Determining the Black Soldier fly larvae performance for plant-based food waste reduction and the effect on Biomass yield

Trilogy of comprehensive treatment of kitchen waste by bacteria-microalgae-fungi combined system: Pretreatment, water purification and resource utilization, and biomass harvesting

Given its profound disservice, a bacteria-microalgae-fungi combined system was designed to treat kitchen waste. Firstly, a new type of microbial agent homemade compound microorganisms (HCM) (composed of Serratia marcescens, Bacillus subtilis and other 11 strains) with relatively high bio-security were developed for pretreating kitchen waste, and HCM efficiently degraded 85.2 % cellulose, 94.3 % starch, and 59.0 % oil. HCM also accomplished brilliantly the initial nutrients purification and liquefaction conversion of kitchen waste. Under mono-culture mode (fungi and microalgae were inoculated separately in the pre - and post-stages) and co-culture mode (fungi and microalgae were inoculated simultaneously in the early stage), microalgae-fungi consortia were then applied for further water purification and resource utilization of kitchen waste liquefied liquid (KWLL) produced in the pretreatment stage. Two kinds of microalgae-fungi consortia (Chlorella sp. HQ and Chlorella sp. MHQ2 form consortia with pellet-forming fungi Aspergillus niger HW8-1, respectively) removed 79.5-83.0 % chemical oxygen demand (COD), 44.0-56.5 % total nitrogen (TN), 90.3-96.4 % total phosphorus (TP), and 64.9-71.0 % NH4+-N of KWLL. What's more, the microalgae-fungi consortia constructed in this study accumulated abundant high-value substances at the same time of efficiently purifying KWLL. Finally, in the biomass harvesting stage, pellet-forming fungi efficiently harvested 81.9-82.1 % of microalgal biomass in a low-cost manner through exopolysaccharides adhesion, surface proteins interaction and charge neutralization. Compared with conventional microalgae-bacteria symbiosis system, the constructed bacteria-microalgae-fungi new-type combined system achieves the triple purpose of efficient purification, resource utilization, and biomass recovery on raw kitchen waste through the trilogy strategy, providing momentous technical references and more treatment systems selection for future kitchen waste treatment.

Exploring the role of the microbiome of the H. illucens (black soldier fly) for microbial synergy in optimizing black soldier fly rearing and subsequent applications

The symbiotic microbiome in the insect's gut is vital to the host insect's development, improvement of health, resistance to disease, and adaptability to the environment. The black soldier fly (BSF) can convert organic substrates into a protein- and fat-rich biomass that is viable for various applications. With the support of a selective microbiome, BSF can digest and recycle different organic waste, reduce the harmful effects of improper disposal, and transform low-value side streams into valuable resources. Molecular and systems-level investigations on the harbored microbial populations may uncover new biocatalysts for organic waste degradation. This article discusses and summarizes the efforts taken toward characterizing the BSF microbiota and analyzing its substrate-dependent shifts. In addition, the review discusses the dynamic insect-microbe relationship from the functional point of view and focuses on how understanding this symbiosis can lead to alternative applications for BSF. Valorization strategies can include manipulating the microbiota to optimize insect growth and biomass production, as well as exploiting the role of BSF microbiota to discover new bioactive compounds based on BSF immunity. Optimizing the BSF application in industrial setup and exploiting its gut microbiota for innovative biotechnological applications are potential developments that could emerge in the coming decade.

A metanalysis to evaluate the effects of substrate sources on the nutritional performance of black soldier fly larvae: implications for sustainable poultry feed

This meta-analysis presents an evaluation of substrate sources and their impact on the growth performance of black soldier fly (BSF) larva. The database, compiled from Google Scholar, PubMed, and Science Direct, focuses on data concerning substrate sources, environmental conditions, and the performance parameters of BSF. Seven types of substrates were analyzed, including Feed Waste, Manure, Fruits, Mix, Animal Source, Fermentation Residue, and Food Waste. The Feed Waste group demonstrated the highest DM content, while the highest CP content was found in the Animal Source group. Higher CP and DM content were found in larva meal from Fermentation Residues and Feed Waste diets, respectively. Higher survival rates were observed in BSF larvae fed on Feed Waste, Fermentation Residues, Food Waste, Fruits, Mix, and Manure substrates compared to Vegetable and Animal Source substrates. Fresh larval weight was lower when Manure was used as a feed substrate than in the Animal Source, Feed Waste, and Vegetable substrates. The prepupal Wet Weight was highest in BSF larvae fed on Animal Source, surpassing those fed on Fermentation Residue, Manure, and Vegetable substrates. Substrate CP content exhibited a positive relationship with fresh larva weight, prepupal wet weight, dry larval weight; larval length, mortality until prepupal, protein conversion, feed conversion ratio, food consumption, substrate reduction rate bioconversion ratio, waste reduction index, and efficiency conversion of digested feed in BSF larva. In conclusion, our findings underline that the source and composition of substrates are correlated to the nutritional composition and conversion efficiency of BSF larva meal.

