Metabolic Pathway Analysis of Nitrogen and Phosphorus Uptake by the Consortium between C. vulgaris and P. aeruginosa.

A Suggey Guerra-Renteria,Orfil González-Reynoso,César Gómez-Hermosillo,M Alberto García-Ramírez,Yolanda González-García,Abril Gómez-Guzmán

doi:10.3390/ijms20081978

A Suggey Guerra-Renteria, Orfil González-Reynoso + Show 4 more

Open Access

https://doi.org/10.3390/ijms20081978

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Abstract

Anthropogenic activities have increased the amount of urban wastewater discharged into natural aquatic reservoirs containing a high amount of nutrients such as phosphorus (Pi and PO), nitrogen (NH and NO) and organic contaminants. Most of the urban wastewater in Mexico do not receive any treatment to remove nutrients. Several studies have reported that an alternative to reduce those contaminants is using consortiums of microalgae and endogenous bacteria. In this research, a genome-scale biochemical reaction network is reconstructed for the co-culture between the microalga Chlorella vulgaris and the bacterium Pseudomonas aeruginosa. Metabolic Pathway Analysis (MPA), is applied to understand the metabolic capabilities of the co-culture and to elucidate the best conditions in removing nutrients. Theoretical yields for phosphorus removal under photoheterotrophic conditions are calculated, determining their values as 0.042 mmol of PO per g DW of C. vulgaris, 19.43 mmol of phosphorus (Pi) per g DW of C. vulgaris and 4.90 mmol of phosphorus (Pi) per g DW of P. aeruginosa. Similarly, according to the genome-scale biochemical reaction network the theoretical yields for nitrogen removal are 10.3 mmol of NH per g DW of P. aeruginosa and 7.19 mmol of NO per g DW of C. vulgaris. Thus, this research proves the metabolic capacity of these microorganisms in removing nutrients and their theoretical yields are calculated.

Highlights

Diverse human activities have increased the amount of urban wastewater effluents discharged in natural aquatic reservoirs, containing a high amount of nutrients such as NH4+, NO3− and PO34− as well as organic contaminants
For the bacterium the nutrient removals yields were 4.90 mmol of phosphorus per g DW of P. aeruginosa and 10.30 mmol of ammonia per g DW of P. aeruginosa were obtained. These results indicate a more efficient uptake of inorganic phosphorous from microalga than from bacterium in the consortium, because of the alga requirements during photosynthetic metabolism according to Figure 1, it is important to mention that all the Extreme Pathways (ExPas) (2844) no matter the scheme, presented phosphorus removal, bacterium only exhibited a phosphorus removal in 33.3% of the total ExPas
A genome-scale metabolic network was rebuilt for the co-culture of C. vulgaris and P. aeruginosa

Summary

Introduction

Diverse human activities have increased the amount of urban wastewater effluents discharged in natural aquatic reservoirs, containing a high amount of nutrients such as NH4+, NO3− and PO34− as well as organic contaminants. These compounds have been identified as the main cause of eutrophication in natural aquatic reservoirs. Microalgae alone or in co-culture with bacteria offer a promising approach to removing and to re-using nutrients such as nitrogen and phosphorus, since they are possible to be assimilated into the biomass [1]. In addition to the wastewater effluent treatments, microalgae can be used for biodiesel production and even considered as a food source, making the tertiary wastewater treatment a sustainable and affordable process [3,4,5,6]

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