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Gorrens E, Lecocq A, De Smet J. The Use of Probiotics during Rearing of Hermetia illucens: Potential, Caveats, and Knowledge Gaps. Microorganisms 2023; 11:microorganisms11020245. [PMID: 36838211 PMCID: PMC9960648 DOI: 10.3390/microorganisms11020245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/10/2023] [Accepted: 01/16/2023] [Indexed: 01/21/2023] Open
Abstract
Given the novelty of the industrial production of the edible insects sector, research has primarily focused on the zootechnical performances of black soldier fly larvae (BSFL) in response to different substrates and rearing conditions as a basis to optimize yield and quality. However recently, research has started to focus more on the associated microbes in the larval digestive system and their substrates and the effect of manipulating the composition of these communities on insect performance as a form of microbiome engineering. Here we present an overview of the existing literature on the use of microorganisms during rearing of the BSFL to optimize the productivity of this insect. These studies have had variable outcomes and potential explanations for this variation are offered to inspire future research that might lead to a better success rate for microbiome engineering in BSFL.
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Affiliation(s)
- Ellen Gorrens
- Research Group for Insect Production and Processing, Department of Microbial and Molecular Systems (M²S), KU Leuven, 2440 Geel, Belgium
| | - Antoine Lecocq
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg, Denmark
| | - Jeroen De Smet
- Research Group for Insect Production and Processing, Department of Microbial and Molecular Systems (M²S), KU Leuven, 2440 Geel, Belgium
- Correspondence:
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Gorrens E, Van Looveren N, Van Moll L, Vandeweyer D, Lachi D, De Smet J, Van Campenhout L. Staphylococcus aureus in Substrates for Black Soldier Fly Larvae (Hermetia illucens) and Its Dynamics during Rearing. Microbiol Spectr 2021; 9:e0218321. [PMID: 34937197 PMCID: PMC8694120 DOI: 10.1128/spectrum.02183-21] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 11/22/2021] [Indexed: 11/29/2022] Open
Abstract
Black soldier fly larvae (BSFL; Hermetia illucens) are promising insects for the conversion of organic waste streams into valuable biomolecules. Such waste streams can contain foodborne pathogens. To assess this risk factor, this study evaluated the presence of Staphylococcus aureus in waste streams as a substrate ingredient for BSFL production as well as in the rearing process. First, the general microbiological quality and the occurrence of S. aureus were investigated for different waste streams. Staphylococcus aureus was abundantly present. Control of pH and water activity should avoid pathogens, which cannot grow in single-substrate ingredients, redeveloping when mixing streams for optimal substrate conditions for BSFL production. Next, it was investigated whether S. aureus present in the substrate was ingested and/or eradicated by BSFL. In inoculation trials, with S. aureus added to chicken feed as the substrate at 3 or 7 log CFU/g, the larvae showed a reducing effect on S. aureus. After 6 days, S. aureus counts were below the detection limit (2.0 log CFU/g) in all larvae samples and decreased in the substrate to <2.0 and <3.1 log CFU/g for inoculation levels of 3 and 7 log CFU/g, respectively. While this is promising, it is still recommended to monitor and control this pathogen in BSFL rearing. Intriguingly, screening of antimicrobial activity of dominant microorganisms associated with BSFL showed a clear activity of Trichosporon isolates against S. aureus. Future research should explore whether Trichosporon, which is frequently observed in BSFL, plays a role in controlling specific microorganisms, such as S. aureus. IMPORTANCE Given the increasing need for (more sustainable) methods to upcycle organic waste streams, the interest to rear insects, like black soldier fly larvae (BSFL), on such streams is increasing. This study reveals that S. aureus is abundantly present in such waste streams, which might be a point of attention for insect producers. At the same time, it reveals that when S. aureus was inoculated in chicken feed as the substrate, it was not detected in the larvae and was reduced in the substrate after 6 days. Future inoculation trials should investigate whether this reduction is substrate dependent or not. Toward the future, the role of the BSFL microbiota in controlling intestinal bacterial community homeostasis should be explored, because one of the dominant microorganisms associated with BSFL, Trichosporon spp., showed clear activity against S. aureus.