Enhancing food waste reduction efficiency and high-value biomass production in Hermetia illucens rearing through bioaugmentation with gut bacterial agent

The black soldier fly (BSF) rearing technology has been a promising bioconversion method for food waste (FW) disposal. However, when used independently, it currently only achieves low efficiency and biomass transformation rates (BTR). This study screened and identified two strains of gut beneficial bacteria, Bacillus cereus and Bacterium YC-LK-LKJ45. The efficiency of a complex culture formulated by these strains was investigated, focusing on enhancing FW reduction and high-value biomass production during the rearing of BSF larvae. The coculture agent group (G1-10%, with two strains in 1:1 volume ratio at a 10 % dosage) exhibited higher larval yield (627.67 g·kg-1), BTR (47.90 %), FW reduction efficiency (80.67 %), and total protein and fat yield (261.99 g·kg-1and 46.24 g·kg-1) compared to the control and the monoculture agent group (which added a single gut beneficial bacteria agent, either Bacillus cereus or Bacterium YC-LK-LKJ45). The bacterial agent altered the richness and diversity of the gut microbial community of BSF, increasing the relative abundance of beneficial bacteria such as Bacillus, Oceano bacillus, and Akkermansia, while decreasing pathogenic bacteria, such as Acinetobacter and Escherichia-Shigella. Structural equation model quantification revealed that α-diversity (λ = 0.897, p < 0.001) and BTR (λ = 0.747, p < 0.001) are crucial drivers for enhancing high-value biomass during bioaugmentation rearing. This investigation provides a theoretical framework for the effective management of food waste using BSF, enhancing its decomposition and transformation into higher-value biomass.

Effects of straw addition on the physicochemical and microbial features of black soldier fly larvae frass derived from fish meat and bone meal

Black soldier fly larvae (BSFL) hold great promise for sustainable management of meat and bone meal (MBM), a kind of organic waste. Harvested BSFL frass can be used as soil amendment or organic fertilizer. This study evaluated the quality and microbial profile in the frass of BSFL, fed with fish MBM containing 0% (CK), 1% (T1), 2% (T2) and 3% (T3) of rice straw. Results suggested straw addition into fish MBM had no significant impacts on BSFL weight; however, straw addition remarkably affected waste reduction and conversion efficiency, as well as physicochemical properties including electric conductivity, organic matter (OM) and total phosphorus contents in frass. Fourier transform infrared analysis indicated that increasing levels of cellulose and lignin might not be fully degraded or transformed by BSFL when more straw was introduced into substrates. Straw addition had hardly significant influences on microbial richness or evenness in BSFL frass, only T3 treatment remarkably elevated the phylogenetic diversity value more than the control. Bacteroidetes, Proteobacteria, Actinobacteria and Firmicutes were the most dominant phyla. Genera Myroides, Acinetobacter and Paenochrobactrum maintained high abundances in all frass samples. Elements including OM, pH and Na were key factors in shaping the microbiological characteristics of BSFL frass. Our findings helped to understand the effects of fish MBM waste manipulation on BSFL frass qualities and contributed to the further application of BSFL frass.

