Isolation and characterization of a thermophilic Bacillus shackletonii K5 from a biotrickling filter for the production of polyhydroxybutyrate

Polyhydroxyalkanoates（PHAs） are aliphatic polyesters accumulated intracellularly by both Gram-negative and Gram-positive bacteria. However, compared to the PHAs of Gramnegative bacteria, few endotoxins（lipopolysaccharides, LPS）, which would be co-purified with PHAs and cause immunogenic reactions, are found in the PHAs produced by Gram-positive bacteria. A thermophilic Gram-positive bacterium K5, which exhibited good growth and polyhydroxybutyrate（PHB）-accumulating ability, has been isolated and characterized from a biotrickling filter designed for the removal of NOx from flue gas in a coal-fired power plant in China. Based on the biochemical characterization and 16 S rRNA gene sequence（Genbank accession no. JX437933）, the strain K5 has been identified as Bacillus shackletonii, which has rarely been reported in the literature, and this report is the first time that B. shackletonii has been found to accumulate PHB. The strain K5 was able to utilize glucose as carbon source to synthesize PHB at a broad range of temperatures（from 35 to 50 °C）, and the ideal temperature was 45 °C. The strain K5 could effectively yield PHB of up to 69.9% of its cell dry weight（CDW）（2.28 g/L） in flask experiments employing glucose as carbon source at 45 °C, followed by 56.8% and 52.3% of its CDW when using sodium succinate and glycerol as carbon source, respectively. For batch cultivation, the strain K5 was able to produce PHB of up to 72.6% of its cell dry weight（9.76 g/L） employing glucose as carbon source at 45 °C and pH 7.0.     

荒漠蓝藻抗逆性及应用研究进展

蓝藻是荒漠藻类中的主要类群,它能抵御荒漠生境中高低温、干旱、高盐碱、高紫外辐射等极端环境的胁迫,蓝藻胞外多糖及胞内的伪枝藻素、MAAs等在抵抗逆境胁迫过程中起了重要的作用.主要介绍了荒漠蓝藻抗逆性及其培养条件的研究进展,并概述了荒漠蓝藻的应用研究.     

连续流态下以实际低基质生活污水培养好氧颗粒污泥及其脱氮性能

研究了连续流系统污泥颗粒化过程中COD、氨氮和TN的去除效果以及成熟好氧颗粒污泥的物理性质和脱氮动力学.结果表明40 d内连续流系统内能形成好氧颗粒污泥.随着颗粒化程度的提高,系统脱氮除碳性能有所增加;第41~60 d稳定运行期间,系统对COD、氨氮和TN的平均去除率分别到达到85.54%、95.5%和65.56%,且反应过程中硝酸盐氮和亚硝酸盐氮的积累不高.成熟颗粒污泥有较多的空隙结构,含有大量的胞外聚合物,相比于接种絮状污泥,其含水率、湿密度、沉降速度、机械强度、SVI值等都体现出了明显的优势.成熟好氧颗粒污泥同步硝化反硝化效率为81.69%,硝化速率(以NH+4-N计)和反硝化速率(以NO-x-N计)分别为5.78 mg·(L·h)-1和4.90 mg·(L·h)-1.     

乌梁素海东部流域非生长季草地土壤细菌群落结构的垂向差异

草地是区域生态系统的关键组成部分,其土壤细菌群落结构在元素迁移及生态多样性系统中发挥着重要作用.为对比分析寒旱区典型草地土壤中细菌群落的空间结构差异,在5月初(新的生长季开始之前,即非生长季),对内蒙古乌梁素海东部流域草地土壤样品进行了采集,获得不同区域30 cm和60 cm深度土壤样品各5个,利用16S rRNA高通量测序方法对样品细菌群落结构进行了分析.结果显示：(1)Actinobacteriota、 Proteobacteria、 Chloroflexi、 Acidobacteriota、 Gemmatimonadota、 Planctomycetota、 Methylomirabilota和Crenarchacota等菌门在30 cm和60 cm样品中相对丰度占比均超过1%,且60 cm样品中相对丰度高于30 cm样品的优势菌门有6个,优势菌属有5个,OTU则为8个.不同深度样品中优势菌门、菌属乃至OTUs的相对丰度变化和其在细菌群落结构中的贡献性趋势并不完全对应;(2)来源于Armatimonadota和Verrucomicrobiota门的norank＿f＿＿norank...     

The Dual Model for Tourism Resource Productivity Improvement

Abstract

For natural resource science, resource productivity studying is an important subject. But researches on tourism resource productivity are limited. The most significant influencing factor on tourism resource productivity is the potential market scale of tourist locations, and second most important influencing factor is the resource endowment. Regional urban population is significantly correlated with region tourist numbers, being the decisive factor of region potential tour market scale. In tourism development, the dual model should be adopted: on one hand to enhance tour spot attractiveness, on the other hand to cultivate the potential market by improving urbanization level and other means. In the situation of tourism development fever spreading, the dual model for improving tourism productivity helps to avoid the “Great Leap Forward” which means that too rapid tourism construction divorces from actual market demand.     

