I'm trying to identify the species of even genus of this bacteria I have grown in the lab but due to its unique colony appearance the bacteria I am getting from decision trees are not showing any like it. The edges are white but the centre is dark and it makes the agar around it darken as it grows. Under the microscope it is a gram positive rod, oxidase and catalase positive, motile, not anaerobic, positive nitrate, positive bile aesulin, negative urease, b haemolysis. Any ideas on what this could be would be greatly appreciated!