Black soldier fly pretreatment promotes humification and phosphorus activation during food waste composting

Black soldier fly (BSF) and thermophilic composting (TC) treatments are commonly adopted to manage food waste. In this study, 30 days of TC of food waste following seven days BSF pretreatment (BC) was compared to 37 days of TC of food waste (TC, the control). Fluorescence spectrum and 16S rRNA high-throughput sequencing analysis were used to compare the BC and TC treatments. Results showed that BC could decrease protein-like substances and increase humus substances more quickly, and that the humification index of compost products was 106.8% higher than that of TC, suggesting that the humification process was accelerated by BSF pretreatment resulting in a 21.6% shorter maturity time. Meanwhile, the concentrations of total and available phosphorus rose from 7.2 and 3.3 g kg-1 to 44.2 and 5.5 g kg-1, respectively, which were 90.5% and 118.8% higher in compost products from BC as compared to those in TC. Furthermore, BC had higher richness and diversity of humus synthesis and phosphate-solubilizing bacteria (PSB), with Nocardiopsis (53.8%) and Pseudomonas (47.0%) being the dominant PSB. Correlation analysis demonstrated that the introduction of BSF gut bacteria contributed to the effectiveness of related functional bacteria, resulting in a rapid humification process and phosphorus activation. Our findings advance understanding of the humification process and provide novel perspectives on food waste management.

Quality Characteristics of Black Soldier Flies Produced by Different Substrates

Black soldier fly (BSF; Hermetia illucens) has a high capacity for amino acids and fatty acid accumulation. This study was conducted to assess the effectiveness of tofu by-products, food waste, and vegetables for BSF growth and conversion efficiency. BSFs under tofu by-product treatments showed the greatest weight at d 12 and the harvest period. Moreover, BSF larval weight was greater in the food waste treatment compared with the vegetable treatment at d 12 and harvest. The larva yield result was greater in the vegetable treatment compared with the tofu by-product. The bioconversion rate was higher in the tofu by-product treatment compared with the food waste and vegetable treatments. The protein conversion rate and lipid conversion rate were the highest in the vegetable treatment. The protein yield and lipid yield were greatest in the tofu by-product treatment. The lauric acid content was increased in BSFs fed tofu by-products compared with the food waste treatment. The concentration of C16:1 was the highest in the tofu by-product treatment. The content of oleic acid and α-linolenic acid was higher in BSFs fed tofu by-products compared with the vegetable treatment. In conclusion, the tofu by-products show benefits for larval growth and nutrient accumulation, which can improve larval quality for livestock feed ingredients.

Determination of black soldier fly larvae performance for oil palm based waste reduction and biomass conversion

Oil palm biomass, such as empty fruit bunches and palm kernel meal, has low digestibility. Thus, a suitable bioreactor is urgently needed to efficiently convert oil palm biomass into high-value products. The polyphagous black soldier fly (BSF, Hermetia illucens) has gained global attention for its role in biomass conversion. However, there is scarce information on the ability of the BSF to sustainably manage highly lignocellulosic matter, such as oil palm empty fruit bunches (OPEFB). Therefore, this study aimed to investigate the performance of the black soldier fly larvae (BSFL) in oil palm biomass management. Several formulations were fed to the BSFL five days after hatching (DAH), and the effects on oil palm biomass-based substrate waste reduction and biomass conversion were analyzed. Furthermore, the resulting growth parameters correlating to the treatments were evaluated, including feed conversion rate (FCR), survival rates, and developmental rates. The most optimal results were obtained by mixing 50% of palm kernel meal (PKM) with 50% of coarse oil palm empty fruit bunches (OPEFB), resulting in an FCR of 3.98 ± 0.08 and a survival rate of 87% ± 4.16. Moreover, this treatment is a promising method for waste reduction (11.7% ± 6.76), with a bioconversion efficiency (corrected for residue) of 71.5% ± 1.12. In conclusion, the study findings indicate that incorporating PKM into OPEFB substrate can substantially alter BSFL growth, reduce oil palm waste, and optimize biomass conversion.

Bioconversion of fruit waste and sewage sludge mixtures by black soldier fly (Diptera: Stratiomyidae) larvae

