An Exochitinase with N-Acetyl-β-Glucosaminidase-Like Activity from Shrimp Head Conversion by Streptomyces speibonae and Its Application in Hydrolyzing β-Chitin Powder to Produce N-Acetyl-d-Glucosamine

Marine chitinous byproducts possess significant applications in many fields. In this research, different kinds of fishery chitin-containing byproducts from shrimp (shrimp head powder (SHP) and demineralized shrimp shell powder), crab (demineralized crab shell powder), as well as squid (squid pen powder) were used to provide both carbon and nitrogen (C/N) nutrients for the production of an exochitinase via Streptomyces speibonae TKU048, a chitinolytic bacterium isolated from Taiwanese soils. S. speibonae TKU048 expressed the highest exochitinase productivity (45.668 U/mL) on 1.5% SHP-containing medium at 37 °C for 2 days. Molecular weight determination analysis basing on polyacrylamide gel electrophoresis revealed the mass of TKU048 exochitinase was approximately 21 kDa. The characterized exochitinase expressed some interesting properties, for example acidic pH optima (pH 3 and pH 5–7) and a higher temperature optimum (60 °C). Furthermore, the main hydrolysis mechanism of TKU048 exochitinase was N-acetyl-β-glucosaminidase-like activity; its most suitable substrate was β-chitin powder. The hydrolysis experiment revealed that TKU048 exochitinase was efficient in the cleavage of β-chitin powder, thereby releasing N-acetyl-d-glucosamine (GlcNAc, monomer unit of chitin structure) as the major product with 0.335 mg/mL of GlcNAc concentration and a yield of 73.64% after 96 h of incubation time. Thus, TKU048 exochitinase may have potential in GlcNAc production due to its N-acetyl-β-glucosaminidase-like activity.

Enzymatic hydrolysis of chitin pretreated by bacterial fermentation to obtain pure N-acetyl-d-glucosamine

In this study, we propose a novel biological fermentation method to process chitin powder utilizing the bacteria Chitinolyticbacter meiyuanensis SYBC-H1.

Pembuatan Kitosan dari Cangkang Udang sebagai Adsorben Emas (Au)

[Title: Making Chitosan From Shrimp Cup As Gold (Au) Adsorben]. This study aims to make chitosan from shrimp shell as golden adsorbent. Stages of chitosan preparation include demineralization stage using 1,5M HCL, deproteination stage using 3.5% NaOH to obtain chitin powder, then followed by chitin deacetylation stage using 60% NaOH to produce an anime that is chitosan. Subsequently, the chitosan obtained was characterized, analyzed functional group with FTIR and determined its adsorption capacity against Au metal ion, Au content in the sample before and after adsorption was measured using AAS. The results showed chitosan characterization as follows: rendeman 45.83%, have powder texture, white colour, odourless, have moisture content 1.55%, perfectly soluble in glacial acetic acid 2% and purple positive with ninhydrin solution showed chitin has turned into chitosan. Based on calculations from the results of the resulting chitosan FTIR data has a degree of deacetylation 71.17%. From the result of analysis by using AAS that chitosan obtained able to adsorb Au metal from concentration 8.55 ppm decrease until 5,09 ppm with adsorption percentage equal to 40.46%.

Preparation of Size-Controlled Silver Nanoparticles and Chitin-Based Composites and Their Antimicrobial Activities

A simple method for the preparation of size-controlled spherical silver nanoparticles (Ag NPs) was reported for their generation by autoclaving a mixture of silver-containing glass powder and glucose. The particle size is regulated by the glucose concentration, with concentrations of 0.25, 1.0, and 4.0 wt% glucose providing small (3.48±1.83 nm in diameter), medium (6.53±1.78 nm), and large (12.9±2.5 nm) particles, respectively. In this study, Ag NP/chitin composites were synthesized by mixing each of these three Ag NP suspensions with a <5% deacetylated (DAc) chitin powder (pH 7.0) at room temperature. The Ag NPs were homogenously dispersed and stably adsorbed onto the chitin. The Ag NP/chitin composites were obtained as yellow or brown powders. Approximately 5, 15, and 20 μg of the small, medium, and large Ag NPs, respectively, were estimated to maximally adsorb onto 1 mg of chitin. The bactericidal and antifungal activities of the Ag NP/chitin composites increased as the amount of Ag NPs in the chitin increased. Furthermore, smaller Ag NPs (per weight) in the chitin composites provided higher bactericidal and anti-fungal activities.

Nanofibrillation of Dry Chitin Powder by Star Burst System

Chitin nanofibers were prepared from dry chitin powder by nanofibrillation using a Star Burst instrument employing a high-pressure water jet system. FE-SEM micrographs showed that the nanofibers became thinner as the number of Star Burst passes increased. Fibrillation in an acidic condition made the chitin fibers thinner than those in a neutral condition. The transmittance spectra of chitin nanofiber/acrylic resin composites led us to the same conclusion. In addition, chitin nanofibers prepared by treatment consisting of five Star Burst passes in the neutral condition were thinner than the previously reported nanofibers. X-ray diffraction profiles showed that the Star Burst system did not damage the chitin nanofibers and did not reduce their crystallinity.

PREPARASI DAN KARAKTERISASI KITIN DARI KULIT UDANG PUTIH (Litophenaeus vannamei)

Chitin is one of the most abundant natural polysaccharides produced by many living organisms; it is usually found as a component of crustacean shells. In this paper, Chitin have been isolated from white shrimp (Litophenaeus vannamei). The preparation of chitin using chemical products to deproteinize and demineralize the source material. Characterization included determination of water, ash, fat and protein degree; moreover chitin powder characterize with FTIR and XRD spectroscopy. The result showed that process efficiency of chitin from white shrimp (Litophenaeus vannamei) was 20.95%, with degree of water, ash, fat and protein were 5.39, 2.66, 1.54 and 36.16%, respectively.