Amphibacillus xylanus

Classification

• Kingdom - Bacteria
• Phylum - Firmicutes
• Class - Bacilli
• Order - Bacillales
• Family - Bacillaceae
• Genus - Amphibacillus

Species

NCBI: Taxonomy

Amphibacillus xylanus

Description and Significance

Amphibacillus xylanus is a Gram positive, spore-forming, and chemoorganotrophic bacterium that was isolated from composts of manure with grass and rice straw. They are also facultative anaerobic organism that can grow in several different environments. However, it lacks cytochrome, quinone, and catalase. This helps explain the method of metabolism that Amphibacillus xylanus relies on.

Amphibacillus xylanus is also flagellated and motile, and it maintains many of the characteristics known to Amphibacillus. For example, the cells are rod-shaped and are 0.3 to 0.5 micrometers in diameter and are 0.9 to 1.9 micrometers long. The spores are oval in shape and heat resistant. The sporangia where the spores are formed are lysed and the spores are then released. These spores are formed under both aerobic and anaerobic conditions. Amphibacillus xylanus does not grow in nutrient broth, but it produces ethanol, acetic acid, and formic acid under anaerobic conditions and acetic acid under aerobic conditions from glucose. When colonies are grown on glucose agar, the colonies are small, circular, smooth, convex, entire, and white after only one day of incubation.

The microorganism grows ideally at pH values between 8 and 10, but it cannot grow at pH 7. The bacterium also contains a considerable amount of saturated straight-chain fatty acids, and little of its genome matched the genome of other bacterium.

Genome Structure

It has been found that Amphibacillus xylanus is not related to representative species of the genera bacillus, which include clostridium and sporolactobacillus. In fact, little of its genome has matched any other bacterium.

Metabolism and Life Cycle

One of the bioenergetics properties of Amphibacillus xylanus is the fact that the flavoprotein NADH oxidase from Amphibacillus xylanus consumes oxygen to produce hydrogen peroxide. Furthermore, it is believed that NADH is in control of the intracellular redox balance of the cell under aerobic conditions. Despite the fact that Amphibacillus xylanus lacks a respiratory system and hemeproteins, catalase, and peroxidase, it is still able to grow efficiently and it has the same growth rate under both anaerobic and aerobic conditions. It is able to do so because it has aerobic and anaerobic pathways that produce similar amounts of ATP.

Ecology and Pathogenesis

Amphibacillus xylanus is a chemoorganotroph and can be found in both anaerobic and aerobic conditions because it is a facultative anaerobic organism. And while it was isolated from alkaline compost, it can also be found in several different environments. These bacterium can survive in temperatures from 25° C to 45° C, however, it cannot grow at 50° C.

References

Niimura, Y., Koh, E., Yanagida, F., Suzuki, K., Komagata, K., and Kozaki, M. "Amphibacillus xylanus" gen. nov., sp. nov., a Facultatively Anaerobic Sporeforming Xylan-Digesting Bacterium Which Lacks Cytochrome, Quinone, and Catalase". "International Journal of Systematic and Evolutionary Microbiology". 1990. Volume 40. p. 297-301.

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Author

Page authored by Lauren Jackson and Hillary Albert, students of Dr. N. Walker at Michigan State University.