Bacterial ecology of abattoir wastewater treated by an anaerobic digestor Linda Jabari, Hana Gannoun, Eltaief Khelifi, Jean-Luc Cayol, Jean-Jacques Godon, Moktar Hamdi, Marie-Laure Fardeau To cite this version: Linda Jabari, Hana Gannoun, Eltaief Khelifi, Jean-Luc Cayol, Jean-Jacques Godon, et al.. Bacterial ecology of abattoir wastewater treated by an anaerobic digestor. Brazilian Journal of Microbiology, Sociedade Brasileira de Microbiologia, 2016, 47 (1), pp.73-84. 10.1016/j.bjm.2015.11.029. hal- 02633155 HAL Id: hal-02633155 https://hal.inrae.fr/hal-02633155 Submitted on 27 May 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. b r a z i l i a n j o u r n a l o f m i c r o b i o l o g y 4 7 (2 0 1 6) 73–84 h ttp://www.bjmicrobiol.com.br/ Environmental Microbiology Bacterial ecology of abattoir wastewater treated by an anaerobic digestor a,b a,c a b Linda Jabari , Hana Gannoun , Eltaief Khelifi , Jean-Luc Cayol , d a b,∗ Jean-Jacques Godon , Moktar Hamdi , Marie-Laure Fardeau a Université de Carthage, Laboratoire d’Ecologie et de Technologie Microbienne, Institut National des Sciences Appliquées et de Technologie (INSAT), 2 Boulevard de la terre, B.P. 676, 1080 Tunis, Tunisia b Aix-Marseille Université, Université du Sud Toulon-Var, CNRS/INSU, IRD, MOI, UM 110, 13288 Marseille cedex 9, France c Université Tunis El Manar, Institut Supérieur des Sciences Biologiques Appliquées de Tunis (ISSBAT) 9, avenue Zouhaïer Essafi, 1006 Tunis, Tunisia d INRA U050, Laboratoire de Biotechnologie de l’Environnement, Avenue des Étangs, F-11100 Narbonne, France a r a t i c l e i n f o b s t r a c t Article history: Wastewater from an anaerobic treatment plant at a slaughterhouse was analysed to deter- Received 19 September 2014 mine the bacterial biodiversity present. Molecular analysis of the anaerobic sludge obtained Accepted 6 July 2015 from the treatment plant showed significant diversity, as 27 different phyla were identified. Firmicutes, Proteobacteria, Bacteroidetes, Thermotogae, Euryarchaeota (methanogens), and msbl6 Associate Editor: Welington Luiz de (candidate division) were the dominant phyla of the anaerobic treatment plant and repre- Araújo sented 21.7%, 18.5%, 11.5%, 9.4%, 8.9%, and 8.8% of the total bacteria identified, respectively. The dominant bacteria isolated were Clostridium, Bacteroides, Desulfobulbus, Desulfomicrobium, Keywords: Desulfovibrio and Desulfotomaculum. Our results revealed the presence of new species, gen- era and families of microorganisms. The most interesting strains were characterised. Three Bacterial ecology Biodiversity new bacteria involved in anaerobic digestion of abattoir wastewater were published. © 2015 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. This is Bacterial culture SSCP an open access article under the CC BY-NC-ND license PCR (http://creativecommons.org/licenses/by-nc-nd/4.0/). high fat and protein content of slaughterhouse waste makes Introduction wastewater a good substrate for anaerobic digestion, due to 1 its expected high methane yield. Numerous microorganisms For hygienic reasons, abattoirs use copious amounts of are involved in the anaerobic degradation of slaughterhouse water in their processing operations (slaughtering and clean- waste, any step of which may be rate-limiting depending on ing), which creates significant wastewater. In addition, the the waste being treated as well as the process involved. increased use of automated machines to process carcasses, The microorganisms involved in anaerobic digestion have along with the incorporation of washing at every stage, has not been fully identified; however, at least four groups of 2 increased water consumption in slaughterhouse facilities. The microorganisms are involved in this process. The first group ∗ Corresponding author. E-mail: [email protected] (M.