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Affiliation(s)
- E. Gorrens
- Department of Microbial and Molecular Systems (M2S), Research Group for Insect Production and Processing, KU Leuven, Geel Campus, Geel, Belgium
- Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
| | - N. Van Looveren
- Department of Microbial and Molecular Systems (M2S), Research Group for Insect Production and Processing, KU Leuven, Geel Campus, Geel, Belgium
- Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
| | - L. Van Moll
- Department of Microbial and Molecular Systems (M2S), Research Group for Insect Production and Processing, KU Leuven, Geel Campus, Geel, Belgium
- Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
- Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, Laboratory for Microbiology, Parasitology and Hygiene (LMPH), University of Antwerp, Wilrijk, Belgium
| | - D. Vandeweyer
- Department of Microbial and Molecular Systems (M2S), Research Group for Insect Production and Processing, KU Leuven, Geel Campus, Geel, Belgium
- Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
| | - D. Lachi
- Department of Microbial and Molecular Systems (M2S), Research Group for Insect Production and Processing, KU Leuven, Geel Campus, Geel, Belgium
- Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
| | - J. De Smet
- Department of Microbial and Molecular Systems (M2S), Research Group for Insect Production and Processing, KU Leuven, Geel Campus, Geel, Belgium
- Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
| | - L. Van Campenhout
- Department of Microbial and Molecular Systems (M2S), Research Group for Insect Production and Processing, KU Leuven, Geel Campus, Geel, Belgium
- Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
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Gorrens E, Van Moll L, Frooninckx L, De Smet J, Van Campenhout L. Isolation and Identification of Dominant Bacteria From Black Soldier Fly Larvae ( Hermetia illucens) Envisaging Practical Applications. Front Microbiol 2021; 12:665546. [PMID: 34054771 PMCID: PMC8155639 DOI: 10.3389/fmicb.2021.665546] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/15/2021] [Indexed: 11/13/2022] Open
Abstract
This study aimed to establish a representative strain collection of dominant aerobic bacteria from black soldier fly larvae (Hermetia illucens, BSFL). The larvae were fed either chicken feed or fiber-rich substrates to obtain a collection of BSFL-associated microorganisms. Via an approach based on only considering the highest serial dilutions of BSFL extract (to select for the most abundant strains), a total of 172 bacteria were isolated. Identification of these isolates revealed that all bacteria belonged to either the Proteobacteria (66.3%), the Firmicutes (30.2%), the Bacteroidetes (2.9%) or the Actinobacteria (0.6%). Twelve genera were collected, with the most abundantly present ones (i.e., minimally present in at least three rearing cycles) being Enterococcus (29.1%), Escherichia (22.1%), Klebsiella (19.8%), Providencia (11.6%), Enterobacter (7.6%), and Morganella (4.1%). Our collection of dominant bacteria reflects largely the bacterial profiles of BSFL already described in literature with respect to the most important phyla and genera in the gut, but some differences can be noticed depending on substrate, biotic and abiotic factors. Furthermore, this bacterial collection will be the starting point to improve in vitro digestion models for BSFL, to develop mock communities and to find symbionts that can be added during rearing cycles to enhance the larval performances, after functional characterization of the isolates, for instance with respect to enzymatic potential.
