Draft Genome Sequence of an Epiphytic Strain, Bacillus sp. Strain WL1, Isolated from the Surface of Nostoc flagelliforme Colonies in Yinchuan, Ningxia, China

ABSTRACT Bacillus species are Gram-positive, aerobic, spore-forming bacteria that are widely spread in soil, dust, and water. One strain, Bacillus sp. strain WL1, was isolated from the surface of the cyanobacterium Nostoc flagelliforme in Yinchuan, Ningxia, China. The draft genome sequence of this strain was 5.62 Mbp.

N ostoc flagelliforme is a terrestrial blue-green alga that is distributed throughout the arid and semiarid steppes of the western and northwestern parts of China (1). It exhibits a predominantly filamentous colony shape. It was previously reported that the epiphytic bacteria of N. flagelliforme were mainly Bacillus spp., including Bacillus subtilis, B. licheniformis, B. megaterium, B. cereus, and B. circulans. In this study, we attempted to isolate and identify those epiphytic bacteria on the surface of N. flagelliforme collected on the eastern side of Helan Mountain in Yinchuan, Ningxia, China (2). The epiphytic bacteria were washed from the N. flagelliforme filaments with sterilized water and cultivated with Luria-Bertani (LB) solid medium at 37°C. One dominant strain with a uniform shape and size was isolated. The 16S rRNA gene was amplified with the primers 27F (59-AGAGTTTGATCCTGGCTCAG-39) and 1492R (59-GGTTACCTTGTTACGACTT-39) as previously described (3). This strain was identified as a Bacillus sp. based on 16S rRNA gene sequencing and named Bacillus sp. strain WL1.
Bacillus sp. strain WL1 was stored in glycerol solution (20%, vol/vol) at 280°C. The strain was streaked onto solid LB medium and cultivated at 37°C. One single Bacillus sp. strain WL1 colony was inoculated into liquid LB medium for shake cultivation overnight at 30°C, and the cell culture was collected by centrifugation for DNA extraction using a DNeasy PowerMax soil kit (Qiagen, Germany) (4). The DNA was used to build a 2 Â 150-bp sequencing library and sequenced using the Illumina HiSeq 2500 platform at Genesky Bio-Tech Co., Ltd. (Shanghai, China); the raw reads of Bacillus sp. strain WL1 were filtered using Trim Galore v0.4.4 (http://www.bioinformatics.babraham.ac.uk/projects/trim_galore/). The total number of reads from the paired-end sequencing (2 Â 150 bp) was 4,372,767, and a total of 658.84 Mbp of data was obtained. The sequence coverage of this genome was 117Â. The draft genome sequences were assembled using SOAPdenovo v2.04 with default parameters, and the resulting assembly was used for further genomic analysis (5,6). The gaps in the draft genome sequence were corrected using GapCloser v1.12 software (6). RNAmmer v1.2 and tRNAscan-SE v2.0 were used for rRNA and tRNA prediction, respectively (7,8). Glimmer3 v3.02 (http://ccb.jhu.edu/software/glimmer/index.shtml) was used for gene prediction. Default parameters were used for all software unless otherwise specified.
A total of 420 contigs comprised the draft genome assembly of Bacillus sp. strain WL1. The total length of the draft genome sequence is 5,624,893 bp, with a GC content of 35.2%. The length of the largest contig is 226,802 bp, and the N 50 contig length is 38,057 bp. A total of 5,697 genes are predicted in the draft genome sequence of Bacillus sp. strain WL1, and the average gene length is 804.9 bp. The gene length composed 81.1% of the whole draft genome sequence. The public version of the draft genome was annotated using PGAP v5.1 through NCBI (9), and the annotated genome sequence was deposited in the GenBank database (9). Genome-based phylogenetic analysis suggested that this strain was most similar to B. cereus ATCC 14579.
Data availability. The draft genome sequence of Bacillus sp. strain WL1 was deposited in GenBank under accession number JAGKST000000000, BioProject accession number PRJNA733760, BioSample accession number SAMN19458293, and SRA accession number SRR14099160.

ACKNOWLEDGMENTS
This work has received support from the self-determined research funds of CCNU from the Colleges' Basic Research and Operation fund of the MOE (grant number CCNU16GD012) and the Key Project of Natural Science of Shaanxi Province, China (grant number 2020JZ-51).