Pseudomonas soli str. VMAP1: BACTERIUM WITH BIOCONTROL PROPERTIES BELONGING TO A LITTLE-STUDIED Pseudomonas sp.

TADEO GALVÁN; VALERIA CONFORTE; JOÃO SETUBAL; GRABRIELA PETROSELLI; ROSA ERRA BALSELLS ; NATALIA MIELNICHUK; ADRIÁN VOJNOV; PABLO YARYURA; MARIA ISABEL BIANCO

Chapalmalal

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

SAMIGE

Pseudomonas soli was identified as a new species of Pseudomonas in 2014. Up to date, eight P. soli strains have been isolated worldwide and there is only phenotypic informationregarding two strains: LMG 27941 and VMAP1. We previously isolated VMAP1 from therhizospheric soil of healthy tomato (Solanum lycopersicum) plants. In a previous work, westudied the biocontrol activity of VMAP1 against Xanthomonas vesicatoria (aphytopatogenic bacteria) on tomato plants. The treatment with VMAP1 (applied byirrigation) and with its cell-free supernatant (applied by foliar spray) reduced the severity ofthe infection caused by X. vesicatoria by 44 % and 75 %, respectively. This triggered ourinterest in studying VMAP1 and the compounds it synthesizes, especially since theinformation available about P. soli is very scarce. Here, we present some results of theexhaustive genomic and phenotypic characterization of VMAP1 that we are carrying out.We first analyzed VMAP1 growth in different culture conditions and some phenotypiccharacteristics. We also investigated compounds produced by this bacterium. VMAP1 grewbetter at 20 and 28 °C than at 37 °C and tolerated 40 °C but not 45 °C. It also grew in a pHrange of 5 to 10 and tolerated pH 4, 11 and 12. In addition, VMAP1 grew in mediumcontaining up to 8 % NaCl and tolerated up to 16 % NaCl. VMAP1 presented twitching,swarming and swimming motilities. Most VMAP1 cells showed one unique polar flagellum,whereas a few ones showed two flagella. Biofilm assays in minimal and rich media areongoing. Preliminary results suggested that VMAP1 presents a low surface adhesioncapacity and consequent scanty biofilm formation in minimal medium. In addition, wesequenced and assembled the VMAP1 genome. Using different bioinformatics tools, wesearched biosynthetic gene clusters (BGCs) involved in the synthesis of compounds withantimicrobial, antibiofilm and/or biocontrol/plant-growth promoting properties. We foundBGCs encoding xantholysins (cyclic lipopeptides), HCN, rhamnolipids, pyoverdine(siderophore), tailocin (bacteriocin), lytic enzymes and indole acetic acid among others.Regarding the production of polysaccharides, we only found the alginate operon. Until now,we confirmed in vitro production of HCN, rhamnolipids and xantholysins A, B and C. Wedid not find genes encoding glycoside-modifying proteins; however, we found genesencoding a multidrug efflux system. This could explain why VMAP1 showed in vitrosensitivity to some antibiotics (kanamycin, gentamicin and polymyxin B) and resistance toothers (ampicillin, chloramphenicol and streptomycin). Together, these results contribute tounderstanding the VMPA1 physiology and the mechanisms that confer this bacterium itsbiocontrol properties. Furthermore, understanding the metabolic characteristics of VMAP1will provide information on its potential uses in the biotechnology industry.