抑制剂和激素等天然产物抑制病原物生长。【目的】从茶树根际分离得到放线菌,研究候选放线菌对茶炭疽菌和魔芋镰刀菌的抑菌活性及其生防潜能。【方法】分别以茶炭疽病致病菌Colletotrichum camelliae和魔芋茎腐病致病菌Fusarium solani为指示菌,采用土壤稀释涂布法、平板对峙法和菌丝生长速率法,从茶树根际土壤中分离、筛选拮抗放线菌,并根据菌株的形态特征、生理生化特性和系统发育分析结果对其进行分类鉴定,并开展候选放线菌的产促生相关物质和分泌细胞壁水解酶能力的定性检测试验。【结果】共分离得到14株拮抗放线菌,菌株A-dyzsc04-2的拮抗效果最强,被鉴定为淀粉酶产色链霉菌（Streptomyces diastatochromogenes）。该菌株的活菌体对C. camelliae和F. solani的抑制率分别为66.71%±1.23%和71.59%±2.46%,其无菌发酵滤液对2种指示菌的抑菌率均大于90%;此外,菌株A-dyzsc04-2还具有产嗜铁素和葡聚糖酶以及溶解无机磷的能力。【结论】菌株A-dyzsc04-2是一株优良的生防菌,具有较高的开发利用价值,研究结果为菌株A-dyzsc04-2防治茶炭疽病和魔芋茎腐病提供了理论支撑。     

Black soldier fly (Hermetia illucens) larvae oil as an alternative fat ingredient to soybean oil in laying hen diets

ObjectiveThe objective of this study was to determine whether dietary black soldier fly (Hermetia illucens, HI) larvae oil (HILO) could serve as an alternative fat source to soybean oil (SBO) in laying hen diets.MethodsWe randomly assigned 25-week-old Hy-line Brown laying hens (n = 144) to receive (n = 6 hens/group; eight replicates) a control or an experimental diet in which SBO was replaced with 50% (50HILO) or 100% HILO (100HILO).ResultsDietary HILO did not negatively affect body weight or productive performance during the study. The eggs also had similar quality parameters, proximate composition, and cholesterol levels. However, the yolk color index was significantly higher (p<0.01) in the 100HILO than in the other groups. Dietary HILO significantly altered the composition of fatty acids (FAs) in abdominal fat and eggs. Total saturated fatty acids (SFAs) and total polyunsaturated FAs (PUFAs) were significantly increased and decreased in the 50HILO and 100HILO groups, respectively, compared with those in the control group (p<0.001 and p<0.0001, respectively). Specifically, the medium-chain FAs lauric and myristic acids were remarkably increased in the abdominal fat of laying hens fed HILO (p<0.0001), whereas only myristic acid increased in eggs (p<0.0001). Undesirable heavy metal (aluminum, fluorine, arsenic, lead, mercury, and cadmium) concentrations were below permissible limits in eggs.ConclusionWe considered that HILO could be an alternative dietary fat to SBO for laying hens with maintained productive performance and good egg quality.