Survey of Genomes - Clostridium perfringens

Being at the wrong place at the wrong time can sometimes mean trouble and that is exactly what happens when a particular soil bacterium gets into a wound. Ashley Redman from the 2019 Hiram College Genetics course spills the dirt on the leading cause of gas gangrene - Clostridium perfringens.

Welcome to Genetics Revolution. This is Ashley Redman from the 2019 Hiram College Genetics course hosting this episode of clostridium perfringens. Clostridium perfingens, CP for short, is a gram positive anaerobic, spore-forming, bacterium known to be the most widely distributed pathogen in nature. It is commonly found in soil, sewage, raw meat, and in the intestines of animals and humans as a member of the normal flora. The clostridium perfringens strains are classified into five groups, types A-E on the basis of their production of the four major toxins known as the alpha, beta, epsilon, and iota-toxins. Clostridium perfringens causes several human diseases, including food poisoning,  and gas gangrene. Clostridium perfringens (C. perfringens) is one of the most common causes of food poisoning in the United States. According to some estimates, this type of bacteria causes nearly a million illnesses each year.

During World War II, it was estimated that hundreds of thousands of soldiers died of gas gangrene as a result of battlefield injuries, and clostridium perfringens was widely recognized as being the most important casual organism of the disease. After the cells or spores entered into the body through injury, the organism grows rapidly in the host tissue, producing various toxins and enzymes that case massive destruction of the host tissues. The infection often lead to systematic toxemia, shock, and death unless promoted antibiotic and surgical treatment was given.

The  complete genome of c. Perfringes contains a 3,031,430-bp sequence that comprises 2,660 protein coding regions. The genome includes a 3.53 Mb chromosome, respectively, the genome  includes  five circular plasmids. C. perfringens chromosome sequences identified to be around  ~247 kb.

One key finding from the genome sequence, was that the genome contains typical anaerobic fermentation enzymes leading to gas production but no enzymes for the tricarboxylic acid cycle or respiratory chain. Various saccharolytic enzymes were found, but many enzymes for amino acid biosynthesis were lacking in the genome. Twenty genes were newly identified as putative virulence factors of C. perfrin- gens, and we found a total of five hyaluronidase genes that will also contribute to virulence. The genome analysis also proved an efficient method for finding four members of the two-component regulon. 

Another study used the complete genome of Clostridium perfringens to identify   numerous toxins produced, which are responsible for severe diseases in man and animals.  For example, delta toxin was characterized to be cytotoxic for cells expressing the ganglioside GM2 in their membrane. The study reported the genetic characterization of Delta toxin. Delta toxin consists of 318 amino acids, its 28 N- terminal amino acids corresponding to a signal peptide. The secreted Delta toxin (290 amino acids; 32619 Da) is a basic protein (pI 9.1) which shows a significant homology with C. perfringens Beta toxin (43% identity), alpha toxin and leukotoxins.
 
Lastly, another study investigated the virulence associated genome content and the genetic relationship among clostridium perfingens isolated from healthy and necrotic enteritis infected chickens and turkeys, applying genome sequencing. The pathogens associated with necrotic enteritis in chickens has not been examined in diseased turkeys. Strains expressing the NetB toxin are the main cause of necrotic enteritis in chickens and has a remarkable imact on animal welfare and the production economy in the international poultry industry. Whole genome sequencing of clostridium perfingens stain A was used to determine that the pathogenesis of necrotic enteritis in turkeys appears to be different fron that of broiler chickens. 

It is important to understand the mechanism of this bacterium because it is the most common cause of food borne illness. By using genome sequencing, researchers have been able to understand the mechanism of clostridium perfingens and genetically study how it infects humans and animals. This knowledge can then be applied to create ways to make sure humans do not contract this food borne illness. Another benefit from the geneome sequencing and understanding clostridium perfingens, it can keep soldiers healthier on the battle field, which strengthens a military force. If soilders contract gangrene we can create an effective treatment for the potently deadly illness. 
Who knew such a small organism could cause gangrene and be the primary cause of food borne illness. Thanks for listening. 

References:
Ronco, Troels, et al. “Genome Analysis of Clostridium Perfringens Isolates from Healthy and Necrotic Enteritis Infected Chickens and Turkeys.” BMC Research Notes, vol. 10, July 2017, pp. 1–6. EBSCOhost, doi:10.1186/s13104-017-2594-9.

Awad, Milena M., et al. “Functional Analysis of an FeoB Mutant in Clostridium Perfringens Strain 13.” Anaerobe, vol. 41, Oct. 2016, pp. 10–17. EBSCOhost, doi:10.1016/j.anaerobe.2016.05.005.

Manich, Maria, et al. “Clostridium Perfringens Delta Toxin Is Sequence Related to Beta Toxin, NetB, and Staphylococcus Pore-Forming Toxins, but Shows Functional Differences.” PLoS ONE, vol. 3, no. 11, Nov. 2008, pp. 1–13. EBSCOhost, doi:10.1371/journal.pone.0003764.

Mehdizadeh Gohari, Iman, et al. “Plasmid Characterization and Chromosome Analysis of Two NetF+ Clostridium Perfringens Isolates Associated with Foal and Canine Necrotizing Enteritis.” PLoS ONE, vol. 11, no. 2, Feb. 2016, pp. 1–20. EBSCOhost, doi:10.1371/journal.pone.0148344. 

Shimizu, Tohru, et al. “Complete Genome Sequence of Clostridium Perfringens, an Anaerobic Flesh-Eater.” Proceedings of the National Academy of Sciences of the United States of America, vol. 99, no. 2, Jan. 2002, p. 996. EBSCOhost, doi:10.1073/pnas.022493799.  

FoodSafety.gov. “Clostridium Perfringens.” FoodSafety.gov, U.S. Department of Health and Human Services, 27 Oct. 2009, www.foodsafety.gov/poisoning/causes/bacteriaviruses/cperfringens/index.html.