Bioconversion of fruit waste (FW) and sewage sludge (SS) sludge mixtures into valuable products was investigated using black soldier fly (Hermetia illucens) larvae (BSFL) under a lab-scale trial. For that, five different setups of FW and SS mixtures (100FW; 100SS; 70SS+30FW; 50SS+50FW; 70FW+30SS) were prepared and changes in larval biomass, feed loss, and residual waste physicochemical properties were estimated until the emergence of fly in all waste mixtures. BSFL caused a significant decrease in total organic carbon (11.71-34.79%) and carbon-to-nitrogen ratio (C/N ratio) while the increase in total nitrogen (8.35-123.30%), total phosphorus (17.02-143.36%), and total potassium (19.40-48.87%) contents in the feedstock. The germination index and C/N ratio of frass were below the standards decided for manure quality in a few setups suggesting the non-stability of frass for agronomic applications due to the short duration (20 d) of composting. Larval biomass yield, feed conversion ratio and nutrient mineralization were found to be higher in 50SS+50FW and 70FW+30SS feedstock combinations suggesting their suitability as ideal feedstock for optimal BSFL cultivation. The impact of toxic substances in sewage on BSFL survival, growth and waste stabilization processes, and frass metal enrichment could be investigated in future studies.

Effect of Adding De-Oiled Kitchen Water on the Bioconversion of Kitchen Waste Treatment Residue by Black Soldier Fly Larvae

With the continuous development of society, the output of kitchen waste (KW) is fast increasing. De-oiled kitchen water (DKW) and kitchen waste treatment residue (KWTR), two main by-products of the KW treatment industry, are produced accordingly on a large scale. The need to develop an effective technique for the utilization of DKW and KWTR is attracting wide attention. In the present study, black soldier fly larvae (BSFL) were employed as a biological treatment method to treat KWTR with the addition of DKW. The influence of DKW (0-140 mL) on the efficiency of BSFL treatment evaluated by the growth and development of BSFL, the body composition of BSFL, the nutrient content of bioconversion residue (BR), and the bioconversion efficiency of KWTR, was investigated. The results showed that the growth and development of BSFL, the body composition of BSFL, and the conversion rate of KWTR were initially promoted and then inhibited with the addition of DKW. Notably, the amount of DKW added in the T110 group was the most suitable for the growth of BSFL and the accumulation of body composition. Compared with the blank comparison group, the content of crude protein (CP), crude ash (CA), salinity, total phosphorus (TP), and dry matter (DM) of BSFL in the T110 group increased by 3.54%, 6.85%, 0.98%, 0.07% and 2.98%, respectively. However, the addition of DKW could steadily increase the nutrient content of BR, with the highest amount at 140 mL DKW. Following DKW addition, the contents of CP, ether extract (EE), crude fiber (CF), organic matter (OM), total nitrogen (TN), TP, and total potassium (TK) were increased by 4.56%, 3.63%, 10.53%, 5.14%, 0.73%, 0.75%, and 0.52%, respectively, compared with those of the blank comparison group. The study showed that DKW could be used as a nutrient additive in the bioconversion process of KWTR by BSFL, which provided a new method for the resource utilization of DKW.

Health risk assessment of mercury in Nile tilapia (Oreochromis niloticus) fed housefly maggots

The bioaccumulation of total mercury (THg) and methylmercury (MeHg) by housefly maggots (HM) during the conversion of food waste (vegetables and meat (VM) and rice waste) under various waste feed ratios were investigated. Subsequently, Nile tilapia (Oreochromis niloticus) were fed with the commercial feed, commercial dried HM, dried HM, and fresh HM, followed by a human health risk assessment of Hg via fish consumption. The THg concentrations of HM fed with food waste ranged from 39.5 to 100 μg kg^-1 ww. Concentrations of MeHg in the maggots fed with 100 % vegetables and meat (VM) waste (13.7 ± 1.12 μg kg^-1 ww) was significantly higher than that fed with other mixed ratios of rice waste and VM waste (p<0.05). Concentrations of MeHg were positively correlated with the weight and lipid content of houseflies (p<0.05). THg and MeHg concentrations in tilapia fed with the converted HM (dried and fresh HM) were 22.5 ± 6.50 μg kg^-1 ww and 2.43 ± 0.36 μg kg^-1 ww, respectively. There was no significant difference in MeHg between tilapia fed the four experiment diets (p>0.05). Health risk assessment results indicated that mercury in tilapia fed the food waste-grown HM did not pose potential health risks to humans (target hazard quotient < 1). In conclusion, HM could convert food waste into high-quality and safe fish feeds for cultivating tilapia.

