The alphaproteobacterium Z. mobilis is the best bacterial ethanol producer endowed with unique physiological features . Therefore, Z. mobilis based-biorefinery is a promising biofuel production system at an industrial scale . Despite of its efficient ethanol production capacity, there are remaining challenges in employing Z. mobilis as biocatalyst. For example, Z. mobilis consumes limited range of feedstock as substrate . It is also known to be sensitive to certain abiotic stress [2, 3]. Yet, recent advances in Z. mobilis metabolic engineering has been overcoming these drawbacks and advancing its potential use for attaining environmentally-friendly biorefinery [2, 3].
In addition to ethanol production, rewiring metabolic pathways to produce other useful compounds has been lately explored in Z. mobilis [3–7]. This is to utilize and exploit its intrinsic capacity of fast catabolism that comes with small biomass accumulation . Considering that its prolific potential is expanding, novel approach to engineer or generate desirable Z. mobilis strains should be assessed.
Recently, co-culture based adaptive evolution, mixing several species in same culture to stimulate inter-species interaction, has been shown as a novel approach for improving physiological feature of industrially beneficial microorganisms by inducing frequent mutations . For example, serial co-culture of Candida glabrata and Pichia kudriavzevii significantly influenced growth and fermentation profile of co-evolved strains . The evolved strains conferred altered chemical complexity in produced wine . Zhou et al. showed that long term bacterial-yeast competition induced chromosomal arrangements in the yeast, rendering stress-tolerance, altered metabolism and other physiological features in the yeast Lachancea kluyveri . In addition to promoting mutation, co-culture has been also shown to promote production of particular metabolites in Streptomyces species, which otherwise not expressed in pure monoculture [11, 12]. Thus, inter-species interaction stimulates expression of cryptic genes. [11–13]. Such a response might also bias mutational events if the cryptic genes were continuously expressed during serial co-culture.
In addition to gaining potentially desirable traits, another advantage of the serial co-culture based adaptation method is to shed light on understanding of basic ecological aspect of species interaction [14, 15]. Given that Z. mobilis ecology and its natural habitat is yet rather enigmatic , the approach should be worth being examined in this regard as well.
In the present work, we adopted serial co-culture of Z. mobilis mixed with baker yeast Saccharomyces cerevisiae for strain generation. The aim of study was to see if Z. mobilis changes or rewire its ethanologenic feature through competition and interaction with S. cerevisiae over serial co-cultivation.