Computational analysis of successional changes in the microbial population and community diversity of the immobilized ma

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ORIGINAL ARTICLE

Computational analysis of successional changes in the microbial population and community diversity of the immobilized marine nitrifying bacterial consortium in a nitrifying packed bed bioreactor Boobal Rangaswamy1,2   · Ramya Ramankutty Nair1 · Cini Achuthan1 · Bright Singh Isaac Sarojini1  Received: 21 June 2020 / Accepted: 24 October 2020 / Published online: 11 November 2020 © King Abdulaziz City for Science and Technology 2020

Abstract Nitrifying bioreactor (NBR) connected to the recirculating aquaculture system (RAS), has a greater emphasis on the biological treatment of wastewater. Nitrifying bacterial consortium (NBC) formed bio-film on the substratum activating the NBR, and it was observed with high nitrification potential in shrimp maturation systems. Scanning Electron Microscopy (SEM) revealed the integrity of the biofilm substantiated with biomineralization. The fate of the matured bio-film population on subsequent operation under RAS, and the aggregated population at different points of RAS, including the rearing water were determined using fingerprints of Denaturing Gradient Gel Electrophoresis (DGGE). Altogether, 38 OTUs of biofilm sample and 35 OTUs of water samples represented the bacterial communities; the shared and unique OTUs indicated the diversity of the population at different time intervals in the operation of the NBR. The mathematical (range-weighted richness) and statistical (diversity indices) interpretation unveiled the OTUs based high bacterial diversity in the biofilm supporting the compositional changes and determined the distance between the community cluster. Ordination analyses indicated the population shift and stability of the activated bio-film till the matured biofilm community got established in the RAS. The DGGE with mathematical and statistical analysis revealed microbial diversity (high Shannon index, species richness and evenness), abundance (relative intensity), consecutive change in the population composition (OTUs, Rr index), and the dynamics (Δt) in the system during the operation. Keywords  Nitrifying bioreactor (NBC) · Recirculating aquaculture system (RAS) · Nitrifying bacterial consortia (NBC) · And Denaturing Gradient Gel Electrophoresis (DGGE)

Introduction Aquaculture is one of the developing food production sectors with intensification, and concomitantly there has been an increase in the output of waste material resulting in environmental degradation, a concern among environmental scientists (Arvanitoyannis and Kassaveti 2008). This created more emphasis on novel technologies for waste management and sustainable production (Martinez-Porchas and * Bright Singh Isaac Sarojini [email protected] 1



National Centre for Aquatic Animal Health, Cochin University of Science and Technology, Lakeside Campus, Cochin, Kerala 682016, India



Department of Biotechnology, Nehru Arts and Science College, Thirumalayampalayam, Coimbatore, Tamil Nadu 641105, India

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Martinez-Cordova 2012). Under such innovations, RAS ranks first with minimal water loss, h