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Li J, Liu S, Yang C, Keyhani NO, Pu H, Lin L, Li X, Jia P, Wu D, Pan J, Stevenson PC, Fernández-Grandon GM, Zhang L, Chen Y, Guan X, Qiu J. Characterization of an α-Amylase from the Honeybee Chalk Brood Pathogen Ascosphaera apis. J Fungi (Basel) 2023; 9:1082. [PMID: 37998887 PMCID: PMC10672707 DOI: 10.3390/jof9111082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 11/01/2023] [Accepted: 11/02/2023] [Indexed: 11/25/2023] Open
Abstract
The insect pathogenic fungus, Ascosphaera apis, is the causative agent of honeybee chalk brood disease. Amylases are secreted by many plant pathogenic fungi to access host nutrients through the metabolism of starch, and the identification of new amylases can have important biotechnological applications. Production of amylase by A. apis in submerged culture was optimized using the response surface method (RSM). Media composition was modeled using Box-Behnken design (BBD) at three levels of three variables, and the model was experimentally validated to predict amylase activity (R2 = 0.9528). Amylase activity was highest (45.28 ± 1.16 U/mL, mean ± SE) in media composed of 46 g/L maltose and1.51 g/L CaCl2 at a pH of 6.6, where total activity was ~11-fold greater as compared to standard basal media. The enzyme was purified to homogeneity with a 2.5% yield and 14-fold purification. The purified enzyme had a molecular weight of 75 kDa and was thermostable and active in a broad pH range (> 80% activity at a pH range of 7-10), with optimal activity at 55 °C and pH = 7.5. Kinetic analyses revealed a Km of 6.22 mmol/L and a Vmax of 4.21 μmol/mL·min using soluble starch as the substrate. Activity was significantly stimulated by Fe2+ and completely inhibited by Cu2+, Mn2+, and Ba2+ (10 mM). Ethanol and chloroform (10% v/v) also caused significant levels of inhibition. The purified amylase essentially exhibited activity only on hydrolyzed soluble starch, producing mainly glucose and maltose, indicating that it is an endo-amylase (α-amylase). Amylase activity peaked at 99.38 U/mL fermented in a 3.7 L-bioreactor (2.15-fold greater than what was observed in flask cultures). These data provide a strategy for optimizing the production of enzymes from fungi and provide insight into the α-amylase of A. apis.
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Affiliation(s)
- Jincheng Li
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (J.L.); (S.L.); (C.Y.); (H.P.); (L.L.); (X.L.); (L.Z.); (Y.C.)
| | - Sen Liu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (J.L.); (S.L.); (C.Y.); (H.P.); (L.L.); (X.L.); (L.Z.); (Y.C.)
| | - Chenjie Yang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (J.L.); (S.L.); (C.Y.); (H.P.); (L.L.); (X.L.); (L.Z.); (Y.C.)
| | - Nemat O. Keyhani
- Department of Biological Sciences, University of Illinois, Chicago, IL 60607, USA;
| | - Huili Pu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (J.L.); (S.L.); (C.Y.); (H.P.); (L.L.); (X.L.); (L.Z.); (Y.C.)
| | - Longbin Lin
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (J.L.); (S.L.); (C.Y.); (H.P.); (L.L.); (X.L.); (L.Z.); (Y.C.)
| | - Xiaoxia Li
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (J.L.); (S.L.); (C.Y.); (H.P.); (L.L.); (X.L.); (L.Z.); (Y.C.)
| | - Peisong Jia
- Institute of Plant Protection, Xinjiang Academy of Agricultural Sciences, Urumqi 830091, China;
| | - Dongmei Wu
- Biotechnology Research Institute, Xinjiang Academy of Agricultural and Reclamation Sciences, Shihezi 832061, China;
| | - Jieming Pan
- College of Biology & Pharmacy, Yulin Normal University, Yulin 537000, China;
| | - Philip C. Stevenson
- Natural Resources Institute, University of Greenwich, Chatham Maritime ME4 4TB, UK; (P.C.S.); (G.M.F.-G.)
| | | | - Liaoyuan Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (J.L.); (S.L.); (C.Y.); (H.P.); (L.L.); (X.L.); (L.Z.); (Y.C.)
| | - Yuxi Chen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (J.L.); (S.L.); (C.Y.); (H.P.); (L.L.); (X.L.); (L.Z.); (Y.C.)
| | - Xiayu Guan
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Junzhi Qiu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (J.L.); (S.L.); (C.Y.); (H.P.); (L.L.); (X.L.); (L.Z.); (Y.C.)