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Affiliation(s)
- Ellen Gorrens
- Department of Microbial and Molecular Systems (M2S), Lab4Food, KU Leuven, Geel, Belgium.,Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
| | - Laurence Van Moll
- Department of Microbial and Molecular Systems (M2S), Lab4Food, KU Leuven, Geel, Belgium.,Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium.,Laboratory for Microbiology, Parasitology and Hygiene (LMPH), Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Antwerp, Belgium
| | - Lotte Frooninckx
- Thomas More University of Applied Sciences, RADIUS, Geel, Belgium
| | - Jeroen De Smet
- Department of Microbial and Molecular Systems (M2S), Lab4Food, KU Leuven, Geel, Belgium.,Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
| | - Leen Van Campenhout
- Department of Microbial and Molecular Systems (M2S), Lab4Food, KU Leuven, Geel, Belgium.,Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
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Pot S, De Tender C, Ommeslag S, Delcour I, Ceusters J, Gorrens E, Debode J, Vandecasteele B, Vancampenhout K. Understanding the Shift in the Microbiome of Composts That Are Optimized for a Better Fit-for-Purpose in Growing Media. Front Microbiol 2021; 12:643679. [PMID: 33897654 PMCID: PMC8059793 DOI: 10.3389/fmicb.2021.643679] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/15/2021] [Indexed: 12/13/2022] Open
Abstract
Three characteristics are considered key for optimal use of composts in growing media: maturity, pH and organic matter content. Maturation is a critical step in the processing of composts contributing to compost quality. Blending of composts with chopped heath biomass, sieving out the larger fraction of composts and acidification of composts by adding elemental sulfur may be used either to increase organic matter content or to reduce pH for a better fit in growing media. While several studies have shown the effectiveness of these treatments to improve the use of composts in growing media, the effect of these treatments on the compost microbiome has merely been assessed before. In the present study, five immature composts were allowed to mature, and were subsequently acidified, blended or sieved. Bacterial and fungal communities of the composts were characterized and quantified using 16S rRNA and ITS2 gene metabarcoding and phospholipid fatty acid analysis. Metabolic biodiversity and activity were analyzed using Biolog EcoPlates. Compost batch was shown to be more important than maturation or optimization treatments to determine the compost microbiome. Compost maturation increased microbial diversity and favored beneficial microorganisms, which may be positive for the use of composts in growing media. Blending of composts increased microbial diversity, metabolic diversity, and metabolic activity, which may have a positive effect in growing media. Blending may be used to modify the microbiome to a certain degree in order to optimize microbiological characteristics. Acidification caused a decrease in bacterial diversity and microbial activity, which may be negative for the use in growing media, although the changes are limited. Sieving had limited effect on the microbiome of composts. Because of the limited effect on the microbiome, sieving of composts may be used flexible to improve (bio)chemical characteristics. This is the first study to assess the effects of maturation and optimization treatments to either increase organic matter content or lower pH in composts on the compost microbiome.
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Affiliation(s)
- Steffi Pot
- Division Forest, Nature and Landscape, Department of Earth and Environmental Sciences, KU Leuven, Geel, Belgium.,Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Plant Sciences Unit, Merelbeke, Belgium
| | - Caroline De Tender
- Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Plant Sciences Unit, Merelbeke, Belgium.,Department of Applied Mathematics, Computer Science and Statistics, Ghent University, Ghent, Belgium
| | - Sarah Ommeslag
- Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Plant Sciences Unit, Merelbeke, Belgium
| | - Ilse Delcour
- PCS Ornamental Plant Research, Destelbergen, Belgium
| | - Johan Ceusters
- Research Group for Sustainable Crop Production & Protection, Division of Crop Biotechnics, Department of Biosystems, KU Leuven, Geel, Belgium.,Centre for Environmental Sciences, Environmental Biology, UHasselt, Diepenbeek, Belgium
| | - Ellen Gorrens
- Lab4Food, Department of Microbial and Molecular Systems, KU Leuven, Geel, Belgium
| | - Jane Debode
- Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Plant Sciences Unit, Merelbeke, Belgium
| | - Bart Vandecasteele
- Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Plant Sciences Unit, Merelbeke, Belgium
| | - Karen Vancampenhout
- Division Forest, Nature and Landscape, Department of Earth and Environmental Sciences, KU Leuven, Geel, Belgium
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