Screening of anaerobic bacteria with the ability to decolorize molasses melanoidin.

Abstract

The screening of facultative anaerobes with melanoidin-decolorizing activity (MDA)was performed, and some strains were isolated from stored waste water of an alcohol fermentation involving molasses. One of them, strain W-NS,showed high and stable MDA,and was identical with Lactobacillus hilgardii. The decolorization yield of this strain under the optimal conditions was only 28%, however, it was improved to 40% by immobilization of cells within Ca-alginate gel. Unlike Basidiomycetes and Ascomycetes, this strain decolorized smaller molecular weight fractions of melanoidin, quickly. Also, the MDA of this strain toward various synthetic melanoidin was quite different from that of Basidiomycetes. Melanoidin, a dark brown pigment, is one of the biopolymers that is hardly decomposed by microorganisms and is wildly distributed in nature. It is also present in molasses and 2429 Coriolus versicolor Ps4a. Furthermore, we4'5) reported the decolorization of molasses waste water by a thermophilic Aspergillus strain

Vinasses: characterization and treatments

“…Several fungi have been investigated for their ability to remove colour and COD (Table 5) (Satyawali and Balakrishnan 2008). Ohmomo et al (1988) concluded that the decolourization of melanoidins is due to two decomposition mechanisms. In the first one, melanoidins with lower molecular weight are attacked and in the second one, those with a high molecular weight are attacked.…”

Impacts of thermal hydrolysis

“…There are various fungi, algae and facultative bacteria capable of melanoidin decolorizing activity (MDA). A variety of facultative anaerobes exhibiting MDA have been identified which can remove approximately a quarter of melanoid present (Ohmomo et al, 1988). This would explain the work of Dwyer's group (2008), and later Higgins" team (2017) who demonstrated a reduction in various parameters associated with refractory components following digestion.…”

“…It was found that color removal could be improved by fortuitous metabolism by the addition of 1% glucose as a supplementary carbon source (Kumar & Chandra, 2006). The microbial decolorization of melanoidins is twofold, with certain organisms targeting smaller molecular weight melanoidins (such as W-NS strain) and others specializing against larger molecular weight melanoidins, such as Basidiomycetes and Ascomycetes (Ohmomo et al, 1988). In all instances, supplementation with either nitrogen or carbon source is almost always necessary because the microbial species are not able to utilize the refractory material as the sole carbon source.…”