title: Culture dependent and independent genomic identification of Alicyclobacillus species in contaminated commercial fruit juices.
abstract: Alicyclobacillus is a genus of thermo-acidophilic, endospore-forming, bacteria species which occasionally cause spoilage of heat-processed fruit juices by producing guaiacol taint. In this study, Alicyclobacillus contamination of commercial fruit juices in West Africa was investigated using culture-dependent and -independent approaches. Firstly, a total of 225 fruit juice products from Ghana (n = 39) and Nigeria (n = 186) were enriched with yeast-starch-glucose (YSG) broth (pH 3.7) following heat shock at 80 °C for 10 min. Alicyclobacillus was detected in 11.6% (26) of samples. Isolates were identified to the genus taxonomic level by genus-specific PCR which targeted the squalene-hopene-cyclase (shc) gene followed by analysis of the almost-complete 16S ribosomal RNA (rRNA) gene sequences that identified 16 Alicyclobacillus acidoterrestris, 7 Alicyclobacillus acidocaldarius and 3 Alicyclobacillus genomic species 1 (Alicyclobacillus sp. 1). Whole-genome fingerprinting using PCR-RAPD primers Ba-10, F-61 and F-64 grouped the 16 A. acidoterrestris isolates into two genetic clusters. Furthermore, high performance liquid chromatographic (HPLC) analyses revealed the activity of vanillic-acid decarboxylase (vdc) in all A. acidoterrestris isolates due to guaiacol production from vanillic-acid. Lastly, species-specific PCR-DGGE targeting the 16S rRNA gene clearly discriminated between the guaiacol-producing A. acidoterrestris and the non-spoilage A. acidocaldarius group. Information provided by this study is fundamental to the development of effective strategies for the improvement of quality and shelf-life of processed tropical fruit juices in W. Africa.
authors.affiliation: Department of Microbiology, University of Lagos, Akoka, Lagos, Nigeria; Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, Bloemfontein, South Africa; Department of Biosciences and Biotechnology, Babcock University, Ilishan- Remo, Nigeria.
authors.forename: Babasola Adewunmi
authors.initials: BA
authors.lastname: Osopale
authors.affiliation: Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, Bloemfontein, South Africa.
authors.forename: Cornelia Regina
authors.initials: CR
authors.lastname: Witthuhn
authors.affiliation: Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, Bloemfontein, South Africa.
authors.forename: Jacobus
authors.initials: J
authors.lastname: Albertyn
authors.affiliation: Department of Microbiology, University of Lagos, Akoka, Lagos, Nigeria. Electronic address: foguntoyinbo@unilag.edu.ng.
authors.forename: Folarin Anthony
authors.initials: FA
authors.lastname: Oguntoyinbo
mesh_terms: D056450:Alicyclobacillus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D015169:Colony Count, Microbial; D016172:DNA Fingerprinting / Q000379:methods; D004269:DNA, Bacterial; D005516:Food Microbiology; D000067030:Fruit and Vegetable Juices / Q000382:microbiology*; D023281:Genomics; D005838:Genotype; D005869:Ghana; D006139:Guaiacol / Q000378:metabolism; D006358:Hot Temperature; D009549:Nigeria; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D019105:Random Amplified Polymorphic DNA Technique; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D006139:Guaiacol
keywords: Alicyclobacillus; Genome fingerprinting; Tropical fruit juices