An alternative peptone preparation using Hermetia illucens (Black soldier fly) hydrolysis: process optimization and performance evaluation

Background

Hermetia illucens (HI), commonly known as the black soldier fly, has been recognized for its prowess in resource utilization and environmental protection because of its ability to transform organic waste into animal feed for livestock, poultry, and aquaculture. However, the potential of the black soldier fly's high protein content for more than cheap feedstock is still largely unexplored.

Methods

This study innovatively explores the potential of H. illucens larvae (HIL) protein as a peptone substitute for microbial culture media. Four commercial proteases (alkaline protease, trypsin, trypsase, and papain) were explored to hydrolyze the defatted HIL, and the experimental conditions were optimized via response surface methodology experimental design. The hydrolysate of the defatted HIL was subsequently vacuum freeze-dried and deployed as a growth medium for three bacterial strains (Staphylococcus aureus, Bacillus subtilis, and Escherichia coli) to determine the growth kinetics between the HIL peptone and commercial peptone.

Results

The optimal conditions were 1.70% w/w complex enzyme (alkaline protease: trypsin at 1:1 ratio) at pH 7.0 and 54 °C for a duration of 4 h. Under these conditions, the hydrolysis of defatted HIL yielded 19.25% ±0.49%. A growth kinetic analysis showed no significant difference in growth parameters (μmax, Xmax, and λ) between the HIL peptone and commercial peptone, demonstrating that the HIL hydrolysate could serve as an effective, low-cost alternative to commercial peptone. This study introduces an innovative approach to HIL protein resource utilization, broadening its application beyond its current use in animal feed.

Effect of insect protein and protease on growth performance, blood profiles, fecal microflora and gas emission in growing pig

Two experiments were conducted to determine the effect of Hermetia illucens larvae (HIL) as protein and protease on growth performance, blood profiles, fecal microflora, and gas emission in growing pig. In experiment 1, the seventy-two crossbred growing pigs ([Landrace × Yorkshire] × Duroc) with an initial body weight (BW) of 27.98 ± 2.95 kg were randomly allotted to one of four dietary treatments (3 pigs per pen and 6 replicates pen per treatments). The experimental design was a 2 × 2 factorial arrangement of treatments evaluating two diets (Poultry offal diets and HIL diets) without or with supplementing protease. The poultry offal in basal diet has been replaced by HIL. In experiment 2, the four crossbred growing pigs ([Landrace × Yorkshire] × Duroc) with an initial BW of 28.2 ± 0.1 kg were individually accepted in stainless steel metabolism cages. The dietary treatments included: 1) PO- (PO-; poultry offal diet), 2) PO+ (PO- + 0.05% protease), 3) HIL- (3% PO of PO- diet was replacement 3% HIL), 4) HIL+ (HIL- + 0.05% protease). In experiment 1, From weeks 0 to 2, average daily gain (ADG) and feed efficiency (G:F) were significantly increased in the PO diet group compared with the HIL group. From weeks 2 to 4, ADG and G:F were higher for protease group than for non-protease group. At weeks 2 and 4, the PO diet group had lower blood urea nitrogen (BUN) levels than HIL diet group. In experiment 2, crude protein (CP) and nitrogen (N) retention were decreased by HIL diet at weeks 2 and 4. The fecal microflora and gas emission were not affected by HIL and protease. The HIL diet showed lower CP digestibility than PO diet and total essential amino acids digestibility tended to higher in PO diet than HIL diet. In summary, the present study revealed that replacement of the PO protein with the HIL protein and the additive of protease in growing pig diets during the overall experimental period had no negative effect.

Dietary Hermetia illucens Larvae Replacement Alleviates Diarrhea and Improves Intestinal Barrier Function in Weaned Piglets Challenged With Enterotoxigenic Escherichia coli K88

