Lysinibacillus fusiformis (commonly abbreviated L. fusiformis) is a gram-positive, rod-shaped bacterium of the genus Lysinibacillus. Scientists have yet to completely characterize this microbe’s pathogenic nature. Though little is known about this organism, several genome sequencing projects for various strains of L. fusiformis are currently underway.
Lysinibacillus fusiformis was initially isolated from the surface of beta vulgaris by German biologist Dr. O. Gottheil in 1901. Dr. Gottheil used a variety of isolation techniques, which included cultivating the organism on carrot and beet slices. L. fusiformis was originally known as Bacillus fusiformis prior to 2007; at which point it was reclassified to the genus Lysinibacillus, along with its close relative Bacillus sphaericus. The taxonomic classification of the organism was reassigned as a result of L. fusiformis’ distinctive characteristics, such as physiology, phylogeny, and peptidoglycan composition.
The meaning of “lysini,” as it pertains to members of the genus Lysinibacillus, signifies the presence of lysine, alanine, glutamic acid, and aspartic acid in the peptidoglycan layer of the cell wall. “Bacillus”, meaning small-rod, refers to the rod-shaped physiology of the bacterial form. “Fusum” translates to spindle and “forma” denotes a particular figure, appearance, or configuration. Thus, “fusiformis” is derived from the bacteria’s spindle-like structure.
Lysinibacillus fusiformis is a naturally occurring bacterium and various strains have been isolated from multiple environments including farming soil and factory wastewater. This organism is considered to be altogether mesophilic; growing best at a temperature range of 17-37 degrees Celsius. L. fusiformis is also considered to be mildly alkaliphilic and moderately halophilic; growing best at a pH range of 6-9.5 and an NaCl concentration of 2-7%.
In the 20th Century, Lysinibacillus fusiformis was believed to cause a form of pathogenicity in humans relating to tropical ulcer formations and dermal and/or respiratory infections. Some researchers believed that L. fusiformis infections could only occur as a symbiotic relationship with certain spirochaete species. Multiple experiments to prove the existence of pathogenicity have turned up inconclusive In 2010, researchers identified a strain of L. fusiformis, B-1, from 16S rRNA gene analysis. This strain has been found exclusively in the toxin of the puffer fish, Takifugu obscurus. This toxin is a tetrodotoxin, which is a highly fatal neurotoxin that destroys the central nervous system of humans causing paralysis. L. fusiformis is shown to be sensitive to the common broad-spectrum antibiotic known as tetracycline.
Lysinibacillus fusiformis tests positive for oxidase and is an obligate aerobe. This means that it can utilize oxygen to metabolize various sugars and other simple carbohydrates. However, it does not metabolize polysaccharides such as starch. This organism does not produce acid or gas from the metabolism of D-glucose or any other carbohydrates and does not reduce nitrate to nitrite. L. fusiformis can hydrolyze casein and gelatin. It can also utilize acetate, citrate, formate, lactate, and succinate as carbon sources. From a metabolic standpoint, L. fusiformis and Lysinibacillus sphaericus are nearly identical. As of now, the only known factor that distinguishes these two species is that L. fusiformis is positive for urease. This means that L. fusiformis can hydrolyze urea to produce ammonia and CO2. In 2011, the strain L. fusiformis ZC1 was shown to retain the ability to reduce chromate to chromium.
Applications to science and medicine:
In 2016, a group of researchers lead by Prof. A. B. Ade at the Department of Botany, Savitribai Phule University, Pune, MS, India reported 22% reduction in weight loss of the plastic (polythene) with Lysinibacillus fusiformis strain VASB14/WL after 2 months of regular shaking at room temperature.