Transformation of food waste to source of antimicrobial proteins by black soldier fly larvae for defense against marine Vibrio parahaemolyticus

Insect biorefinery by black soldier fly larvae (BSFL), Hermetia illucens, has emerged as an innovative technique for the valorization of food waste. However, despite BSFL being an attractive natural source of antimicrobial proteins (AMPs), there is a scarcity of research on the antimicrobial activity and transcriptome expression of AMPs derived from BSFL following waste treatment. In the present study, food waste treatment was performed by BSFL with a substrate C/N ratio ranging from 21:1 to 10:1, marine Vibrio parahaemolyticus (VP) was selected as the model aquaculture pathogen, the antimicrobial activities of AMPs in vitro and zebrafish in vivo were examined, and the molecular mechanism of the C/N-dependent AMP difference was expounded. Findings were made that the AMP extract of C/N16:1 resulted in relatively higher antimicrobial activity in vitro than that of other C/Ns. Further, the AMPs of C/N16:1 exhibited a promising in vivo defense effect for elevating the 96-h survival rate of zebrafish from 0% to 39% after VP infection, comparable to the animal antibiotic sulfamethoxidine. The results of transcriptome analysis reveal that lysozymes were the highest expressed components in the AMP gene family. The C/N16:1 BSFL significantly up-regulated 12 out of 51 lysozyme genes compared with C/N21:1, which likely contributed to the improvement of AMP antimicrobial activity. Further, C/N16:1 significantly up-regulated the expression of lysozyme, glycosyl hydrolase and muscle protein genes compared with C/N21:1, which likely enhanced the defense ability of the immune system, the utilization of the starch-like substrate, and the mobility of the larvae, thereby facilitating the larval transformation and AMP production. Overall, such results indicate that waste C/N ratio interacted with the activity and expression of BSFL AMPs through transcriptome regulation, and the BSFL AMPs derived from food waste could be used for the defense against marine pathogens to support the sustainable development of aquaculture.

Food Waste Management Employing UV-Induced Black Soldier Flies: Metabolomic Analysis of Bioactive Components, Antioxidant Properties, and Antibacterial Potential

Food waste, as a major part of municipal solid waste, has been increasingly generated worldwide. Efficient and feasible utilization of this waste material for biomanufacturing is crucial to improving economic and environmental sustainability. In the present study, black soldier flies (BSF) larvae were used as carriers to treat and upcycle food waste. Larvae of the BSF were incubated with UV light for 10, 20, and 30 min at a wavelength of 257.3 nm and an intensity of 8 W. The food waste utilization efficiency, antioxidant assays, antibacterial activity, and bioactive metabolites without and with UV treatment were determined and compared. Results showed that the BSF larvae feed utilization rate was around 75.6%, 77.7%, and 71.2% after UV treatment for 10, 20, and 30 min respectively, contrasting with the non-UV induced group (73.7%). In addition, it was perceived that the UV exposure enhanced antioxidant and antimicrobial properties of BSF extracts, and the maximum values were observed after 20 min UV induction time. Moreover, UV-induced BSF extracts showed an improved metabolic profile than the control group, with a change in the amino acids, peptides, organic acids, lipids, organic oxides, and other derivatives. This change in metabolomics profile boosted environmental signaling, degradation of starch, amino acids, sugars, and peptide metabolism. It was concluded that the bioconversion of food wastes using UV-induced BSF larvae can enhance the generation of a variety of functional proteins and bioactive compounds with potent antioxidant and antimicrobial activity. However, more studies are required to exploit the efficiency of UV treatment in improving BSF’s potential for upcycling of food wastes.

Effect of Different Organic Substrates on Selected Life History Traits and Nutritional Composition of Black Soldier fly (Hermetia illucens)

Black soldier fly (Hermetia illucens L. [Diptera: Stratiomyidae]) has gained huge popularity in different industrial and commercial sectors because of its excellent potential to treat organic waste and high biomass production. As the industrial application of BSF is expanding at accelerated rates, there is a need to optimize its mass scale production where the organic substrates play a very crucial role in optimal growth and development. The present study deals with the investigation of different life history attributes of BSF such as larval and adult weights, survival, pupation rate, and the development time as the function of different organic substrates [fruits and vegetable mix (T1); wheat bran, soy, and corn meal mix (T2); and the dairy manure (T3)]. The larval, pupal, and adult weights differed across all three treatments (P < 0.05). There was no significant difference in the survival rate of larvae among T1 and T2 however, T3 differed significantly from T1 and T2. Likewise, the pupation rate and the development time differed significantly between the three treatments. Results indicated that the BSF development was least in dairy manure treatment and therefore, higher percent mortality and higher development time were observed. However, to deal with the problems of waste management and treatment, BSF larvae can be successfully employed for the treatment of any type of waste since it showed significant treatment efficiencies.

