Isolation and Optimization of Culture Conditions of a Bioflocculant-Producing Fungi from Kombucha Tea SCOBY

Abstract

Biolocculants are gaining attention in research due to their environmental friendliness and innocuousness to human in comparison to the conventional flocculants. The present study aimed to investigate the ability of fungi from Kombucha tea SCOBY to produce effective bioflocculant in bulk. A 16S rRNA gene sequence analysis was utilized to identify the isolate. The medium composition (carbon and nitrogen sources) and culture conditions (inoculum size, temperature, shaking speed, pH, and time) were optimized using one-factor-at-a-time method. The functional groups, morphology, and crystallinity of the bioflocculant were evaluated using Fourier transform infrared (FT-IR), scan electron microscope (SEM) and X-ray diffractometry (XRD). The fungus was found to be Pichia kudriavzevii MH545928.1. It produced a bioflocculant with flocculating activity of 99.1% under optimum conditions; 1% (v/v) inoculum size, glucose and peptone as nutrient sources, 35 °C, pH 7 and the shaking speed of 140 rpm for 60 h. A cumulus-like structure was revealed by SEM; FT-IR displayed the presence of hydroxyl, carboxyl, amine, and thiocynates. The XRD analysis demonstrated the bioflocculant to have big particles with diffraction peaks at 10° and 40° indicating its crystallinity. Based on the obtained results, P. kudriavzevii MH545928.1 has potential industrial applicability as a bioflocculant producer.

Production and Characterization of a Bioflocculant from Pichia kudriavzevii MH545928.1 and Its Application in Wastewater Treatment

“…This implies that carbohydrates are the most active components during the flocculation process. Moreover, the high carbohydrate content affirmed our previous study that the bioflocculant is thermally stable [ 24 ]. Bioflocculants dominated by protein content are known to be heat sensitive as proteins denature easily at high temperatures [ 47 ].…”

“…In our previous study, we isolated, identified and optimized culture conditions for a bioflocculant producing Pichia kudriavzevii MH545928.1 from Kombucha tea SCOBY [ 24 ]. Pichia kudriavzevii is the teleomorph of the Candida krusei that was previously regarded as Issatchenkia orientali .…”

Isolation and Optimisation of Culture Conditions for a Marine Bioflocculant-Producing Bacterium and Application of Its Bioflocculant in Wastewater Treatment

“…About 50 mL of the medium was poured into different test tubes and autoclaved at 121 °C for 15 min. A loopful of the isolates was inoculated into the activation broth and incubated in a rotary shaker at 160 rpm, 37 °C for 24 h [ 24 ].…”

Isolation of a Marine Bacterium and Application of Its Bioflocculant in Wastewater Treatment

“…The inoculum size greater than 1% led to the decrease in flocculating activity. The decrease might have been due to the extreme niche overlap of B. subtilis CSM5, which might have resulted in the inhibition of the bioflocculant production [28]. Generally, the inoculum sizes that fall within the range of 1 to 5% are of economic preferences [36].…”

“…Thereafter, 2 mL of the culture broth was drawn every 12 h up to 96 h. The samples were then centrifuged at 12,000 rpm for 16 min. The supernatant was then used to evaluate the flocculating activity as previously described (see Section 2.2) [28].…”