Oxygen uptake rate as a tool for on-line estimation of cell biomass and bed temperature in a novel solid-state fermentation bioreactor

Abstract

Direct measurement of cell biomass is difficult in a solid-state fermentation (SSF) process involving filamentous fungi since the mycelium and the solid substrate are often inseparable. However, respiratory data are rich in information for real-time monitoring of microbial biomass production. In this regard, a correlation was obtained between oxygen uptake rate (OUR) and biomass concentration (X) of Rhizopus oryzae MTCC 1987, during phytase production, in an intermittently mixed novel SSF bioreactor. To obtain the correlation, various models describing sigmoidal growth were tested, namely the logistic, Gompertz, Stannard, and Schnute models. Regression analysis of experimental results, at different operating conditions of inlet air flow rate and relative humidity suggested that OUR and X were correlated well by the logistic model (R > 0.90). To corroborate the use of respiratory data for on-line measurement of metabolic activity, OUR was related to metabolic heat generation rate (R), and the logistic model was found to satisfactorily correlate R and X as well. The model parameter, Y, when substituted into a heat transfer design equation, along with the values of other parameters and operating variables, gave reliable estimates of bed temperature. The correlations developed in the present study, between respiratory activity and biomass concentration may be extended on to other SSF processes for further validation and real-time monitoring of cell biomass and bed temperature.

Correlation of oxygen consumption with growth and red pigment production of Monascus purpureus in solid state fermentation of rice

“…The regression analysis of the fungal biomass production and the content of oxygen consumption shown in Table 1C revealed that the amount of oxygen consumed, fermentation time, and their interaction all had significant impact on fungal growth. Contrary to the findings of Arora et al (2018) who found that the oxygen consumption rate was directly related to Rhizopus oryzae cell biomass production, the present work showed the impact of the growth phase and the amount of oxygen supply on the growth since they affected the content of oxygen consumption. This was supported by the work of Bastos et al (2016) in which increased biomass and protein production using polyurethane foam as an inert support to increase oxygen transfer, since oxygen uptake affected enzyme production, which was required for fungal growth (Zhou et al, 2018;Abdella et al, 2020).…”

Newly designed multi-stacked circular tray solid-state bioreactor: analysis of a distributed parameter gas balance during solid-state fermentation with influence of variable initial moisture content arrangements

“…Ikasari and Mitchell (1998), using the Rhizopus oligosporus SSF process with rice bran as the substrate, observed similar results and reported an increase in OUR and heat evolved around 24 h, as well as a significance decrease was reported at 72 h fermentation. This finding was supported by Arora et al (2018), where a correlation was obtained between OUR and biomass concentration of R. oligosporus MTCC 1987 during phytase production in an intermittently mixed novel SSF bioreactor.…”

The prodigiosin change on the surface of Serratia marcescens detected by flow cytometry

“…The current trend in modern bioprocess technology is to monitor the process itself, not only by measuring the usual variables (concentrations in the bioreactor, pH, temperature, and the concentrations of the components of the off-gas and its flow) [41][42][43][44][45], but also by following the metabolic states of the cells [46]. FCM is usually used to count bacteria of different types and states, and to characterize bacterial physiology under different environmental conditions [47].…”