Internal plant tissue colonisation has made endophytic bacteria valuable for agriculture as a tool to improve crop performance particularly for those bacteria having traits such as plant growth promotion (PGP). This project involved screening and identifying endophytic bacterial strains, sourced from the bacterial collection available at the Institute of Technology Carlow, with the potential to enhance growth rate in bio-energy plant crop species. In the initial stage under greenhouse condition, a total of 140 strains in master mix (MM) groups of 10 strains, were inoculated into Rye Grass. The inoculated Rye Grass seeds were sown in pots and arranged in complete randomised design and their growth was monitored for a period of 3 months. The plant fresh weights (FW) and dry weights (DW) were used as growth parameters. Three MMs (comprising 30 strains) showed PGP potential in Rye Grass, significantly increased the mean FW and DW of Rye Grass plants compared to the negative controls. The 30 selected strains were further characterised for PGP traits under in vitro study. Results showed three strains inhibited Pythium spp. growth in dual culture assay, whereas the culture filtrates to quantify gluconic acid production necessary for inorganic phosphate solubilisation, had six strains recording more than 20mg/ml of gluconic acid production. Ten strains showed Indole acetic acid (IAA) production in the range (10-18 µg/ml) while three strains showed 1-aminocylopropane-1-carboxylic acid (ACC) deaminase activity. This study indicates that the selected bacterial endophytes have the potential for PGP and development in plant crops.