Semi-solid-state fermentation: A promising alternative for neomycin production by the actinomycete Streptomyces fradiae

Elaeocarpus serratus L. leaves (EL) containing phenolic compounds and flavonoids, including myricitrin with pharmacological properties, could be valorized as nutritional additive in foods. In this study, the semi-solid-state fermentation of EL and black soymilk (BS) by Lactobacillus plantarum BCRC 10357 was investigated. Without adding EL in MRS medium, the β-glucosidase activity of L. plantarum quickly reduced to 2.33 ± 0.15 U/mL in 36 h of fermentation; by using 3% EL, the stability period of β-glucosidase activity was prolonged as 12.94 ± 0.69 U/mL in 12 h to 13.71 ± 0.94 in 36 h, showing positive response of the bacteria encountering EL. Using L. plantarum to ferment BS with 3% EL, the β-glucosidase activity increased to 23.78 ± 1.34 U/mL in 24 h, and in the fermented product extract (FPE), the content of myricitrin (2297.06 μg/g-FPE) and isoflavone aglycones (daidzein and genistein, 474.47 μg/g-FPE) at 48 h of fermentation were 1.61-fold and 1.95-fold of that before fermentation (at 0 h), respectively. Total flavonoid content, myricitrin, and ferric reducing antioxidant power in FPE using BS and EL were higher than that using EL alone. This study developed the potential fermented product of black soymilk using EL as a nutritional supplement with probiotics.

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Performance of Fungal Growth Through Integrated Gompertz Model and Respiratory Quotient by Solid State Fermentation in Multi-Layer Squared Tray Solid State Bioreactor with Aeration Strategies

10.21203/rs.3.rs-609415/v1 ◽

2021 ◽

Author(s):

Musaalbakri Abdul Manan ◽

Colin Webb

Keyword(s):

Solid State ◽

Solid State Fermentation ◽

Respiratory Quotient ◽

Fungal Growth ◽

Gompertz Model ◽

Solid Substrate ◽

Aspergillus Awamori ◽

Promising Alternative ◽

Fungal Activity ◽

On Line

Abstract A newly designed, laboratory-scaled and multi-layer squared tray solid state bioreactor (SSB), was developed and successfully operated in solid state fermentation (SSF) conditions. The bioreactor was divided into eight layers of squared perforated trays. Wheat bran was used as a solid substrate for the growth of Aspergillus awamori and Aspergillus oryzae. The SSB was equipped with an oxygen (O2)/carbon dioxide (CO2) gas analyser and a thermocouple. Continuous on-line monitoring of fungal growth could be performed by indirect methods that measure O2 consumed, production of CO2 and metabolic heat. The advantage of using this method is that there are no tedious and time-consuming sampling processes. The evolution of CO2, which represents an accumulation term, was integrated with time and fitted to the Gompertz model in a log-like equation. The Gompertz model generated values that may be used to stimulate and verify the experimental data. Results strongly suggest that the evolved and accumulated CO2, excellently described fungal growth. Simulated results agreed with experimental results. The respiratory quotient (RQ), which is the ratio of CO2 evolution rate (CER) to O2 uptake rate (OUR), was determined by the gas balance method. CER and OUR confirmed that measurements correlated to fungal activity. Each RQ values can explain the differences of each SFF process carried out. Yet, heat evolved by fungal activity also described fungal growth. The current findings is an excellent pre-liminary experimental work, evidencing that multi-layer squared tray SSB with forced moistened aeration present a promising alternative of instrumented bioreactors for SSF processes.

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