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Sourdough Bacteria Pump Out Mold Killers
听力内容：
60秒科学节目（SSS）是科学美国人网站的一套广播栏目，英文名称：Scientific American – 60 Second Science,节目内容以科学报道为主，节目仅一分钟的时间，主要对当今的科学技术新发展作以简明、通俗的介绍，对于科学的发展如何影响人们的生活环境、健康状况及科学技术，提供了大量简明易懂的阐释。
As many San Franciscans have noticed, sourdough bread stays fresher longer than the regular stuff. Sourdough’s extended freshness is due to extra fermentation that traps more moisture in the dough. But now we know that sourdough’s longevity is also because it can ward off mold. Because bacteria in some sourdough starters actually produce mold-killing compounds—essentially natural preservatives.
Most sourdough starters contain strains of Lactobacillus bacteria, like the poster childLactobacillus sanfranciscensis. Eight years ago, researchers isolated another strain calledLactobacillus hammesii from a French sourdough starter.
They’ve now discovered that the strain pumps out a potent antifungal as it digests bread flour. So they baked bread with the L. hammesii starter, sliced it, and waited. The loaf resisted mold for 12 days—a few days more than L. sanfranciscensis sourdough, and twice as long as typical bread. Those results are in the journal Applied and Environmental Microbiology. [Brenna A. Black et al., Antifungal hydroxy-fatty acids produced during sourdough fermentation: microbial and enzymatic pathways, and antifungal activity in bread]
L. hammesii isn’t the most common sourdough strain. But researchers say it could eliminate the need for added preservatives. Which would mean store-bought sourdough that’s additive-freeand lasts for weeks. Assuming you can wait that long to eat it.
—Christopher Intagliata