A Modified Lysimeter Study for Phyto-Treatment of Moderately Saline Wastewater Using Plant-Derived Filter Bedding Materials

The present study focuses on determining the phyto-treatment efficiency for treatment of moderately saline wastewater using organic raw materials, such as rice husk, coconut husk, rice straw, and charcoal. The moderately saline wastewater with total dissolved solids (TDS) concentration up to 6143.33 ± 5.77 mg/L was applied to the lysimeters at the rate of 200 m3 ha-1 day-1 in five different lysimeter treatments planted with Eucalyptus camaldulensis (T1, T2, T3, T4, and T5). T1 was a control without any filter bedding material, whereas rice straw, rice husk, coconut husk, and charcoal were used as filter bedding materials in the T2, T3, T4, and T5 treatment systems, respectively. Each treatment showed significant treatment efficiency wherein T3 had the highest removal efficiency of 76.21% followed by T4 (67.57%), T5 (65.18%), T2 (46.46%), and T1 (45.5%). T3 and T4 also showed higher salt accumulation, such as sodium (Na) and potassium (K). Further, the pollution load in terms of TDS and chemical and biological oxygen demand significantly reduced from leachate in the T3 and T4 treatments in comparison with other treatments. Parameters of the soil, such as electrical conductivity, exchangeable sodium percentage, and cation exchange capacity did not show values corresponding to high salinity or sodic soils, and therefore, no adverse impact on soil was observed in the present study. Also, Eucalyptus camaldulensis plant species showed good response to wastewater treatment in terms of growth parameters, such as root/shoot weight and nitrogen, phosphorus, and potassium (NPK) uptake, plant height, biomass, and chlorophyll content. Root and shoot dry weight were in the order T3 (51.2 and 44.6 g)>T4 (49.3 and 43.5 g) > T5 (47.6 and 40.5 g) > T2 (46.9 and 38.2 g) > T1 (45.6 and 37.1 g). Likewise, the total chlorophyll content was highest in T3 (12.6 μg/g) followed by T4 (12.3 μg/g), T5 (11.9 μg/g), T2 (11.5 μg/g), and the control, that is, T1 (11.0 μg/g). However, the most promising results were obtained for T3 and T4 treatments in comparison with the control (T1), which implies that, among all organic raw materials, coconut and rice husks showed the highest potential for salt accumulation and thereby wastewater treatment. Conclusively, the findings of the study suggest that organic raw material-based amendments are useful in managing the high salts levels in both plants and leachates.

Organic waste amendments for restoration of physicochemical and biological productivity of mine spoil dump for sustainable development

Rehabilitation of degraded lands due to mining and other activities requires rebuilding of the appropriate soil structure and microbial integrity. Organic wastes, in particular plant-based materials, play a vital role in restoration of degraded land when used as amendments for topsoil integrated with microbe-assisted phytoremediation. In this present study, a biotechnological approach using the combination of organic waste amendments, i.e., ETP (effluent treatment plant), sludge from sugarcane and paper industry, and the press mud respectively along with microbial and fungal inoculum isolated from the soil rhizosphere have been applied to study the influence on fertility and productivity of mine spoil from manganese and coal dumps. The organic amendments applied as 100-ton ha^-1 and application of biofertilizers boosted the survival of plants such as Tectona grandis (Teak), Dalbergia sisso (North Indian rosewood), Phyllanthus emblica (Indian gooseberry), Gmelina arborea (Gamhar), and Acacia auriculiformis (Earpod wattle) from 80 to 100% with robust growth and development during the short span of 25 years. The physicochemical attributes of soil and the microbial count also increased significantly. The pH of mine soil dumps slightly shifted toward alkaline conditions (7.4 to 7.8) whereas bulk density, porosity, and the water holding capacity were greatly improved. Other than this, the nutrient status of mine dump soil and the plants such as available nitrogen, phosphorus, potassium and the organic carbon content in soil were improvised to a greater extent simultaneously decreasing the available manganese concentration. The findings of the study assure a better land reclamation and restoration approach.