Bioprocess Optimization for Exopolysaccharides Production by Ganoderma lucidum in Semi-industrial Scale

Background: For many years, Ganoderma was highly considered as biofactory for the production of different types of bioactive metabolites. Of these bioactive compounds, polysaccharides gained much attention based on their high biotherapeutic properties. Therefore, special attention has been paid during the last years for the production of mushrooms bioactive compounds in a closed cultivation system to shorten the cultivation time and increase the product yield. Objective: This work focuses on the development of a simple cultivation strategy for exopolysaccharides (EPS) production using Ganoderma lucidum and submerged cultivation system. Results and Discussion: Therefore, this work is focused on the development of simple cultivation system for exopolysaccharides (EPS) production using Ganoderman lucidum. At first, the best medium supporting EPS production was chosen experimentally from the current published data. Second, like many EPS production process, carbon and nitrogen concentrations were optimized to support the highest production of polysaccharides in shake flask level. Furthermore, the process was scaled up in 16-L stirred tank bioreactor. The results clearly demonstrated that the best cultivation strategy was cultivation under controlled pH condition (pH 5.5). Under this condition the maximal volumetric and specific yield of EPS production were, 5.0 g/L and 0.42 g/g, respectively. Methods: For many years, Ganoderma was highly considered as biofactory for the production of different types of bioactive metabolites. Of these bioactive compounds, polysaccharides gained much attention based on their high biotherapeutic properties. Therefore, special attention has been paid during the last years for the production of mushrooms bioactive compounds in a closed cultivation system to shorten the cultivation time and increase the product yield. Conclusion: The current results clearly demonstrates the high potential use of submerged cultivation system as alternative to conventional solid state fermentation for EPS production by G. lucidum. Furthermore, optimization of both carbon and nitrogen sources concentration and scaling up of the process showed significant increase in both volumetric and specific EPS production.

Short-term Low Oxygen Treatment Immediately After Planting Alters Asparagus officinalis var. UC157’s Harvest Timing

To control asparagus harvest timing, we investigated the effects of short-term low (5%) oxygen (O2) treatment in the cultivation area on asparagus growth and yield using a closed cultivation system. During 120 days of cultivation, low O2 treatments were initiated at 0 to 4, 20 to 24, and 40 to 44 days after planting (DAP). The sprouting spears and control crown yield gradually decreased with increasing DAP. However, low O2 treatment at 0 to 4 DAP significantly delayed the decrease until 80 DAP, although the total yield did not change during cultivation. In contrast, low O2 treatments at 20 to 24 and 40 to 44 DAP did not affect yield performance. Taken together, short-term low O2 treatment immediately after planting can change the harvest timing of white asparagus and can be used for effective asparagus culturing in a closed system, such as a plant factory.

Comparison of Two Harvesting Methods for the Continuous Production of Indigo Plant (Polygonum Tinctorium) Leaves in a Closed-Cultivation System

Although the blue dye indigo has been chemically synthesized for over a century, there is an increasing interest in the indigo plant (Polygonum tinctorium) as a source of natural dyes and medicines. To maintain a stable supply of P. tinctorium throughout the year, we examined the effect of two harvesting methods on the leaf yield of this plant under a closed-cultivation system. With method 8c-M, all shoot branches >8 cm of the stem bottom were harvested and under method 2b-M, all branches, but two, were harvested at the stem bottom. Both methods enabled sustainable leaf yields from the same plants over 1 year. The total weight of shoot branches harvested by 8c-M was 1.86–3.11 times higher that of shoot branches harvested by 2b-M. Harvesting by 8c-M resulted in shoot branch weights lower than those from plants harvested with the 2b-M. Leaf/shoot ratio was increased in plants harvested by 8c-M. The content of indican, the precursor of indigo, in leaves was not significantly different between the two harvesting methods. Our data may provide a new continuous cultivation method of leaf crops all over years in controlled-cultivation systems.