Macromonas bipunctata
Macromonas bipunctata is a Gram-negative, colorless, and heterotrophic sulfur bacterium of the genus Macromonas. It is commonly found in sewage aeration tanks and caves where moonmilk has formed. In the 1920s, researcher Gicklhorn first discovered this organism under the name Pseudomonas bipunctata. After further study and culturing by Utermöhl and Koppe, in 1923, it was later renamed Macromonas bipunctata. This organism is thought to be non-pathogenic species. In fact, the moonmilk produced was referenced as a remedy for infections in the Middle Ages. Background History In the Middle Ages, "moonmilk" was used as a medicine. People often used it to cure infections and accelerate the healing process. Moonmilk is more than simply Macromonas bipunctata. It also contains populations of cyanobacteria, fungi, green algae, and actinomycetes, which are the main producers of antibiotics. This could explain why it was effective as a potential agent for healing. Etymology M. bipunctata was first isolated by Gicklhorn in the slime of a large basin Gratz in a botanical garden in 1924. Gicklhorn treated this species as a colorless sulfur bacteria and called it Pseudomonas bipunctata. The Greek root "monad/monas" was commonly used for microbiology to indicate a unicellular or single unit organism(s)/bacterium in the 1920s. Furthermore, bipunctata can be separated into the Latin roots "bi", meaning two, and "punctata" , meaning spotted, as seen in cultured M. bipunctata. Years later, Dubinina, Grabovich, and La Rivière isolated this species from the precipitates of sewage aeration tanks called the white mat. Upon more research of this organism, it was renamed Macromonas bipunctata. "Macro" is the Greek term for large, as the cell itself is on average larger than most bacteria. Additionally, this species can also be found in many caves where moonmilk is present. Microbiology Macromonas bipunctata is a Gram-negative, aerobic, irregular/pear shaped, heterotrophic sulfur bacterium. M. bipunctata has a very large cell area at 9 µm x 20 µm . Its motility consists of flagella 20–40 µm long that moves around using a structural beam of polar flagella located at one end of its body. Phylogeny and taxonomy The closest species to Macromonas bipunctata within the class Betaproteobacteria are Malikia granosa and Malikia spinosa based on 16S rRNA gene as shown in many previous studies. Malikia nests within the family Comamonadaceae in the phylum Pseudomonadota and is also aerobic. Malikia granosa has a 96.5% similarity to M. bipunctata, whereas Hydrogenophaga flava has a 95.61% similarity in its 16S rRNA gene. Culturing Most of the culturing procedures model Dubinina and Grabovich's 1984 article on M. bipunctata: it includes sodium acetate (1 g/L), calcium chloride (0.1 g/L), casein hydrolysate (0.1g/L), yeast extract (0.1g/L), and agar (1g/L) along with a vitamin supplement, trace elements, and FeS as a sulfide source. M. bipunctata was cultured on an agar plate for 2–3 days at 28 °C (mesophile as optimum for cultivation set at around 28 degrees) before several species of Macromonas bipunctata appeared. The optimal pH level for growing is around 7.2–7.4. The colonies that form produce a white film