Bioconversion of chitin and concomitant production of chitinase and N?acetylglucosamine by novel Achromobacter xylosoxidans isolated from shrimp waste disposal area
Marine wastes pose a great threat to the ecosystem leading to severe environmental hazards and
health issues particularly the shellfish wastes. The shellfish waste which contains half of the amount
of chitin can be efficiently transformed into useful products. Various approaches for the hydrolysis of
chitin like physical, chemical, and enzymatic processes are there. Still, the use of enzyme chitinase is
well documented as an effective and eco-friendly method. The present study summarizes the isolation
of chitinase enzyme producing bacteria from different shrimp waste disposal sites in Parangipettai
(India), and the possible use of an enzyme hydrolyzate as an immunostimulant to Asian Seabass (Lates
calcarifer). The potential chitinase-producing bacteria were identified by 16S rRNA gene sequencing
as Stenotrophomonas maltophilia. After purification, the chitinase specific activity was 5.01 (U/ml) and
the protein content was 72 mg and the recovery rate was 48.06%. The optimum pH and temperature
for the chitinolytic activity were 6.5 and at 35–50 °C, respectively. The animal experiment trial was
done with our feed supplements which included 0.0 (control), 0.5%, 1% and 2% of chitin degraded
product. All the supplementary feed had an optimal 42% (w/w) of crude protein. The feed protein level
was 41–43% on average and gross energy was 13–17 kcal/g and the feed was observed to exhibit a
significantly higher (p < 0.05) survival rate, condition factor, specific growth rates, and body weight
gain was also found to be promising compared to other fishes fed with control diet only. The red
blood cells (RBC) and white blood cell (WBC) counts were found to increase significantly after being
challenged with infection in animals fed with chitin derivatives from 1st week to 3rd week when
compared to the control. The hematocrit (Hct) values were low on the 2nd and 3rd week in infected
fish fed with chitin derivatives. This low level was due to infection lyses of the red blood cells and
increased nitro blue tetrazolium reduction. The control diet-fed fish showed 70% mortality but the