Characterization of the microbiota in long- and short-term natural indigo fermentation

Abstract

The duration for which the indigo-reducing state is maintained in indigo natural fermentation batch dependent. The microbiota was analyzed in two batches of sukumo fermentation fluids that lasted for different durations (Batch 1: less than 2 months; Batch 2: nearly 1 year) to understand the mechanisms underlying the sustainability and deterioration of this natural fermentation process. The transformation of the microbiota suggested that the deterioration of the fermentation fluid is associated with the relative abundance of Alcaligenaceae. Principal coordinates analysis (PCoA) showed that the microbial community maintained a very stable state in only the long-term Batch 2. Therefore, entry of the microbiota into a stable state under alkaline anaerobic condition is an important factor for maintenance of indigo fermentation for long duration. This is the first report on the total transformation of the microbiota for investigation of long-term maintenance mechanisms and to address the problem of deterioration in indigo fermentation.

The Mechanism Underlying of Long-Term Stable Indigo Reduction State in Indigo Fermentation Using Sukumo (Composted Polygonum tinctorium Leaves)

“…Another study showed that a substantial change occurs in the microbiota during the early stage of fermentation, which is characterized by the appearance of Bacillaceae and subsequently by Anaerobranca sp. (93.1% similarity to Anaerobranca gottschalkii and this species belongs to Proteinivoraceae; Tu et al, 2019b). A previous research has shown that an initial drop in ORP is not directly linked to indigo reduction (Aino et al, 2010).…”

“…It was reported that the selection of microorganisms for the initial treatment with hot wood ash extract is important for the selection of necessary microorganisms, which consume oxygen in the early fermentation period (Tu et al, 2019a). In addition, entering stable alkaline anaerobic conditions dominated by obligately anaerobic Anaerobranca is important for the maintenance of an indigo reduced state of fermentation for a long duration (Tu et al, 2019b). Thus, the microbiota in the original material, sukumo, suffered twice from successive environmental pressures (hot wood ash extract and the disappearance of oxygen) at the beginning of the fermentation.…”

“…The study indicated that all the predominant bacteria that appeared during fermentation were derived from sukumo. To understand the mechanisms underlying the sustainability of indigo fermentation fluid, the microbiota of two batches of fermentation fluids with different durations for the indigoreducing state were analyzed (Tu et al, 2019b). The study showed that early predominance of obligate anaerobes, followed by successive changes into a stable microbiota is important for establishment of a fermentation fluid with long-lasting indigoreducing state.…”

Indigo-Mediated Semi-Microbial Biofuel Cell Using an Indigo-Dye Fermenting Suspension

“…The anode showed stability for 48 h and has possibility to show stability for longer time. The microbiota in the indigo fermentation change slightly in the long term; however, their indigo-reducing activity is maintained for 6-8 months [29,30]. This implies that the MBFC using the indigo-dye fermenting suspension maintains its activity for longer periods.…”

“…Furthermore, such alkaline conditions are convenient for suppressing the growth of contaminated microorganisms. The indigo-dye fermenting suspension can maintain its indigo-reducing activity for long periods even if the microbiota change [29,30]. Consequently, it is unnecessary to maintain sterile conditions.…”