Understanding the Mechanisms of Positive Microbial Interactions That Benefit Lactic Acid Bacteria Co-cultures.

Fanny Canon,Anne Thierry,Eric Guédon,Valérie Gagnaire,Thibault Nidelet

doi:10.3389/fmicb.2020.02088

Abstract

Microorganisms grow in concert, both in natural communities and in artificial or synthetic co-cultures. Positive interactions between associated microbes are paramount to achieve improved substrate conversion and process performance in biotransformation and fermented food production. The mechanisms underlying such positive interactions have been the focus of numerous studies in recent decades and are now starting to be well characterized. Lactic acid bacteria (LAB) contribute to the final organoleptic, nutritional, and health properties of fermented food products. However, interactions in LAB co-cultures have been little studied, apart from the well-characterized LAB co-culture used for yogurt manufacture. LAB are, however, multifunctional microorganisms that display considerable potential to create positive interactions between them. This review describes why LAB co-cultures are of such interest, particularly in foods, and how their extensive nutritional requirements can be used to favor positive interactions. In that respect, our review highlights the benefits of co-cultures in different areas of application, details the mechanisms underlying positive interactions and aims to show how mechanisms based on nutritional interactions can be exploited to create efficient LAB co-cultures.

Highlights

It is widely acknowledged that microorganisms have colonized most natural ecosystems and that no single strain grows in isolation, so that microbes are intertwined and constantly interacting
Before detailing how microorganisms interact together, it is crucial to define the numerous terms used in the literature which refer to their association, such as microbial community or consortium, and mixed or co-cultures
One example is the production of vitamin C, where Ketogulonicigenium vulgare converts L-sorbose into 2-keto-Lgulonic acid (2-KLG), the precursor of vitamin C, while Bacillus megaterium supplies growth factors to enable the growth of K. vulgare and the production of 2-KLG (Zou et al, 2013)

Summary

INTRODUCTION

It is widely acknowledged that microorganisms have colonized most natural ecosystems and that no single strain grows in isolation, so that microbes are intertwined and constantly interacting. Before detailing how microorganisms interact together, it is crucial to define the numerous terms used in the literature which refer to their association, such as microbial community or consortium, and mixed or co-cultures. Biotechnological processes are reliant on three types of assemblies: enriched natural communities, artificial cocultures and synthetic co-cultures (Figure 1). The first gathers natural communities, enriched or not, which are spontaneous associations of microorganisms within a specific biotope They present the highest complexity in terms of the microbial species present and of the resulting interactions. Enriched natural communities are oriented toward targeted results, meaning that only a few of the transformations possible are favored This is the case in traditional fermented foods such as cheese or kimchi, as well as in composting

Design of LAB Positive Interactions

Positive Interactions That Occur in the Microbial World

Mechanisms Underlying Positive Interactions

Findings

AUTHOR CONTRIBUTIONS