The present survey considers our studies made over the last decades on polymer films based on the purple membranes of a microorganism Halobacterium salinarum containing bacterio-rhodopsin, a light-sensitive protein and a natural photochrome. The review discusses the photo-chemistry of bacteriorhodopsin in polymer films depending on the change of the protein environment through the factors of dehydration, chemical modification through additives, bacteriorhodopsin monomerization, direct modification of the protein by means of chromophore substitution and alteration of the protein through both genetic manipulation in the primary sequence of the bacteriorhodopsin molecule and chromophore substitution. The review also goes into the studies of spectral and kinetic properties of the so-called non-photochromic bacteriorhodopsin films (modified with hydroxylamine and its O-substituted derivatives) in the aspect of possible use of these films for write-once recording of optical information. All optimizations of bacteriorhodopsin optical characteristics are discussed in the frames of possible application of bacteriorhodopsin films for optical memories.