Involved in the degradation of ectoine, which allows H.elongata to utilize ectoine as both a carbon and a nitrogen source for growth. Probably catalyzes the NAD(+)-dependent oxidation of L-aspartate-semialdehyde to L-aspartate. H2O + L-aspartate 4-semialdehyde + NAD(+) = 2 H(+) + L-aspartate + NADH Cells lacking this gene are unable to grow on ectoine as sole carbon source. Belongs to the aldehyde dehydrogenase family.