Characterization of a novel lytic bacteriophage VPMCC14 which efficiently controls Vibrio harveyi in Penaeus monodon culture.

Vibrio harveyi causes luminous vibriosis diseases in shrimp, which lead to shrimp mortalities. Considering the emergence of antibiotic-resistant bacteria, a Vibrio-infecting bacteriophage, VPMCC14, was characterized, and its lysis ability was evaluated on a laboratory scale. VPMCC14 was shown to infect V. harveyi S5A and V. harveyi ATCC 14126. VPMCC14 also exhibited a latent period of 30 min, with a burst size of 38 PFU/cell on its propagation strain. The bacteriophage was stable at a wide range of pHs (3-9), temperatures (0-45°C), and salinities (up to 40 ppt). VPMCC14 exhibited strict virulence properties as the bacteriophage entirely lysed V. harveyi S5A in liquid culture inhibition after 5 h and 4 h at very low MOIs such as MOI 0.1 and MOI 1, respectively. VPMCC14 could control V. harveyi infection in aquariums at MOI 1 and decrease the mortality of Penaeus monodon challenged by V. harveyi. VPMCC14 genome was 134,472 bp long with a 34.5 G+C% content, and 240 open reading frames. A unique characteristic of VPMCC14 was the presence of the HicB family antitoxin-coding open reading frame. Comparative genomic analyses suggested that VPMCC14 could be a representative of a new genus in the Caudoviricetes class. This novel bacteriophage, VPMCC14, could be applied as a biocontrol agent for controlling V. harveyi infection.

Production of chitin and bioactive materials from Black tiger shrimp (Penaeus monodon) shell waste by the treatment of bacterial protease cocktail.

The main objective of this study was to obtain chitin in pure form from a new crustacean waste material for industrial applications. Black tiger shrimp shell wastes are a rich source of protein and valuable bioactive carbohydrate polymers such as chitin. After removal of carotenoid, Black tiger shrimp shell wastes (BTSHWs) were treated with chemicals and protease enzyme to extract chitin. Box-Behnken response surface methodology was applied to optimize the deproteinization process to obtain chitin. At optimal pH (8.82), temperature (50.05 °C), agitation speed (100.98 rpm), enzyme substrate ratio of 1:8 (wv-1) and 72 h of incubation with Paenibacillus woosongensis TKB2 crude protease cocktail, 80 % deproteinization was found along with 77.28 % recovery of chitin. The valuable oligopeptides were determined by MALDI-TOF analysis and analysis of adequate amount of free amino acids in protein hydrolysate from BTSHW, indicating a high nutritional value used for food, feed or as a nitrogen source in growth medium for microorganisms. The chitin obtained was compared with the commercial chitin using scanning electron microscopy, Fourier transform infrared spectrometer, X-ray diffraction and 13C CP/MAS-NMR. Chitin obtained from crude protease treatment showed comparable physicochemical and structural properties to those of the commercial chitin. The carotenoid obtained after treatment can be used for medicinal purpose.