Chitinases synthesized by plants, fungi, insects and bacteria have a huge potential owing to its wide range of applications. In this work we review generalities about chitin, chitosane, chitinases and chitosanases from bacteria and their use in the production of chitin-oligosaccharides. This kind of biomolecules has created a diversified biotechnology market, including unlimited applications such as food additives and biopreservative, in biomedical applications focused mainly on anti-tumor activities, as antioxidants and anti-diabetics. In agriculture chitin-oligosaccharides has been applied as nodulation factors, osmoprotectors agents and antioxidants to benefit crop growth. It is important to note the potential use of chitinases biosynthesized by Bacillus thuringiensis, the most important biopesticide worldwide. Chitinases from B. thuringiensis been used recently to generate chitin-oligosaccharides with antimicrobial activity, in particular against food-borne pathogenic bacteria of importance in public health.