A Review of Various Sources of Chitin and Chitosan in Nature

Chitin was first discovered by its name from the Greek word“chiton”,which means“mail coat”.It is indeed a polysaccharide made up of naturally occurring acetyl-D-glucosamine monomers.Hatchett was the first researcher who extracted chitin from the shells of mollusks(crabs and lobsters),prawns,and crayfish in 1799.Later in 1811,Henri Braconnot discovered chitin in the cell walls of mushrooms and called it“fungine”.Chitin and chitosan are abundant in the biosphere as essential components of many organisms’exoskeletons and as by-products of the global seafood industry.The biopolymer must be deacetylated before chitosan can be produced.It can also be extracted using microbes in a biological extraction procedure.The development of products that take advantage of the bioactivities of the existing primary commercial source of chitin(crustacean)has lagged expectations.Also,the disadvantages of the present commercial source such as seasonality and competition for other uses among others has been one of the driving forces towards seeking alternative sources of chitin and chitosan in nature.This review highlights some of the efforts made by environmental scholars to locate possible commercial sources of chitin and chitosan in nature over time.

Effect of Probiotics on Juvenile Tachypleus tridentatus Gut Microbiota

The population of tri-spine horseshoe crabs(HSCs)Tachypleus tridentatus has sharply decreased in recent decades.Domestication and manual releasing are now used to recover it.In order to accelerate the growth of T.tridentatus in indoor environment,in this study,gut microbiota of 2nd instar T.tridentatus was supposed to be improved by putting probiotics in water environment and thus promoted the health and growth of the host.Using 16S rRNA sequencing of gut samples,we examined the intestinal microbiome of juvenile HSCs and studied the effect of probiotics.Results showed that there was no significant difference between groups fed with high and low concentrations(1×10^(7),1×10^(12)CFU mL^(−1))of Bacillus subtilis and high concentration(1×10^(12)CFU mL^(−1))of Lactobacillus,and no significant difference compared with the control group,but the diversity of Lactobacillus group with low concentration(1×10^(7)CFU mL^(−1))was significantly higher than those of other groups.Microbial-mediated functions predicted by PICRUSt showed that‘Cellular Processes’,‘Metabolism’and‘Organismal Systems’pathways significantly increased in groups of Bacillus subtilis and Lactobacillus group with low concentration.The results showed that two types of probiotics with different concentrations have other effects on the structure,richness and function of intestinal microbes.By searching the literature and conducting pre-experiments,we forecasted the short time of breeding under the probiotic environment may not have much effect.The present study for the first time investigated the impact of probiotics on gut microbiota of juvenile HSCs and found them may benefit for the growth and health of HSCs.