No Such Thing As Islands

They say, “No man is an island”, but really, NOTHING is an island. An island isn’t even an island (Take that, They). You can’t go a day without interacting with another organism, whether you like it or not. I mean, I guess if you found a totally sterile room and killed all your body’s natural microbiota, but that’s cost-prohibitive and a little pointless. Even though there are plenty of harmful organism interactions, like petitioning and workplace pen-stealing, there are many beneficial interactions as well as a few…questionable ones.

Predation is one interaction that comes most readily to mind. One organism consumes another, to the predator’s advantage and the prey’s disadvantage. Another reason not to live in the crazy sterile room: you would also get hungry without so much as a plant organism to eat. Yes, herbivores do predate in a sense. But herbivory does not necessitate eating an entire organism; most just eat part. For instance, a cow will only eat the blades (leaves) of grass, not the roots. So the plant lives, battered and torn, but alive. Truly, cows are the cruelest of creatures.

Truly.

Similar to predation, parasitism involves one organism benefitting from the interaction to the other’s detriment. However in this instance, the parasite may not directly consume its host and definitely does not want to kill its host (at least not before it can reproduce). It’s like That One Housemate you had in college. They’re way too loud way too late at night, they eat your snacks and give away the endings to your video games, they ruin your shit and are always (ALWAYS) two days late with rent, but they do the dishes and keep the bathroom clean so you don’t kick them out even though they’re slowly draining your life away. You’ll crack in the middle of your Intro to Econ midterm, but by that time The Housemate will have moved on the a new host. Unlike an actual parasite, they will probably not have reproduced prior to this. Probably.

Check the basement.

 

(More interactions tomorrow)

 

Sources

Yancey, Paul. “Biotic Factors.” Marine Biology. Whitman College. Walla Walla, WA. 5 4 2011. Lecture.

Photo credit me.

My One, My Only, My Cheese

Today I’d like to tell you all about the love of my life, the one that will stay by my side through thick and thin, good times and bad: cheese. I could never go vegan because after a week of no cheese I’d snap like a cracker and eat until I choked. Or I’d shank somebody in the check-out line for their cheddar. Me and cheese are tight. So how is this relevant to biology? Well! Gather ‘round children and I shall tell you a story…

Consider cheesemaking as a process of “controlled spoilage” (Jenkins, 1996) of milk. Acids like vinegar or lemon juice are added to lower pH and digest the milk sugar, lactose, into lactic acid. However, bacteria of genus Streptococcus and Lactobacillus are used much more often. Rennet, an enzyme complex that causes casein (a milk protein) to clump, is then added to curd the milk. Rennet is derived from bacteria occurring in animal stomachs and, depending on the pickiness of the cheesemaker, may match the milk to the rennet (cow milk with calf rennet, goat milk with kid rennet, etc). However, this is not totally necessary or noticeable (outside flavor nuances) considering that vegetable rennet and genetically modified (GM) rennet are now readily available. Bacteria in vegetables produce a very similar enzyme complex to that in animals, while the GM rennet is derived from lab grown bacteria of the same type as those found in animal stomachs (GMOs aren’t so bad after all, eh?). Once the rennet has been added, the curdling milk is allowed to chill for a while at a set temperature (depending on the cheese, softer cheeses get lower temps and harder cheeses get higher temps).

Now for curding. Curding is whereby the cheese texture is established and involves draining the whey and cutting the curd (cheddaring). The more you cut it the denser the ultimate texture. Following is a process of cooking that fuses the cut curds. Blue cheese does not get cooked at this point and instead gets a dose of fungi of the Penicillium genus to give them their blue veins. Next the curd is salted, there are different methods, but the intention is to slow the bacteria down enough to allow for aging. Cheeses that aren’t aged long do not need as much salting as those that are, like those hard, wild, 9 month goudas that taste like whiskey and butterscotch. Mmmmmm…Ahem. Before aging, cheese will be further drained of whey and perhaps pressed into a mold. Soft cheeses like mozzarella and goat cheese do not get aged, but others, may sit for many months as the bacteria are allowed to continue digesting the milk proteins and fats. Temperature and treatment will vary to produce certain flavors. Brie are treated with Penicillium to give them a nice bloomy rind. I think the rinds taste like burning and gross, but they protect the cheese from bad bacteria and mold so I have learned to love the rind from a safe distance.

If you’ll excuse me, this all has gotten me hungry for some dense, bacterially spoiled milk and crackers.

Source

Fertman, Will. 2010. “Microbe Managing-The Lifesaving Potential of Cheese Bacteria”. Culture. 5 Feb 2013, <http://www.culturecheesemag.com/autumn_talk_microbes>

Jenkins, Steven. 1996. Cheese Primer. Workman Publishing Company, Inc., New York.

Photo credit me, calf credit the organic, raw milk dairy in Sequim I took it at.