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StcU-2 Gene Mutation via CRISPR/Cas9 Leads to Misregulation of Spore-Cyst Formation in Ascosphaera apis. Microorganisms 2022; 10:microorganisms10102088. [PMID: 36296364 PMCID: PMC9607276 DOI: 10.3390/microorganisms10102088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 10/15/2022] [Accepted: 10/17/2022] [Indexed: 11/05/2022] Open
Abstract
Ascosphaera apis is the causative agent of honey bee chalkbrood disease, and spores are the only known source of infections. Interference with sporulation is therefore a promising way to manage A. apis. The versicolorin reductase gene (StcU-2) is a ketoreductase protein related to sporulation and melanin biosynthesis. To study the StcU-2 gene in ascospore production of A. apis, CRISPR/Cas9 was used, and eight hygromycin B antibiotic-resistant transformants incorporating enhanced green fluorescent protein (EGFP) were made and analyzed. PCR amplification, gel electrophoresis, and sequence analysis were used for target gene editing analysis and verification. The CRISPR/Cas9 editing successfully knocked out the StcU-2 gene in A. apis. StcU-2 mutants had shown albino and non-functional spore-cyst development and lost effective sporulation. In conclusion, editing of StcU-2 gene has shown direct relation with sporulation and melanin biosynthesis of A. apis; this effective sporulation reduction would reduce the spread and pathogenicity of A. apis to managed honey bee. To the best of our knowledge, this is the first time CRISPR/Cas9-mediated gene editing has been efficiently performed in A. apis, a fungal honey bee brood pathogen, which offers a comprehensive set of procedural references that contributes to A. apis gene function studies and consequent control of chalkbrood disease.
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Maccaro JJ, Moreira Salgado JF, Klinger E, Argueta Guzmán MP, Ngor L, Stajich JE, McFrederick QS. Comparative genomics reveals that metabolism underlies evolution of entomopathogenicity in bee-loving Ascosphaera spp. fungi. J Invertebr Pathol 2022; 194:107804. [PMID: 35933037 PMCID: PMC10793876 DOI: 10.1016/j.jip.2022.107804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 07/16/2022] [Accepted: 07/26/2022] [Indexed: 10/16/2022]
Abstract
Ascosphaera (Eurotiomycetes: Onygenales) is a diverse genus of fungi that is exclusively found in association with bee nests and comprises both saprophytic and entomopathogenic species. To date, most genomic analyses have been focused on the honeybee pathogen A. apis, and we lack a genomic understanding of how pathogenesis evolved more broadly in the genus. To address this gap we sequenced the genomes of the leaf-cutting bee pathogen A. aggregata as well as three commensal species: A. pollenicola, A. atra and A. acerosa. De novo annotation and comparison of the assembled genomes was carried out, including the previously published genome of A. apis. To identify candidate virulence genes in the pathogenic species, we performed secondary metabolite-oriented analyses and clustering of biosynthetic gene clusters (BGCs). Additionally, we captured single copy orthologs to infer their phylogeny and created codon-aware alignments to determine orthologs under selective pressure in our pathogenic species. Our results show several shared BGCs between A. apis, A. aggregata and A. pollenicola, with antifungal resistance related genes present in the bee pathogens and commensals. Genes involved in metabolism and protein processing exhibit signatures of enrichment and positive selection under a fitted branch-site model. Additional known virulence genes in A. pollenicola, A. acerosa and A. atra are identified, supporting previous hypotheses that these commensals may be opportunistic pathogens. Finally, we discuss the importance of such genes in other fungal pathogens, suggesting a common route to evolution of pathogenicity in Ascosphaera.
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Affiliation(s)
- J J Maccaro
- Department of Entomology, University of California Riverside, Riverside, CA, USA
| | - J F Moreira Salgado
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, RJ, Brazil; Department of Microbiology and Plant Pathology, University of California Riverside, Riverside, CA, USA
| | - E Klinger
- Department of Entomology, The Ohio State University, Columbus, OH, USA; USDA-ARS Pollinating Insect Biology Management Systematics Research Unit, Logan, UT, USA
| | - M P Argueta Guzmán
- Department of Entomology, University of California Riverside, Riverside, CA, USA
| | - L Ngor
- Department of Entomology, University of California Riverside, Riverside, CA, USA
| | - J E Stajich
- Department of Microbiology and Plant Pathology, University of California Riverside, Riverside, CA, USA.
| | - Q S McFrederick
- Department of Entomology, University of California Riverside, Riverside, CA, USA.
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Molecular Detection and Differentiation of Arthropod, Fungal, Protozoan, Bacterial and Viral Pathogens of Honeybees. Vet Sci 2022; 9:vetsci9050221. [PMID: 35622749 PMCID: PMC9145064 DOI: 10.3390/vetsci9050221] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 04/26/2022] [Accepted: 04/27/2022] [Indexed: 02/01/2023] Open
Abstract
The honeybee Apis mellifera is highly appreciated worldwide because of its products, but also as it is a pollinator of crops and wild plants. The beehive is vulnerable to infections due to arthropods, fungi, protozoa, bacteria and/or viruses that manage to by-pass the individual and social immune mechanisms of bees. Due to the close proximity of bees in the beehive and their foraging habits, infections easily spread within and between beehives. Moreover, international trade of bees has caused the global spread of infections, several of which result in significant losses for apiculture. Only in a few cases can infections be diagnosed with the naked eye, by direct observation of the pathogen in the case of some arthropods, or by pathogen-associated distinctive traits. Development of molecular methods based on the amplification and analysis of one or more genes or genomic segments has brought significant progress to the study of bee pathogens, allowing for: (i) the precise and sensitive identification of the infectious agent; (ii) the analysis of co-infections; (iii) the description of novel species; (iv) associations between geno- and pheno-types and (v) population structure studies. Sequencing of bee pathogen genomes has allowed for the identification of new molecular targets and the development of specific genotypification strategies.
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