The black soldier fly (BSF), Hermetia illucens, is known as a beneficial insect and feeds on organic materials derived from animals and human, resulting in reduction of food waste and conversion of organic materials. Despite of many studies on the BSF, there have been no reports of cloned genes encoding serine proteases in the BSF. Thus, the primary objective of this study is to clone and to investigate expression pattern of genes encoding serine proteases released from the midgut of the BSF larvae in order to gain a better understanding of expression mechanism of serine proteases. We cloned two serine proteases from the BSF larva. Based on phylogenetic tree analysis, one was chymotrypsin, the other was trypsin. The open reading frame (ORF) of chymotrypsin was 804bp, which encoded a polypeptide of 267 amino acids. In case of trypsin, the ORF was 744bp, which encoded a polypeptide of 247 amino acids. To investigate expression pattern of two serine proteases, we conducted semi-quantitative RT-PCR at different tissues and different developmental stages. A chymotrypsin and trypsin transcripts were revealed strongly in mid gut. Especially, a chymotrypsin was detected largely at feeding stage more than molting stage, while trypsin was expressed similarly between feeding stage and molting stage

The black soldier fly (BSF), Hermetia illucens, is known as a beneficial insect and feeds on organic materials derived from animals and human, resulting in reduction of food waste and conversion of organic materials. Despite of a lot of study about the BSF, there is a less information about composition of digestive enzyme of the BSF larva. Experimentally, there is no evidence about characterization of digestive enzyme of the BSF. We investigated biochemical property of digestive enzyme released from the salivary and gut of the BSF. Through digestive enzyme assay, we found that the BSF has amylase, lipase and protease activity in gut extracts, resulting in that the BSF belong to polyphagous insect group. In the BSF gut, trypsin-like protease activity showed one peak at various temperature and pH condition. This result means the BSF has probably a similar form of trypsin-like enzymes. On study of comparison of enzyme activity between the BSF and the housefly using the apiZYM kit, the BSF had more strongly digestive enzyme activity than one of the housefly about leucine arylamidase, alpha-galactosidase, beta-galactosidase, alpha-mannosidase and alpha-fucosidase. This finding supports that the BSF can ingest raw waste far more efficiently than any other known species of fly as reported previously.

This study aimed to produce fermented soy-powder milk (FSPM) with Lactobacillus plantarum P1201 and to evaluate its anti-obesity activity. Isoflavone and conjugated linoleic acid (CLA) of unfermented soy-powder milk (UFSPM) and FSPM and were analyzed via high-pressure liquid chromatography (HPLC) and gas chromatography (GC). Their inhibitory activities against α-glucosidase, α-amylase, and pancreatic lipase were assayed. Their anti-obesity activities were evaluated on the basis of their inhibitory effects on adipocyte differentiation in 3T3-L1 cells, and the expression of mRNAs associated with adipogenesis and lipid metabolism were analyzed via real time-polymerase chain reaction (RT-PCR) and quantitative PCR (qPCR). FSPM with L. plantarum P1201 increased the isoflavone aglycones (daidzein, glycitein, and genistein) content and produced CLA in soy-powder milk (SPM), both of which possessed bio-activity. Both UFSPM and FSPM showed dose-dependent inhibitory activity for α-glucosidase, α-amylase, and pancreatic lipase. FSPM, but not UFSPM, suppressed adipogenesis in 3T3-L1 cells and reduced their triglyceride content by 23.1% after treatment with 1,000 μg/mL of FSPM, compared with the control group. The anti-obesity effect of FSPM can be attributed to CLA and isoflavone aglycones, which targeted CCAAT/enhancer binding protein α (C/EBP-α) and down-regulated lipoprotein lipase (LPL), adiponectin, adipocyte fatty acid-binding protein (aP2), fatty acid synthase (FAS), and acetyl CoA carboxylase (ACC) mRNA. Furthermore, FSPM enhanced the inhibitory activity of glucosidase and pancreatic enzymes and anti-obesity activity. Further studies are required to investigate whether the anti-obesity effect of FSPM persists in an in vivo mouse model of diet-induced obesity.

The antioxidant and digestive enzyme inhibitory effects of Eisenia bicyclis extracted by various extraction methods (RE, reflux extraction; SE, ultrasonification extraction; AE, autoclave extraction; LE, low-temperature high-pressure extraction) were investigated. The extraction yield (55.21%) and the laminarin (39.03%), fucoidan (24.75%), total polyphenol (115.68 mg GAE/g) and flavonoid (36.67 mg RHE/g) contents of AE were higher than those in other methods. The DPPH radical (86.60%, 500 mg%), ABTS radical (58.56%, 25 mg%), nitrite (86.38%, 100 mg%) scavenging activities of the Eisenia bicyclis extracted by AE were higher than those of Eisenia bicyclis extracted by other methods. The ABTS radical and nitrite scavenging activities were above 98% in all tested Eisenia bicyclis extracts and these activities were dependent on its concentration. The inhibitory effects of AE against amylase (50 mg%) and α-glucosidase (5 mg%) were 64.76% and 86.71%, respectively. The AE showed the best inhibitory effect of Eisenia bicyclis extracts (50 mg%) against trypsin (24.37%) and α-chymotrypsin (49.05%), respectively. These results suggest that Eisenia bicyclis extracted by AE can be used as a bioactive and functional material in the food industry.