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

LUDUEÑA, L.; ANZUAY, MS; TORRES TEJERIZO, G; TAURIAN, T1

Congreso; XVII Congreso Argentino de Microbiología General. Sociedad Argentina de Microbiología General-SAMIGE; 2023

Phosphorus is an essential macronutrient required for plant growth and development. Most cultivated soils have insufficient amounts of available P, being a worldwide limiting nutrient for agricultural production. Phosphate solubilizing bacteria (PSB) are a group of bacteria that have the ability to solubilize insoluble phosphate, and by this trait they are considered one of the most effective strategies to supply phosphorus (P) to soil and plants. Currently, molecular techniques have made it possible to elucidate important processes occurring in the rhizosphere. Among them, analysis of gene expression is a useful tool to understand the mechanisms involved in bacterial response to nutritional deficiencies. The aim of this work was to study global gene expression of the PSB Serratia sp. S119 under phosphorus deficient growth conditions.For this purpose, methodology employed consisted of analyzing the expression of all mRNAs 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 using a 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 RNA protect kit (QIAGEN), respectively. RNA-enriched samples were analyzed by massive RNA sequencing. RNA Library preparation for Illumina MiSeq sequencing technology was performed using the TrueSeqStranded mRNA kit (ILLUMINA). Each treatment had three biological replicates. Reads quality was assessed using FastQC. Satisfactory readings were aligned to S119 genome sequence using Bowtie2 and visualization of results was done using ReadXplorer program. Transcriptomic results from the two growth conditions were statistically analyzed to obtain differential expressed genes (DEG) using the DESeq tool. A biological and functional assignment of DGE were made using Blast2GO, KEGG, COG and PFAM. From a total of 4792 coding sequences present in S119 genome, 4783 genes were represented in this RNAseq study (99.8%). Among those, 788 (16.5%) genes were found to be differentially expressed (DEG adj p-value ≤0.05). Those genes that presented a fold change (FC) >1, or < -1 were analyzed using databases to assign biological function to each of them. Results indicated that DEG belonged to the following categories: biological processes, cell signaling, cellular components, and hypothetical proteins, being the first one the numerous categories (covering both, overexpressed and repressed genes). The sequence analysis of DEG indicated that they code for permeases, general metabolism, membrane transporters and cell signaling processes. Under P deficiency ABC transporters genes were the most expressed DEG. These preliminary results allow us to suggest a multigenic response of BSP Serratia sp. S119 to P deficient environment, being membrane transporters crucial for this phenotype.