{"id":142,"date":"2008-05-30T18:25:09","date_gmt":"2008-05-31T01:25:09","guid":{"rendered":"http:\/\/www.bigroom.org\/wordpress\/?p=142"},"modified":"2008-05-30T18:25:09","modified_gmt":"2008-05-31T01:25:09","slug":"a-small-modification-of-kochs-plating-method","status":"publish","type":"post","link":"http:\/\/www.bigroom.org\/wordpress\/?p=142","title":{"rendered":"“A small modification of Koch’s plating method.”"},"content":{"rendered":"

Only two more days for the Classic Papers Challenge<\/a>, so if I’m going to get any more up, I’d better get my butt in gear.<\/p>\n

Here’s a nice easy one:<\/p>\n

Petri, R. J.:”Eine kleine Modification des Koch?schen Plattenverfahrens.” Centralblatt f?r Bacteriologie und Parasitenkunde; 1887; Vol. 1, pages 279-280.<\/div>\n

The American Society for Microbiology has a translation<\/a> available online. It’s only about a page-and-a-half of relatively large type – check it out.<\/p>\n

There’s a trick we microbiologists use for growing bacteria. You make a solid (but wet) surface that contains whatever nutrients the microbe (bacteria, archaea, yeasts, mold spores…) you’re interested in need, and then you spread a diluted mixture of the microbe on it. The idea is that since the surface is solid the microbes can’t move around too much, and at any spot where a single cell starts initially, a whole pile of that cell and it’s genetically-identical (non-sexually-produced) clone-children will form until it gets big enough to see without a microscope. This cell-pile is called a “colony”, and you can poke or rub it with a sterile object, then stick the object into a sterile nutrient source. The end result is you have a “pure” culture of microbes that are effectively genetically identical. The solid material could be a lot of things – I’ve seen references to using slices of potato – though these days agar-agar<\/a> gel mixed with nutrients is the preferred substance.<\/p>\n

Koch (that is, Robert Koch of “Koch’s Postulates<\/a>” fame, not Ed Koch the former mayor of New York City) used gelatin (so, hey, here’s another thing you can do with your expired Jell-O&reg;). He apparently used to have a stack of shallow bowls, and had to use a special pouring device to carefully dump the gelatin into each stacked bowl in turn, then cover the works with a bell jar in order to keep stuff from falling into them from the air and contaminating them.<\/p>\n

This was kind of a pain to work with, so some clever guy named Julius came up with a modification of this method in 1887, using pairs of shallow dishes, one slightly larger than the other so that it could be turned upside down to use as a lid. Then, you don’t necessarily need the bell jar, and you don’t need to stack them so they’re easier to pour.<\/p>\n

\"\"Julius Robert Petri’s idea was so useful that we still use it today. Oh, yeah, and they named the dish-and-lid combination<\/a> after him.<\/p>\n

How’s that for a “classic” paper?<\/p>\n

Meanwhile, my “Mountain Dew? Wine<\/a>” project is turning out to be substantially more educational and fascinating than I’d hoped. There seems to be a decent amount of information available on how benzoic acid affects yeasts. I intend to turn that into a post later, but first I’ll try to find at least one more old paper to post before tomorrow is over…<\/p>\n","protected":false},"excerpt":{"rendered":"

Only two more days for the Classic Papers Challenge, so if I’m going to get any more up, I’d better get my butt in gear. Here’s a nice easy one: Petri, R. J.:”Eine kleine Modification des Koch?schen Plattenverfahrens.” Centralblatt f?r Bacteriologie und Parasitenkunde; 1887; Vol. 1, pages 279-280. The American Society for Microbiology has a … Continue reading “A small modification of Koch’s plating method.”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[48,28,9,22,13,12,15,6,16,23,8],"tags":[67,167,44,179,180,566,86,168,178,166,88,572,177,69,61],"class_list":["post-142","post","type-post","status-publish","format-standard","hentry","category-brew","category-expired-jello","category-food-science","category-freakish-eukaryotes","category-me-me-me","category-meta-blogging","category-methods","category-microbiology","category-science-history","category-what-i-learned-in-school-today","category-why-does-it-work","tag-bacteria","tag-benzoic-acid","tag-brewing","tag-koch","tag-laboratory-apparatus","tag-microbiology","tag-mold","tag-mountain-dew","tag-petri","tag-preservatives","tag-science","tag-science-history","tag-scientific-papers","tag-wine","tag-yeast"],"_links":{"self":[{"href":"http:\/\/www.bigroom.org\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/142","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.bigroom.org\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.bigroom.org\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.bigroom.org\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.bigroom.org\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=142"}],"version-history":[{"count":0,"href":"http:\/\/www.bigroom.org\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/142\/revisions"}],"wp:attachment":[{"href":"http:\/\/www.bigroom.org\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=142"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.bigroom.org\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=142"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.bigroom.org\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=142"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}