细菌-雪花的核心

Those beautiful snowflakes drifting out of the sky may have a surprise inside -- bacteria.

Atmospheric scientists have long known that under most conditions moisture needs something to cling to in order to condense into snow and rain. A study published Friday in the journal Science shows a large share of those so-called nucleators turn out to be bacteria that can affect plants.

"Bacteria are by far the most active ice nuclei in nature," said Brent C. Christner, an assistant professor of biological sciences atLouisianaStateUniversity.

Christner and colleagues sampled snow from Antarctica,France,MontanaandCanada'sYukonand found that as much as 85% of the nuclei were bacteria, he said. The bacteria finding was most common inFrance, followed byMontanaand theYukon, and was even present inAntarctica.

The most common bacteria found were Pseudomonas syringae, which can cause disease in several types of plants including tomatoes and beans.

In the past, scientists have tried to eliminate Pseudomonas, Christner said, but now that it turns out to be a major factor in encouraging snow and rain, he wonders if that is a good idea. Eliminating the bacteria might result in less rain or snow, or it might be replaced by other nuclei such as soot and dust.

一项研究惊奇地发现，天空飘洒的美丽雪花，里面的核心竟是细菌。

大气科学家早就知道，在大多数情况下，大气中的湿气需要附着在某些物质上才能凝结成雨雪。《科学》杂志周五发表的一项研究表明，作为雨雪凝结核的所谓“冰核”很大一部分是细菌，这种细菌会使植物产生病变。
乐学网收集整理

美国路易斯安那州立大学的一名生物学家助教Brent C. Christner说：“细菌是目前自然界最活跃的冰核”。

Christner还说，他和同事从南极洲、法国、美国的蒙大纳和加拿大的育空不同地区采集的雪样本中，85%的凝结核是细菌。含细菌最多的雪花是法国，其次是蒙大纳和育空，连南极洲的雪花也有少量的细菌。

雪花中最常见的的细菌是丁香假单胞菌，它能使多种植物致病，如番茄、豆子。

Christner称，过去科学家试图消除假单胞菌，但是现在看来，这不是一个好主意，因为证据证明这种细菌在制造雨雪的过程中起着重要作用。消除细菌可能会导致雨雪的减少，可以由其它凝结核如煤烟和尘埃代替细菌解决这一问题。