'Lysinibacillus saudimassiliensis' sp. nov., a new bacterial species isolated from air samples in the urban environment of Makkah, Saudi Arabia.

We report here the main characteristics of 'Lysinibacillus saudimassiliensis' strain 13S34_airτ (CSUR = P1222), a new species of the Lysinibacillus genus that was isolated from air samples in the city environment of Makkah, Saudi Arabia, during the pilgrim period of Hajj 2012.

As a part of a wider culturomics [1] and metagenomics study [2] in Saudi Arabia, we isolated a new bacterium, strain 13S34_airΤ, from two air samples in the urban environment of Makkah, Saudi Arabia, during the pilgrim period of Hajj 2012. For each air sample, a volume of 1 m3 was collected with a FCC-IV biological air sampler (AES Laboratories, Combourg, France) mounted with a nutrient agar plate containing the antifungal agent amphotericin (Majed Al-Buqami Co. BMC, Riyadh, Saudi Arabia) according to the manufacturer's instructions. No identification was obtained for the strain 13S34_airΤ using our systematic matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) screening on a MicroFlex spectrometer (Bruker Daltonics, Bremen, Germany). Strain 13S34_airΤ was cultured in 5% sheep's blood–enriched Columbia agar (bioMérieux, Marcy l'Etoile, France) for 2 days in an aerobic atmosphere at 37°C. Growth was observed only in aerobic conditions, and no growth occurred in anaerobic conditions. On Columbia agar, strain 13S34_airΤ colonies were opaque and round, with a greyish color, and their size varied between 4 to 6 mm in diameter. The strain 13S34_airΤ is a Gram-positive, obligate aerobic, endospore-forming, rod-shaped, catalase-positive and oxidase-negative bacterium. To test for spore formation, bacteria were heated at 80°C for 30 minutes and then were spread on blood-enriched Columbia agar. A positive result was taken after an overnight incubation at 37°C. Growth was observed in the range of 0.5 to 5% NaCl, with optimum growth at 0.5% NaCl. Observation under a light microscope showed bacterial motility.

The complete 16S rRNA gene was sequenced using fD1-rP2 primers as previously described and using a 3130-XL sequencer (Applied Biosciences, Saint Aubin, France) [3]. The strain 13S34_airΤ exhibited a 96.4% sequence similarity with Lysinibacillus sphaericus (NR115724), which was the phylogenetically closest species with standing in nomenclature (Fig. 1). Consequently, it putatively classifies the strain 13S34_airΤ as a new member of the genus Lysinibacillus within the family Bacillaceae in the phylum Firmicutes. The genus Lysinibacillus was first proposed in 2007 by Ahmed et al. [4] by the characterization of the type species Lysinibacillus boronitolerans and the transfer of Bacillus fusiformis to Lysinibacillus fusiformis comb. nov. and Bacillus sphaericus to Lysinibacillus sphaericus comb. nov. In 2012, an emended description of the genus Lysinibacillus was proposed by Jung et al. [5]. To date, the genus includes 21 species (http://www.bacterio.cict.fr/c/lysinibacillus.html); they are mostly environmental bacteria that are distributed primarily in soil [5].

Fig. 1

Phylogenetic tree highlighting position of ‘Lysinibacillus saudimassiliensis’ relative to other phylogenetically close members of Lysinibacillus genus. Numbers at nodes are percentages of bootstrap values obtained by repeating analysis 500 times to generate majority consensus tree. Only values >95% are displayed. Scale bar represents 0.5% nucleotide sequence divergence.

Strain 13S34_airΤ exhibited a 16S rRNA gene sequence divergence >1.3% with L. sphaericus, the closest related species with standing in nomenclature, which classifies it as a new representative of the Lysinibacillus genus isolated from air samples in the urban environment of Makkah. As a result, we propose the creation of ‘Lysinibacillus saudimassiliensis’ sp. nov., and the strain 13S34_air as the type strain.

MALDI-TOF MS spectrum

The MALDI-TOF MS spectrum of 13S34_airΤ is available online (http://www.mediterranee-infection.com/article.php?laref=256&titre=urms-database).

Nucleotide sequence accession number

The 16S rRNA gene sequence of the strain 13S34_airΤ was deposited in GenBank under accession number HG931343.1.

Deposit in a culture collection

Strain 13S34_airΤ was deposited in the Collection de Souches de l'Unité des Rickettsies (CSUR, WDCM 875) under number P1222.