Tag Archives: amino acid inhibitors

xxx S. Raita, I. Berzina, Z, Kusnere, M. Kalnins, I. Kuzmika and K. Spalvins
Herbicide-based selection of mutants for improved single cell protein synthesis: application and procedures
Abstract |

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Herbicide-based selection of mutants for improved single cell protein synthesis: application and procedures

S. Raita, I. Berzina, Z, Kusnere*, M. Kalnins, I. Kuzmika and K. Spalvins

Riga Technical University, Institute of Energy Systems and Environment,
Azenes street 12/1, LV 1048 Riga, Latvia
*Correspondence: zane.kusnere@rtu.lv

Abstract:

Enhancement of industrially important microbial strains using random mutagenesis is widely used. Screening of potential mutants accelerates the selection of mutants with desired properties such as improved synthesis of lipids, carotenoids, enzymes, or increased tolerance to unfavourable conditions. However, random mutagenesis has not been used to improve protein biosynthesis in microorganisms, and a method for screening these mutants has not yet been developed. The present work reviews the new concept of using herbicides as tools for selecting mutant microorganisms with improved protein biosynthesis. Several pure herbicide substances are amino acid inhibitors whose specific action can be used as a selective pressure for screening protein-rich mutants. The article summarises information about thirteen amino acid inhibitors that inhibit microorganisms and provides data on applicable doses and specifics of use. The article contains mutagenesis protocols and mutant selection strategies, supplemented by theoretical considerations for practical application.

Key words:

amino acid inhibitors, herbicide, mutagenesis, mutant selection, protein production, single cell protein

370-400 I. Berzina, S. Raita, M. Kalnins, K. Spalvins and I. Kuzmika
In search of the best technological solutions for creating edible protein-rich mutants: a multi-criteria analysis approach
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In search of the best technological solutions for creating edible protein-rich mutants: a multi-criteria analysis approach

I. Berzina*, S. Raita, M. Kalnins, K. Spalvins and I. Kuzmika

Riga Technical University, Institute of Energy Systems and Environment, Azenes street 12/1, LV 1048, Riga, Latvia
*Correspondence: Indra.Berzina@rtu.lv

Abstract:

Single-cell protein (SCP) is a promising alternative for replacing plant and animal-derived dietary proteins. SCP contains essential nutrients and high levels of essential amino acids (AA). Given the versatility of microbial strains and waste substrates that can be used as feedstocks, many variations of production processes can be explored. Improving these microorganism strains by enhancing their properties and productivity is vital to increasing SCP competitiveness. One of the options to enhance microorganism strains would be by creating mutants with better AA profiles. By using mutagenesis and AA inhibitors it should be possible the create novel strains with improved AA-producing properties. The use of AA inhibitors to promote selective pressure on SCP-producing strains is a novel concept and is not a widely explored approach, therefore, the further development of this method should be explored. This paper used a multi-criteria decision analysis method to evaluate different technological factors vital for creating protein-rich mutants. These factors are microorganism strains, agro-industrial waste substrates used as process feedstocks, AA inhibitors, and mutagenesis methods. Microorganisms Candida utilis and Bacillus subtilis showed the highest potential for being used. Molasses was the ‘closest to the ideal’ substrate to be used as feedstock for SCP production. As the most promising mutagenesis method ethyl methane sulphonate was selected. Glufosinate ammonium and methionine sulfoximine for both bacteria and fungi were identified as the best inhibitors for SCP-rich mutant selection. Identified combinations of optimal solutions for microorganisms, substrates, inhibitors, and mutagenesis techniques should be further investigated and evaluated in laboratory settings. This could help to increase SCP’s competitiveness as a sustainable protein source.

Key words:

agro-industrial waste, amino acid inhibitors, amino acids, biomass, herbicides, low-cost substrate, MCDA, microbial protein, microorganisms, multi-criteria analysis, mutagenesis, proteins, residues, SCP, single-cell proteins, TOPSIS, waste biomass

1285–1307 K. Spalvins, S. Raita, K. Valters and D. Blumberga
Improving single cell protein yields and amino acid profile via mutagenesis: review of applicable amino acid inhibitors for mutant selection
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Improving single cell protein yields and amino acid profile via mutagenesis: review of applicable amino acid inhibitors for mutant selection

K. Spalvins*, S. Raita, K. Valters and D. Blumberga

Riga Technical University, Institute of Energy Systems and Environment, Azenes street 12/1, LV 1048 Riga, Latvia
*Correspondence: kriss.spalvins@rtu.lv

Abstract:

Single cell protein (SCP) is a good alternative for substituting plant and animal derived dietary proteins, since SCP production is more environmentally friendly, consumes less water, requires smaller land areas and its effect on climate change is much less pronounced than it is in the case of agriculturally derived proteins. Another advantage of SCP is that it is possible to use a wide variety of biodegradable agro-industrial by-products for the cultivation of SCP producing microorganisms. However, to make single cell protein technology more widely available and improve its economic viability in such markets as animal and fish feed industries, it is necessary to improve the protein yields and amino acid profiles in microorganism strains capable of using agro-industrial by-products. One way to improve the strains used in the process is to create and select SCP-rich mutants. In this review authors propose a novel approach to create SCP-rich mutants with improved total protein content and essential amino acid profiles. In this approach amino acid inhibitors are used to create selective pressure on created mutants. It is expected that mutants with the most pronounced growth would either have higher total protein content, increased essential amino acid concentrations or both, when cultivated on selective plates containing one or multiple amino acid inhibitors. This paper reviews the most suitable groups of amino acid inhibitors that could be used for selection of new strains of SCP-producing microorganisms.

Key words:

agricultural residues, amino acid inhibitors, essential amino acids, herbicides, low-cost substrate, microbial protein, mutagenesis