Sounds like a fun project! Will your class be investigating the ability of Acinetobacter calcoaceticus (aka RAG-1) to disperse crude oil in water?

You may know that RAG-1 is an isolate of a species of marine bacteria in the genus Acinetobacter. The name Acinetobacter comes from Greek words for non-moving and rod. RAG-1 was first described in 1972 in a report by Abraham Reisfeld, Eugene Rosenberg and David Gutnick in the journal Applied Microbiology. Since that initial report, it was discovered that RAG-1 secretes a lipopolysaccharide (long-chain sugar and fat molecule) called emulsan. When the bacteria are growing without another source of carbon, they will secrete more emulsan, which will emulsify oil/breakdown hydrocarbons. The bacteria can then use the carbon from the dispersed/broken down oil as a nutrient source. To do this, the bacteria need nitrogen and phosphorous.

But what about the human health factor of this bacteria?

Acinetobacter calcoaceticus is widely distributed in nature and is commonly living in and on mammals, including humans, and rarely causes any kind of infection. In fact, the team on Discovery Channels MythBusters show found hundreds of Acinetobacter colonies on a household kitchen sponge! It is considered a microbe that can be treated with Biohazard Level 1 precautions: this category includes microbes such as chicken pox and E. coli. At this level, usually the precautions are minimal, usually using latex gloves, and perhaps some kind of facial protection to avoid breathing in the microbes. Decontamination procedures at this level include hand-washing with anti-bacterial soap, washing down possible contaminated surfaces with disinfectants, etc. In a lab, waste materials from this biohazard level would be autoclaved before going to the dump. In a classroom setting, waste materials could be soaked in a 1:5 chlorine bleach solution for at least 20 minutes before being disposed of if an autoclave is not available.

The trouble you might hear regarding Acinetobacter is mostly in regards to the other closely related species. Infection with A. calcoaceticus is very rare, and really only occurs in people with compromised immune systems. (Something to keep in mind if any students are on immunosuppressants, or will come in immediate contact with the elderly, infants or anyone with HIV/AIDS, etc.) However, a closely related species, A. baumannii, causes most of the human Acinetobacter infections. A. baumannii can cause various infections, including pneumonia, wound infections, and meningitis. Again, most of these infections occur in immuno compromised people and rarely outside of intensive care units and other health care settings. A. calcoaceticus and A. baumannii are so closely related that most standard laboratory tests cannot tell the difference between them, which leads many hospitals to lump the treatment of the two species together. What makes Acinetobacter infections troubling is that Acinetobacter is naturally resistance to many antibiotics, and an increase in multi-drug resistant A. baumannii strains has been reported. However, there are proven ways to treat Acinetobacter infections, and proper disinfection and protocol in hospitals greatly reduces cases of Acinetobacter infection. As of 1999, The National Institutes of Health classified even A. baumannii as a Risk Group 2 (RG2) Agent: RG2 agents are associated with human disease which is rarely serious and for which preventive or therapeutic interventions are often available.

So, the bottom line is: if your class is to work with Acinetobacter calcoaceticus (and it is definitely Acinetobacter calcoaceticus, not another species!), if careful techniques are used to disinfect waste and surfaces, and gloves (and perhaps surgical masks) are used, and immuno compromised people are excluded from participating, then everything should go fine! Best of luck with your experiments!

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