#Microbiotiful - A handbag

Species of the mold Cladosporium grow best where it is damp, dark and warm, like in the human intestine. They are abundant throughout nature (except in the polar regions), and at least some level of Cladosporium is encountered in just about every household as whenever you open the window the spores get blown in. Not that this is necessarily a problem—Cladosporium are rarely pathogenic to humans. They are, however, significant allergens, and can affect people who suffer from asthma or respiratory diseases where they occur in great numbers.

Fusobacterium are tube-shaped, longish bacteria. Some potentially pathogenic species regularly feature in the mouth and nose of humans. As anaerobic bacteria they do not tolerate much oxygen, so they tend to subsist in low-oxygen pockets or within protective films of slime (biofilms) alongside other microbes to which they attach, hoping to make a breakthrough when conditions are ideal. This is the case when, for example, humans grow an abscess inside of which the fusobacteria can thrive.

You place your handbag on the kitchen furniture? Then maybe you should think again. Molds of the genus Aspergillus infest bread, fruit, vegetables, nuts—basically any food that contains a residual amount of water, making the food inedible for humans. Their filaments penetrate the infested food items and spoil them before you can see or taste that this has happened. As you have probably experienced, they are everywhere and grow best where it is damp and warm. Some may cause allergies or infections, and two species that infest pistachio nuts produce carcinogenic aflatoxins. 

In 1928 the microbiologist Alexander Fleming noticed that a Petri dish in which he was culturing bacteria was contaminated by a mold colony around which no bacteria had grown. The mold turned out to be Penicillium rubens, and what he observed were the effects of the world’s first antibiotic, penicillin. In nature, Penicillium are soil fungi that like cool and moderate climates, but have been isolated from all sorts of environments. They are probably present in the air and dust of your home, and possibly reside on your handbag. But they wouldn’t keep any nasty bacteria away there.

Rhodotorula yeasts are retrieved from diverse environments, from soil to surface waters to food. Spreading efficiently through the air, they can land anywhere, including on your handbag. Rhodotorula grow characteristic red to orange colonies with the smooth, wax-like appearance typical of yeasts. The colony color also distinguishes Rhodotorula from the generally more pathogenic Candida yeasts. The species R. glutinis is remarkably temperature-tolerant for a yeast. It can survive at over 60 °C for a while but also grow during refrigeration, occasionally causing spoilage of dairy products, fresh and processed meat, vegetables, and seafood.