New insights into Pseudomonas fluorescens alginate biosynthesis relevant for the establishment of an efficient production process for microbial alginates

•A method for visualisation of alginate biosynthetic complexes is established.•The number of complexes does not limit alginate synthesis in P. fluorescens mucA.•The availability of fructose 6-phosphate is important for alginate yield.•Stress caused by metabolites may reduce both growth and alginate production level.