Isolation and characterization of chitinolytic fast-growing bacteria from marine environment in Vietnam

Chitin is found in tremendous quantities in nature, especially in the marine environment. This polymer has a stable structure that requires a relatively long time to degrade. As a result, fast-growing microorganisms capable of degrading chitin might be a potential approach in responding to the hydrolysis of this abundant material. This study focused on the isolation of chitinolytic fast-growing bacteria from marine environment in Vietnam, determined their biochemical characteristics, and generally evaluated the relationship between the presence of some important chitinase genes (mostly extracellular) and chitin degradation capacity of the isolates. Crucial chitinase genes were detected via PCR using degenerate primers, while chitin hydrolysis ability was determined via enzymatic measurements, assessing strains' growth on chitin and chitin hydrolysate composition. The results showed that fourteen chitinolytic fast-growing bacteria isolated from seawater in Vietnam belonged to the family Vibrionaceae and the majority of them possessed all five tested chitinase genes including VCA0027 (chitinase), VC1952 (endochitinase), VC0769 (endochitinase), VCA0700 (chitodextrinase), VC2217 (hexosaminidase). V. natriegens isolates N5.3, N7.2, and 10.3, which lack VC1952 and VC0769, exhibited significantly reduced enzymatic activities, weak chitin hydrolysis, and limited growth on chitin substrates, highlighting the crucial role of these genes for efficient chitin degradation.