A high-quality protein substitute, Hermetia illucens (black soldier fly) larvae powder, is rich in protein and often used in animal feed. This study aimed to investigate the feasibility and optimal ratio of replacing fish meal with H. illucens larvae in weaned piglets and to demonstrate the effects on piglets' growth performance, intestinal microflora and immune performance. Forty-eight female weaned piglets were randomly classified into three groups. Each group consisted of eight pens (replicates), with two piglets per pen. Three groups containing different proportions of H. illucens larvae (0, 4, and 8%) were referred to as C, HI4, and HI8. We first designed a 28-day feeding experiment to detect growth performance; after that, the piglets were induced with oral gavage of enterotoxigenic Escherichia coli K88 (ETEC K88) and recording diarrhea on day 29 of the experiment. Samples were taken on the 32nd day to detect the effect of H. illucens larvae on the immune performance of the weaned piglets. H. illucens larvae replacement did not cause any obvious change in the growth performance nether in HI4 nor in HI8 of weaned piglets with 28 d feeding stage. H. illucens larvae could improve the intestinal health of weaned piglets by increasing the content of Lactobacillus and reducing the content of Streptococcus. Compared with C+K88 group, the diarrhea rate was attenuated for the H. illucens supplemented group. The integrity of ileum villi in HI4+K88 and HI8+K88 groups was better than that in C+K88 group, and the villi in C+K88 group were severely damaged. The expression of IL-10, Occludin and Claudin-3 in the intestinal mucosa of the HI4+K88 group and HI8+K88 group were significantly increased (P < 0.05), and the expression of TNF-α was significantly decreased (P < 0.05) compared with the C+K88 group. The results of immunoblotting also validated that the same ETEC K88 treatment of weaned piglets enhanced the expression of tight junction protein in the intestinal mucosa of the H. illucens addition group. ETEC-induced diarrhea will be reduced by the diet of weaned piglets containing H. illucens larvae, ameliorating the immune performance of piglets. Our results indicates that the optimal dosage of H. illucens replacement in weaned piglets is 4%.

Evaluation of the Antimicrobial Activity of an Extract of Lactobacillus casei-Infected Hermetia illucens Larvae Produced Using an Automatic Injection System

Simple Summary

In this investigation, an automatic mass-injection system was developed to produce an extract of Lactobacillus casei–infected Hermetia illucens larvae (HIL) at low cost. The extract produced was found to be a novel natural antibiotic candidate with a wide range of applications, especially in the food, animal feed, and medicinal industries.

Abstract

In the present study, we developed an automatic mass-injection system (AMIS) to produce an extract of infected H. illucens larvae (iHIL-E) and then evaluated antimicrobial peptide (AMP) expressions and assessed the antimicrobial activity of iHIL-E against various pathogens and Lactobacillus species. AMP gene expressions were assessed by real-time quantitative polymerase chain reaction (PCR) and the antimicrobial activities of iHIL-E were estimated using a radial diffusion assay and by determining minimal inhibitory concentrations. Results showed that the antimicrobial activity of HIL extract was effectively enhanced by L. casei infection and that the gene expressions of cecropin 3 and defensin 3 (antimicrobial peptides) were up-regulated. iHIL-E also prevented the growths of Enterococcus faecalis, Streptococcus mutans, and Candida vaginitis (MICs 200, 500, and 1000 µg/100 µL, respectively) and demonstrated high protease resistance. Moreover, the growths of methicillin-resistant Staphylococcus aureus, antibiotic-resistant Pseudomonas aeruginosa and AMP-resistant bacteria, Serratia marcescens, and Pseudomons tolaasii were significantly suppressed by iHIL-E. In addition, although iHIL completely cleared Salmonella species at concentrations of >200 µg/100 µL, Lactobacillus species were unaffected by iHIL at concentrations of <1000 µg/100 µL. The present investigation shows that the devised automatic mass injection system is effective for the mass production of the extract of infected HIL and that this extract is a novel, natural, protease-resistant, antibiotic candidate with broad-spectrum antibiotic activity.

Bioactive Compounds from Hermetia Illucens Larvae as Natural Ingredients for Cosmetic Application

Due to the sustainable organic matter bioconversion process used as substrate for its development, the Hermetia illucens (Linnaeus) larvae biomass is considered a source of compounds with high aggregate value and quite a promising market. The materials that can be extracted from H. illucens larvae have opened the door to a diverse new field of ingredients, mainly for the feed and food industry, but also with potential applicability in cosmetics. In this review we succinctly describe the larval development and rearing cycle, the main compounds identified from different types of extractions, their bioactivities and focus on possible applications in cosmetic products. A search was made in the databases PubMed, ScienceDirect and Web of Science with the terms ‘Hermetia illucens’, ‘bioactives’, ‘biochemical composition’ and ‘cosmetics ingredients’, which included 71 articles published since 1994.

