A substantial majority of global population owns cellular phones independently to demographic factors like age, economic status, and educational attainment. In this study, we investigated the diversity of microorganisms associated with cellular phones of 27 individuals using cultivation-based methods. Cellular phones were sampled using cotton swabs and a total of 554 isolates representing different morphotypes were obtained on four growth media. Matrix-assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry could generate protein profiles for 527 isolates and species-level identification was obtained for 415 isolates. A dendrogram was constructed based on the protein profiles of the remaining isolates, to group 112 isolates under 39 different proteotypes. The representative strains of each group were selected for 16S rRNA gene and ITS region sequencing based identification. Staphylococcus, Bacillus, Micrococcus, and Pseudomonas were the most frequently encountered bacteria, and Candida, Aspergillus, Aureobasidium, and Cryptococcus were in case of fungi. At species-level the prevalence of Micrococcus luteus, Staphylococcus hominis, Staphylococcus epidermidis, Staphylococcus arlettae, Bacillus subtilis, and Candida parapsilosis was observed, most of these species are commensal microorganisms of human skin. UPGMA dendrogram and PCoA biplot generated based on the microbial communities associated with all cellular phones exhibited build-up of specific communities on cellular phones and the prevalence of objectionable microorganisms in some of the cellular phones can be attributed to the poor hygiene and sanitary practices. The study also revealed the impact of MALDI-TOF MS spectral quality on the identification results. Overall MALDI-TOF appears a powerful tool for routine microbial identification and de-replication of microorganisms. Quality filtering of MALDI-TOF MS spectrum, development of better sample processing methods and enriching the spectral database will improve the role of MALDI-TOF MS in microbial identifications.

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A cultivation-based study of the microbial diversity of cellular phone screens led to the isolation of a Gram-stain-positive, aerobic, rod-shaped and non-endospore-forming bacterium, designated S2T63, exhibiting phenotypic and genotypic characteristics unique to the type strains of closely related species. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain is a member of Microbacterium, and most closely related to Microbacterium aurantiacum IFO 15234 and Microbacterium kitamiense Kitami C2. The DNA-DNA relatedness values of the strain S2T63 to M. aurantiacum KACC 20510, M. kitamiense KACC 20514and Microbacterium laevaniformans KACC 14463 were 65 % (±4), 29.5 % (±3) and 55.9 % (±4), respectively. The genomic DNA G+C content was 71.8 mol%. The major fatty acids were anteiso-C15 : 0, iso-C16 : 0, C16 : 0 and anteiso-C17 : 0. The main polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and two unidentified polar lipids. The peptidoglycan contained the amino acids glycine, lysine, alanine and glutamic acid, with substantial amounts of hydroxy glutamic acid detected, which is characteristic of peptidoglycan type B1α. The predominant menaquinones were MK-12 and MK-13. Rhamnose, fucose and galactose were the whole-cell sugars detected. The strain also showed biofilm production, estimated by using crystal violet assay. Based on the results of the phenotypic and genotypic characterizations, it was concluded that the new strain represents a novel species of the genus Microbacterium, for which the name Microbacteriumtelephonicum is proposed, with S2T63T (=MCC 2967=KACC 18715=LMG 29293) as the type strain.

A novel bacterial strain, designated S5H2222T, was isolated form the screen of a cellular phone. The cells were Gram-stain-positive, rod-shaped, aerobic and motile, and endospores are formed. S5H2222T grew as pale white colonies on trypticase soy agar and the best growth was observed at 37 °C (10-55 °C) and at pH 7.0 (5.0-9.0). S5H2222T could tolerate up to 10 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences placed this strain within the genus Lysinibacillus and it exhibited high 16S rRNA gene sequence similarity to Lysinibacillus halotolerans LAM612T (97.8 %), Lysinibacillus chungkukjangi 2RL3-2T (97.4 %) and Lysinibacillus sinduriensis BLB-1T (97.2 %). The DNA-DNA relatedness of the strain with L. halotolerans JCM 19611T, L. chungkukjangi KACC 16626T and L. sinduriensis KACC 16611T was 57, 64 and 55 % respectively. The genomic DNA G+C content was 39.8 mol%. The major fatty acids of S5H2222T were iso-C15 : 0, anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. MK-7 was the only menaquinone and the main polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine, four unidentified polar lipids were also present. The diagnostic amino acids in the cell wall peptidoglycan contained Lys-Asp (type A4α). On the basis of the results of the phenotypic and genotypic characterizations, it was concluded that S5H2222T represents a novel species of the genus Lysinibacillus, for which the name Lysinibacillus telephonicus sp. nov. is proposed. The type strain is S5H2222T (=MCC 3065T=KACC 18714T=LMG 29294T).