Rhodoplanes azumiensis

Rhodoplanes azumiensis is a thermotolerant Proteobacteria isolated from sediment mud and cyanobacterial mats located in , located in the Azumi district, Matsumoto, Nagano Prefecture, Japan. R. azumiensis is a photoheterotroph that is capable of using many organic materials as its carbon source. Colonies and liquid cultures exhibit a brownish red color when grown phototrophically, and are colorless when grown aerobically in darkness.^[1]

Isolation[]

Samples were taken from sediment mud and cyanobacterial mats located in Nakanoyu hot springs in Japan. The samples were then introduced to 20 mL screw-capped test tubes containing 10-mL of Rhodoplanes (RPL) medium and were incubated at 42°C. Pink cultures occurred and were plated on RPL agar plates and incubated aerobically at 42°C. Isolation streaking was conducted multiple times until 2 novel species were isolated.

DNA sequencing and confirmation of novelty[]

20 strains of Rhodoplanes were isolated in the method outlined above, of those, 18 had 100% similarity levels of 16S rRNA to previously outlined and published 16S rRNA Rhodoplanes species. The two novel species isolated demonstrated a 96.9-98.7% similarity to previously isolated Rhodoplanes species. DNA-DNA hybridization was then conducted to determine whether or not these two isolated species were novel. Rhodoplanes azumiensis hybridized between 48 and 52% with previously isolated Rhodoplanes species allowing the researchers to determine it was indeed a novel strain.

Characteristics[]

R. azumiensis are gram-negative rods 1 μm wide and 2-4 μm long. They are capable of motility by a singular polar flagella. R. azumiensis uses budding to multiply, and form rosette-like clusters in older cultures. Colonies and liquid cultures are brownish red when grown phototrophically and colorless when grown aerobically in darkness. Their major carotenoid components are rhodopin, , , , and lycopene allowing them to utilize absorption maxima at 376, 498, 529, 594, 800, 859 and 892 nm. R. azumiensis 16S rRNA GC content is 70.4%. The optimal growth is 40° C, the optimum pH is between 6.8 and 7.2, and they are able to use pyruvate, citrate, malate, acetate, lactate, succinate, fumarate, and malonate as carbon sources.

References[]