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An easy engineerable bacterial chassis opens a spectrum of biomedical applications such as antigen delivery or drug production and delivery. However, most cell walled bacteria are readily recognized and cleared by the immune system and encode various effector proteins potentially interacting with the target species. <i>Mycoplasma feriruminatoris</i>, a cell wall less minimal organism with excellent growth attributes, was genetically engineered to stably incorporate foreign DNA fragments into the chromosome in a single step without any remaining marker gene presence using orthogonal recombinase system. Using this mechanism, we characterized and developed promoters and proofed their functionality including a kill-switch based on a temperature-sensitive promoter that drives expression of a toxin from a toxin-antitoxin system. Additionally, we inserted a newly designed functional dynamic display system based on a modified monomeric streptavidin at the surface of the bacterium. The engineered strain has great potential such as to deliver <i>Mollicutes</i> vaccine antigens to different livestock species among other applications.