Exploring an Integrated Manure-Seawater System for Sustainable Cyanobacterial Biomass Production

Sido Sido

doi:10.3390/app9183888

Abstract

Cyanobacterial biomass is important for biofuel and biofertilizer, however, biomass production requires expensive chemical growth nutrients. To address this issue, we explored the use of inexpensive growth nutrient media from an integrated manure-seawater system for cyanobacterial biomass production. Salt-tolerant cyanobacterial strain HSaC and salt-sensitive cyanobacterial strain LC were tested to evaluate the potential of integrated manure-seawater media for sustainable cyanobacterial biomass production. As a prerequisite for seawater experiments, strain HSaC was grown at different NaCl concentrations (0 mM, 60 mM, 120 mM, 180 mM, 240 mM and 300 mM) to identify the optimum salt concentration. The highest biomass yield and photosynthetic pigment contents were obtained at 120 mM NaCl concentration. The highest exo-polysaccharide (EPS) content was obtained at 180 mM NaCl concentration. The treatments for the manure-seawater media were cow manure, pig manure, chicken manure and BG11, each with distilled water, diluted seawater and non-diluted seawater. The highest biomass and photosynthetic pigment yield for cyanobacterial strains LC and HSaC were obtained from 0.5 dS/m and 10 dS/m diluted seawater integrated with cow manure, respectively, but pig and chicken manure performed poorly. Overall, the biomass production and photosynthetic pigment results from cow manure-seawater were relatively better than those from the reference media (BG11). Based on the current findings, it is concluded that the growth nutrients from integrated cow manure-seawater can wholly substitute for the BG11 without affecting cyanobacterial growth, thereby reducing the usage of expensive chemical growth media. Thus, the results of study help to enhance the biomass production of both salt-sensitive and salt-tolerant cyanobacteria for sustainable biofuel and biofertilizer production.

Highlights

Cyanobacteria are a diverse group of prokaryotic oxygen-generating photosynthetic micro-organisms that conduct photosynthesis in a very similar way as higher plants [1].Cyanobacteria are able to produce useful metabolic products, such as pigment for feed additives, fatty acids, proteins and other nutrients [2]
We developed a cost-effective cyanobacterial growth media from integrated manure-seawater nutrients for sustainable cyanobacterial biomass production
Before we tested seawater as a nutrient source, we evaluated the growth of the salt-tolerant cyanobacterial strain HSaC

Summary

Introduction

Cyanobacteria are able to produce useful metabolic products, such as pigment for feed additives, fatty acids, proteins and other nutrients [2]. Because of the continuous increase in the global human population and degradation of natural resources, meeting the demand for obtaining sustainable food and energy without creating environmental problems has become a topic of concern. Cyanobacteria have recently emerged as a potential candidate that might meet the above mentioned criteria due to its capacity to effectively harvest natural solar energy, utilize water, CO2 and nutrients, and convert them into biomass [3]. The biomass of cyanobacteria can be used for many purposes, such as food production, biofertilizer for crop production and soil fertility, biofuels (energy), cosmetics, and medical applications [3].

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