Response of soil CO2 efflux to precipitation manipulation in a semiarid grassland

Soil CO_2efflux(SCE) is an important component of ecosystem CO_2 exchange and is largely temperature and moisture dependent, providing feedback between C cycling and the climate system. We used a precipitation manipulation experiment to examine the effects of precipitation treatment on SCE and its dependences on soil temperature and moisture in a semiarid grassland. Precipitation manipulation included ambient precipitation, decreased precipitation(- 43%), or increased precipitation(+ 17%). The SCE was measured from July2013 to December 2014, and CO_2 emission during the experimental period was assessed.The response curves of SCE to soil temperature and moisture were analyzed to determine whether the dependence of SCE on soil temperature or moisture varied with precipitation manipulation. The SCE significantly varied seasonally but was not affected by precipitation treatments regardless of season. Increasing precipitation resulted in an upward shift of SCE–temperature response curves and rightward shift of SCE–moisture response curves,while decreasing precipitation resulted in opposite shifts of such response curves. These shifts in the SCE response curves suggested that increasing precipitation strengthened the dependence of SCE on temperature or moisture, and decreasing precipitation weakened such dependences. Such shifts affected the predictions in soil CO_2 emissions for different precipitation treatments. When considering such shifts, decreasing or increasing precipitation resulted in 43 or 75% less change, respectively, in CO_2 emission compared with changes in emissions predicted without considering such shifts. Furthermore, the effects of shifts in SCE response curves on CO_2 emission prediction were greater during the growing than the non-growing season.     

自然水体中铁-锰氧化细菌的研究

通过在河流中悬吊自行设计的载玻片架,获取了具有由铁-锰氧化细菌产生的特异的铁锰氧化物结构的生物膜,设计了4种培养基,采用2种不同的细菌分离方法,对生物膜上的铁细菌进行分离,应用荧光X射线分析仪(XRF)分析了分离菌株产物的化学元素组成,并对分离菌株的铁锰氧化形态进行了观察.研究发现,铁细菌2号培养基为合适的分离培养基;采用平板涂布法分离出的2株氧化铁和锰的细菌,经系统发育地位的分析确定为纤发菌属;对运动纤发菌的产物分析确定无定形铁和锰为其主要金属元素;形态观察确定霍氏纤发菌呈树枝状鞘结构,而运动纤发菌呈蛛网状鞘结构.采用原位培养法分离出1株具有独特铁锰氧化物结构的细菌,经基因序列比对,确定为丛毛菌属.该实验获得的3株铁-锰氧化细菌的序列为设计针对于自然水体中的铁-锰氧化细菌FISH探针及PCR引物提供了关键数据.     

柴河小流域草地土壤环境的同位素示踪研究

以滇池柴河小流域为研究区域,于2011年7月采集草地样品全样、分层样共17个,对土壤粒度、w(SOM)(SOM为有机质)、w(TN)进行测定;采用放射性核素137Cs示踪技术估算研究流域土壤侵蚀速率;同时,测定δ13C(稳定性碳同位素丰度),以研究该流域生态环境状况. 结果表明:①土壤粒度组成为粉粒(66.74%~77.55%)>黏粒(21.22%~31.29%)>砂粒(1.23%~3.33%),同一土地利用方式的土壤粒度组成差异较小,土壤适宜耕作. ②CH1、CH2、CH3采样点的w(SOM)分别为3.51%、1.72%、2.54%,w(TN)分别为0.22%、0.17%、0.18%,二者相对偏低,并且土壤剖面的w(SOM)、w(TN)均随深度增加呈降低趋势. ③CH1、CH2、CH3采样点的137Cs含量分别为586.91、279.83和217.82bq/m2,侵蚀模数分别为324.96、879.33和1066.83t/(km2·a),表明研究区整体属于轻度侵蚀且表层土壤侵蚀较为严重. ④CH1、CH2、CH3采样点的δ13C平均值分别为-18.49‰、-24.5‰和-21.74‰,表明有机质主要来源于陆源.      

新街-恩格阿娄铁路工程建设的水土流失量预测

拟建的新街-恩格阿娄铁路穿过水土流失强度大的鄂尔多斯剥蚀丘陵区和毛乌素沙漠区,铁路建设的施工过程会增大沿线的水土流失量。本研究采用模式预测法对施工期内不同的施工单元和地类的水土流失量进行了估算。结果表明,工程建设区域内原地貌背景水土流失量为3.79×10^4t,在施工期间如果不采取任何防护措施,工程建设可能造成的水土流失量为7.47×10^4t,可能造成的新增水土流失量为3.69×10^4t,主体工程新增的水土流失量最大,达到2.4×10^4t,占可能新增的水土流失总量的65%左右,取土场次之,占28%左右,施工场地及营地新增的水土流失量最小,不到新增水土流失总量的1%。在水土流失防治上,重点防治区段是主体工程区、取土场和临时堆土区,本文对不同的施工单元提出了包括工程措施、植物措施和临时防护措施在内的水土流失防治对策。     

三江源区退化天然草地和人工草地生物量碳密度特征

生物量碳密度是生态系统表征碳截存能力的重要功能特征之一。为明晰三江源区高寒草地生物量碳密度特征,选取源区内3个县（玛沁县、甘德县、达日县）的退化天然草地（黑土滩）、退化人工草地、未退化天然草地为研究对象,通过野外调查取样和室内分析相结合的方法,对样区地上生物量、根系生物量及其碳密度进行测定与分析。结果表明：“黑土滩”地上生物量高于退化人工草地和天然草地;“黑土滩”活根和死根生物量都低于天然草地和退化人工草地。退化人工草地、“黑土滩”和天然草地的总生物量碳密度分别为719.47、706.57和2 233.09 g/m²。草地退化不仅改变了生态系统的生物量分配,而且改变了地上部分、活根和死根中的碳密度分配比例。退化人工草地和天然草地的活根和死根碳密度占总生物量碳密度的90%以上,“黑土滩”活根和死根碳密度占79.41%。活根碳密度与总生物量碳密度的比值在3种不同草地群落间的变化较地上植被和死根的大,因此,活根碳密度比例可以作为草地退化的敏感指标。