Microbacterium memoriense sp. nov., a member of the Actinomycetota from marine beach sediment of the north coast of Portugal

Abstract

The oceans harbour a myriad of unknown micro-organisms that remain unstudied because of a failure to establish the right growth conditions under laboratory conditions. To overcome this limitation, an isolation effort inspired by the iChip was performed using marine sediments from Memória beach, Portugal. A novel strain, PMIC_1C1BT, was obtained and subjected to a polyphasic study. Cells of strain PMIC_1C1BT were Gram-positive, rod-shaped, divided by binary fission and formed colonies that were shiny light-yellow. Based on its full 16S rRNA gene sequence, strain PMIC_1C1BT was phylogenetically associated to the genus Microbacterium and its closest relatives were Microbacterium aurum KACC 15219T (98.55 %), Microbacterium diaminobutyricum RZ63T (98.48 %) and Microbacterium hatanonis JCM 14558T (98.13 %). Strain PMIC_1C1BT had a genome size of 2 761 607 bp with 67.71 mol% of G+C content and 2582 coding sequences, which is lower than the genus average. Strain PMIC_1C1BT grew from 15 to 30 °C, optimally at 25 °C, at pH 6.0 to 11.0, optimally between pH 6.0 and 8.0, and from 0 to 5 % (w/v) NaCl, optimally between 2.0 and 3.0 %. It grew with casamino acids, glutamine, methionine, N-acetylglucosamine, sodium nitrate, tryptophan, urea and valine as sole nitrogen sources, and arabinose and cellobiose as sole carbon sources. The major cellular fatty acids were anteiso-C15 : 0, iso-C16 : 0 and iso-C17 : 0. Genome mining revealed the presence of four biosynthetic gene clusters (BGCs) with low similarities to other known BCGs. Based on the polyphasic data, strain PMIC_1C1BT is proposed to represent a novel species, for which the name Microbacterium memoriense sp. nov. (=CECT 30366T=LMG 32350T) is proposed.