Bacillus safensis is a gram-positive, spore-forming, and rod bacterium, originally isolated from a spacecraft in Florida and California. B. safensis could have possibly been transported to the planet Mars on spacecraft Opportunity and Spirit in 2004.

Discovery and importance

Thirteen strains of the novel bacterium Bacillus safensis were first isolated from spacecraft surfaces and assembly-facility surfaces at the Kennedy Space Center in Florida as well as the Jet Propulsion Laboratory in California. The bacterium gets its name from the JPL Spacecraft Assembly Facility (SAF).

V.V. Kothari and his colleagues from Saurashtra University in Gujarat, India, first isolated another strain, B. safensis VK. Strain VK was collected from Cuminum cyminum, a cumin plant in the desert area of Gujarat, India. Specifically, the bacteria were collected from the rhizosphere of the cumin plant.

Ram S. Singh and colleagues discovered one of the strains, AS-08, in soil samples of root tubers of asparagus plants in a botanical garden at Punjabi University in India. B. safensis AS-08 was found to have inulase activity, which is used for the production of fructooligosaccharides and high-fructose corn syrup. Fructooligosaccharides are used as artificial sweeteners and can be found in many commercial food products. Corn syrup is also found in many processed foods.

Davender Kumar and colleagues from Kurukshetra University in India isolated strain DVL-43 from soil samples. This strain was found to possess lipase, which is an important enzyme for fat digestion. Lipases are a class of chemicals that are abundant in nature amongst plants, animals and microorganisms that are widely used in industry for production of food, paper products, detergents and biodiesel fuel.

P. Ravikumar of the Government Arts College at Bharathiar University in India isolated strain PR-2 from explosive-laden soil samples. This strain was identified by its 16S rDNA sequence by Sanger dideoxy sequencing method and deposited in the GenBank in Maryland, U.S. It carries the accession number KP261381 with 885 base pairs of linear DNA and the base count 175 a 295 c 199 g 216 t.

Physical characteristics and metabolism

Bacillus safensis is a gram-positive, spore-forming rod bacterium. B. safensis is also an aerobic chemoheterotroph. Cell size ranges from 0.5 to 0.7 μm in diameter and 1.0–1.2 μm in length. B. safensis FO-036b has an optimal temperature range of , and cannot grow at .

Strain VK of B. safensis is a salt-tolerant microorganism, and can grow beyond the 0–10% salt range of the general microbial species. The genome also displays 73 tRNA genes.

Strains

Listed below are currently identified Bacillus safensis strains, including where they were discovered, and the year discovered (if available).

  • Bacillus safensis subsp. safensis FO-36B – clean room – California (1999)
  • Bacillus safensis NH21E_2 – sediment – South China Sea
  • Bacillus safensis B204-B1-5 – sediment – South China Sea
  • Bacillus safensis EMJ-O3-B1-22 – sediment – South China Sea
  • Bacillus safensis CJWT7 – sediment – South China Sea
  • Bacillus safensis SLN29 – sediment – South China Sea
  • Bacillus safensis BMO4-13 – surface water – Pacific Ocean
  • Bacillus safensis D21 – sediment – Arctic Ocean
  • Bacillus safensis HYg-9 – intestinal tract contents of fish – Xiamen Island
  • Bacillus safensis NP-4 – surface water – Arctic Ocean
  • Bacillus safensis 15-BO4 10-15-3 – Sediment – Bering Sea
  • Bacillus safensis DW3-7 – aquaculture water – shrimp farm
  • Bacillus safensis FO-33 – clean room – California (1999)
  • Bacillus safensis SAFN-001 – entrance floor of Jet Propulsion Lab (2001)
  • Bacillus safensis SAFN-027 – ante room of Jet Propulsion Lab (2001)
  • Bacillus safensis SAFN-036 – clean room of Jet Propulsion Lab (2001)
  • Bacillus safensis SAFN-037 – clean room floor of JPL (2001)
  • Bacillus safensis KL-052 – clean room cabinet top of JPL (2001)
  • Bacillus safensis 51-3C – Mars Odyssey spacecraft surface (2002)
  • Bacillus safensis 81-4C – Mars Odyssey assembly facility floor (2002)
  • Bacillus safensis A2-2C – Mars Odyssey assembly facility floor (2002)
  • Bacillus safensis 84-1C – Mars Odyssey assembly facility floor (2002)
  • Bacillus safensis 84-3C – Mars Odyssey assembly facility floor (2002)
  • Bacillus safensis 84-4C – Mars Odyssey assembly facility floor (2002)
  • Bacillus safensis JPL-MERTA-8-2 - Mars Exploration Rover clean room of JPL (2004)
  • Bacillus safensis DVL-43 – India
  • Bacillus safensis MAE 17 - soil - Egypt (2019)
  • Bacillus safensis subsp. osmophilus BC09 - condensed milk - Spain (2019)

Several isolates of the genus Bacillus are nearly identical to Bacillus pumilus. The group of isolates related to B. pumilus contains five related species: B. pumilus, B. safensis, B. stratosphericus, B. altitudinis, and B. aerophilus. These species are difficult to distinguish due to their 99.5% similarity in their 16S rRNA gene sequence. Recently, scientists have discovered an alternate way to differentiate between these closely related species, especially B. pumilus and B. safensis.