Hermetia illucens larvae as a potential dietary protein source altered the microbiota and modulated mucosal immune status in the colon of finishing pigs

Background

Insects, such as Hermetia illucens larvae, are rich in chitin and proteins, and represent a suitable feed ingredient replacement for animals. However, little is known about the effect of administering H. illucens larvae on intestinal microbiota, bacterial metabolite profiles, and mucosal immune status in animals. This study aimed to investigate the effects of administering H. illucens larvae on colonic microbiota and bacterial metabolites production in finishing pigs. Seventy-two crossbred (Duroc × Landrace × Large White) female pigs (initial body weight, 76.0 ± 0.52 kg) were randomly allocated to three different dietary treatments: a control diet (Control group) and two diets corresponding to 4% (H1 group) and 8% (H2 group) H. illucens larvae inclusion levels, respectively. Each treatment consisted of eight pens (replicates), with three pigs per pen. After 46 days of feeding, eight pigs per treatment (n = 8) were slaughtered, and the colonic digesta and mucosa were collected for microbial composition and microbial fermentation products, and genes expression analyses.

Results

The results showed that the H1 diet significantly increased the abundance of Lactobacillus, Pseudobutyrivibrio, Roseburia, and Faecalibacterium compared with those in the control group (P < 0.05), with a decrease in the abundance of Streptococcus. The numbers of Lactobacillus, Roseburia, and Clostridium cluster XIVa were significantly greater in the H1 group than in the control group (P < 0.05). Meanwhile, H2 diet increased the number of Clostridium cluster XIVa compared with the control group (P < 0.05). For colonic metabolites, total short chain fatty acids, butyrate, and isobutyrate concentrations were significantly higher in the H1 group than those in the control group (P < 0.05); the H1 treatment caused a striking decrease in protein fermentation compared with the control group, as the concentrations of total amines, cadaverine, tryptamine, phenol, p-cresol, and skatole were significantly lower (P < 0.05). Additionally, H2 diet also increased butyrate concentration compared with control group (P < 0.05), while decreased the concentrations of phenol, p-cresol, and skatole (P < 0.05). Pigs in the H1 group down-regulated the expression of TLR-4 and pro-inflammatory cytokines (IFN-γ) compared with pigs in the control group (P < 0.05), and up-regulated anti-inflammatory cytokine (IL-10) and intestinal barrier genes (ZO-1, occludin, and mucin-1). H2 diet up-regulated the expression of ZO-1 compared with control group (P < 0.05). Furthermore, the changes in the colonic mucosal gene expression were associated with changes in the bacterial composition and their metabolites.

Conclusions

Collectively, dietary inclusion of Hermetia illucens larvae may enhance mucosal immune homeostasis of pigs via altering bacterial composition and their metabolites. These findings provide a new perspective on insect meal as a sustainable protein source rich in nutrient ingredients for swine.

Electronic supplementary material

The online version of this article (10.1186/s40104-019-0358-1) contains supplementary material, which is available to authorized users.

Use of Hermetia illucens larvae as a dietary protein source: Effects on growth performance, carcass traits, and meat quality in finishing pigs

This study investigated the effects of feeding Hermetia illucens larvae (0, 4, and 8%; HI0, HI4, and HI8 groups, respectively) on growth performance, carcass traits, and meat quality of finishing pigs. Results showed that the HI4 diet increased (P < .05) final body weight and average daily gain and decreased (P < .05) feed to gain ratio compared with HI0 and HI8 group. HI4 and HI8 diets increased (P < .05) loin-eye area, marbling scores, and inosine monophosphate content of longissimus thoracis (LT) compared with HI0 diet. The intramuscular fat content was greater (P < .05) in HI4 group than in the HI0 group. Furthermore, HI4 diet up-regulated (P < .05) lipogenic genes and MyHC-IIa mRNA levels in LT compared with HI0 diet. Our results indicated that dietary inclusion of H. illucens larvae has a beneficial impact on growth performance and meat quality, and the underlying mechanism may be due to the altered lipogenic potential induced by H. illucens larvae.