-L. Fardeau). http://dx.doi.org/10.1016/j.bjm.2015.11.029 1517-8382/© 2015 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 74 b r a z i l i a n j o u r n a l o f m i c r o b i o l o g y 4 7 (2 0 1 6) 73–84 are the hydrolytic bacteria that degrade complex compounds Material and methods (protein, carbohydrates, and fat) into simpler compounds, such as organic acids, alcohols, carbon dioxide (CO2) and Origin of the sludge hydrogen. The second group are the hydrogen producing ace- togenic bacteria that use organic acids and alcohols to produce Anaerobic sludge samples were collected from an upflow acetate and hydrogen. The third group contains homoaceto- 7 anaerobic filter that treats abattoir wastewater in Tunisia. genic bacteria that can only form acetate from hydrogen, CO2, ◦ The digestor operated under both mesophilic (37 C) and ther- organic acids, alcohols, and carbohydrates. The fourth group ◦ mophilic (55 C) conditions. Samples were taken at the end of comprises methanogens that form methane from acetate, ◦ thermophilic phase and stored at 4 C. The sludge was then CO2, and hydrogen. Hydrolytic, acetogenic, and methanogenic analysed to determine the bacterial diversity present, first via microorganisms play an equally important role in anaer- bacterial culture. obic digestion and methane production. Optimal methane production is only achieved via the interaction of multiple 3 microorganisms, and therefore, biodegradation of molecules DNA extraction, PCR and SSCP analysis of the digestor in wastewater depends on the activity of all microbial groups sludge involved. Common fermentative bacteria include Lactobacillus, Eubac- Four milliliters of the anaerobic sludge sample were cen- terium, Clostridium, Escherichia coli, Fusobacterium, Bacteroides, trifuged at 6000 rpm for 10 min. Pellets were re-suspended in ␮ Leuconostoc, and Klebsiella. Acetogenic bacteria include Aceto- 4 mL of 4 M guanidine thiocyanate–0.1 M Tris pH 7.5 and 600 L 2 bacterium, Clostridium, and Desulfovibrio. Methane producing of N-lauroyl sarcosine 10%. Tw o hundred and fifty microlitres organisms are classified under domain Archaea and phylum of treated samples were transferred in 2 mL tubes and stored 4 ◦ Euryarchaeota. at −20 C. In order to better understand the function of a bac- Extraction and purification of total genomic DNA was terial population, a detailed description of the microbial implemented according to the protocol developed by Godon 8 ecosystem is necessary. One method is via molecular biol- et al. 5 ogy techniques. Recent advances in the molecular analysis Highly variable V3 regions of bacterial 16S rRNA genes were of bacterial ecosystems allow a better understanding of the amplified by PCR using bacterial (w49–w34) primers (Table 1). specific microorganisms involved in wastewater treatment. Samples were treated according to the protocol previously 9 There are only a few studies focused on microbial populations, described by Delbès et al. diversity and evolution in reactors fed with complex organic For electrophoresis, PCR–SSCP products were diluted in 1 ␮ wastes. Therefore, little is known about the composition water before mixing with 18.75 L formamide (Genescan- ␮ of these reactors. The development of advanced molec- Applied Biosystems) and 0.25 L internal standards (ROX, ular biology techniques has contributed to the detection, Genescan-Applied Biosystems) according to the protocol of 9 quantification, and identification of the bacterial populations SSCP described by Delbès et al. involved in the treatment of abattoir wastewater. For example, SSCP analyses were performed on an automatic sequencer cloning and sequencing of 16S rRNA gene fragments provide abi310 (Applied Biosystems). RNA fragment detection was information about the phylogeny of the microorganisms. done on the fluorescent w34 primer. The results obtained Additionally, single stranded conformation polymorphism were analysed by GeneScan Analysis 2.0.2 Software (Applied 6 (SSCP) offers a simple, inexpensive and sensitive method for Biosystems) as specified by Gannoun et al. For bacterial iden- detecting whether or not DNA fragments are identical in tification, pyrosequencing of the DNA samples using a 454 sequence, and can greatly reduce the amount of sequencing protocol was performed (Research and Testing Laboratory, 6 necessary. Lubbock, USA). This work aimed to study the bacterial ecology of an Methods of analysis for pyrosequencing data used herein 10–14 anaerobic digestor through both bacterial culture and molec- have been described previously. Sequences are first ular biological techniques. The bacteria involved in the depleted of barcodes and primers. Then, short sequences anaerobic digestion of abattoir wastewater were identified under 200 bp are removed, sequences with ambiguous base using classic microbiology techniques and molecular tools calls are removed, and sequences with homopolymer runs (sequencing of 16S rRNA and SSCP). Additionally, our results exceeding 6 bp are removed. Sequences are then denoised 6 were compared with those of Gannoun et al. to