武汉城市圈“生物迁移-区域降温”复合功能生态网络构建

【目的】生态网络是大尺度景观保护的有效空间途径,既有研究所构建的生态网络多侧重于生物多样性保护,对更多潜在的效益考虑不足,因此亟须拓展生态网络的更多功能。【方法】以武汉城市圈为例,综合地表温度反演、形态学空间格局分析、景观连通性分析和电路理论等方法,协同构建生物迁移网络与区域降温网络,并叠合生成复合功能生态网络格局,将识别出的双网络交点、夹点和障碍点作为生态保护与修复的重点区域。【结果】1)研究区共有生物多样性源地22个、区域降温源地27个,二者主要分布于研究区东北部和南部;2)识别出生物迁移廊道44条（重要廊道21条）、区域降温廊道51条（重要廊道29条）;3)叠加分析发现共有8个源地斑块承担复合功能;4)复合功能视角下的生态保护与修复重点区域包含双网络交点7处,生物迁移网络夹点面积85.4 km²、障碍点面积724.9 km²,区域降温网络夹点面积50.1 km²、障碍点面积926.6 km²。【结论】双网络耦合形成复合功能生态网络,协同增益效果体现为网络功能拓展与结构韧性提升。武汉城市圈应从现有源地保护与潜在源地培育、双网络障碍点修复、双网络夹点与交点保护3个方面进行系统性、全局性的生态保护和修复工作。     

Strains of the Lactobacillus casei group show diverse abilities for the production of flavor compounds in 2 model systems

Cheese flavor development is directly connected to the metabolic activity of microorganisms used during its manufacture, and the selection of metabolically diverse strains represents a potential tool for the production of cheese with novel and distinct flavor characteristics. Strains of Lactobacillus have been proven to promote the development of important cheese flavor compounds. As cheese production and ripening are long-lasting and expensive, model systems have been developed with the purpose of rapidly screening lactic acid bacteria for their flavor potential. The biodiversity of 10 strains of the Lactobacillus casei group was evaluated in 2 model systems and their volatile profiles were determined by gas chromatography-mass spectrometry. In model system 1, which represented a mixture of free AA, inoculated cells did not grow. In total, 66 compounds considered as flavor contributors were successfully identified, most of which were aldehydes, acids, and alcohols produced via AA metabolism by selected strains. Three strains (DPC2071, DPC3990, and DPC4206) had the most diverse metabolic capacities in model system 1. In model system 2, which was based on processed cheese curd, inoculated cells increased in numbers over incubation time. A total of 47 compounds were identified, and they originated not only from proteolysis, but also from glycolytic and lipolytic processes. Tested strains produced ketones, acids, and esters. Although strains produced different abundances of volatiles, diversity was less evident in model system 2, and only one strain (DPC4206) was distinguished from the others. Strains identified as the most dissimilar in both of the model systems could be more useful for cheese flavor diversification.     

Biodiversity and safety aspects of yeast strains characterized from vineyards and spontaneous fermentations in the Apulia Region,Italy

This work is the first large-scale study on vineyard-associated yeast strains from Apulia (Southern Italy). Yeasts were identified by Internal Transcribed Spacer (ITS) ribotyping and bioinformatic analysis. The polymorphism of interdelta elements was used to differentiate Saccharomyces cerevisiae strains. Twenty different species belonging to 9 genera were identified. Predominant on the grape surface were Metschnikowia pulcherrima, Hanseniaspora uvarum and Aureobasidium pullulans, whereas M. pulcherrima and H. uvarum were dominant in the early fermentation stage. A total of 692 S. cerevisiae isolates were identified and a number of S. cerevisiae strains, ranging from 26 to 55, was detected in each of the eight fermentations. The strains were tested for biogenic amines (BAs) production, either in synthetic media or grape must. Two Pichia manshurica, an Issatchenkia terricola and a M. pulcherrima strains were able to produce histamine and cadaverine, during must fermentation. The production of BAs in wine must was different than that observed in the synthetic medium. This feature indicate the importance of an “in grape must” assessment of BAs producing yeast. Overall, our results suggest the importance of microbiological control during wine-making to reduce the potential health risk for consumer represented by these spoilage yeasts.     

天津潮间带大型底栖动物特征

2006年10月4日-10月7日对天津蛏头沽、驴驹河以及高沙岭潮间带进行了大型底栖动物调查。调查结果表明,该区共有5大类底栖动物30种,其中软体动物最多,平均栖息密度为264 ind./m2,平均生物量为114.84 g/m2,蛏头沽潮间带的栖息密度和生物量是三个区域中最低的。北塘河口至蛏头沽潮间带香农-威纳多样性指数平均值为0.28,属于重污染区;临港工业区至独流碱河潮间带香农-威纳多样性指数平均值为1.67,属于中度污染区,并且历史上存在的毛蚶、缢蛏等经济贝类已很少见到。此次调查发现大量泥螺。