TRANSCRIPTOME ANALYSIS OF THE BIOFERTILIZER STRAIN Serratia sp. S119 UNDER PHOSPHATE DEFICIENT GROWTH CONDITIONS

LUDUEÑA, L., ANZUAY, M.S., TORRES TEJERIZO, G., TAURIAN, T.

Chapadmalal

Congreso; XVIII Congreso de la Sociedad Argentino de Microbiología General; 2023

SAMIGE

Phosphorus is an essential macronutrient required for plant growth and development.Most cultivated soils have insufficient amounts of available P, being a worldwide limitingnutrient for agricultural production. Phosphate solubilizing bacteria (PSB) are a group ofbacteria that have the ability to solubilize insoluble phosphate, and by this trait they areconsidered one of the most effective strategies to supply phosphorus (P) to soil and plants.Currently, molecular techniques have made it possible to elucidate important processesoccurring in the rhizosphere. Among them, analysis of gene expression is a useful tool tounderstand the mechanisms involved in bacterial response to nutritional deficiencies. Theaim of this work was to study global gene expression of the PSB Serratia sp. S119 underphosphorus deficient growth conditions.For this purpose, methodology employed consisted of analyzing the expression of allmRNAs present in the BSP S119 strain when it was grown under P deficient conditions(VMM+ Ca3(PO4)2 5 g/L) and with an optimal amount of P (VMM+ 2 mM K2HPO4) by usinga transcriptomic technique. Strain S119 was grown until exponential phase (107 CFU/ml)and RNA extraction and purification was done according to literature and by using the RNAprotect kit (QIAGEN), respectively. RNA-enriched samples were analyzed by massive RNAsequencing. RNA Library preparation for Illumina MiSeq sequencing technology wasperformed using the TrueSeqStranded mRNA kit (ILLUMINA). Each treatment had threebiological replicates. Reads quality was assessed using FastQC. Satisfactory readings werealigned to S119 genome sequence using Bowtie2 and visualization of results was doneusing ReadXplorer program. Transcriptomic results from the two growth conditions werestatistically analyzed to obtain differential expressed genes (DEG) using the DESeq tool. Abiological and functional assignment of DGE were made using Blast2GO, KEGG, COG andPFAM. From a total of 4792 coding sequences present in S119 genome, 4783 genes wererepresented in this RNAseq study (99.8%). Among those, 788 (16.5%) genes were foundto be differentially expressed (DEG adj p-value ≤0.05). Those genes that presented a foldchange (FC) >1, or < -1 were analyzed using databases to assign biological function to eachof them. Results indicated that DEG belonged to the following categories: biologicalprocesses, cell signaling, cellular components, and hypothetical proteins, being the first onethe numerous categories (covering both, overexpressed and repressed genes). Thesequence analysis of DEG indicated that they code for permeases, general metabolism,membrane transporters and cell signaling processes. Under P deficiency ABC transportersgenes were the most expressed DEG. These preliminary results allow us to suggest amultigenic response of BSP Serratia sp. S119 to P deficient environment, being membranetransporters crucial for this phenotype.