Optimizing a submerged Monascus cultivation for production of red pigment with bug damaged wheat using artificial neural networks

Assessment of artificial neural networks to predict red colorant production by Talaromyces amestolkiae

Consumer choice is typically influenced by color, leading to an increase in the use of artificial colorants by industry. However, several artificial colorants have been banned due to their harmful effects on human health and the environment, leading to increased interest in colorants from natural sources. Natural colorants can be found in plants, insects, and microorganisms. The importance of evaluating the technical and cost feasibility for the production of natural colorants are important factors for the replacement of artificial counterpart. Therefore, it is highly beneficial to predict the productivity of microbial colorants. The use of statistical methods that generate polynomial models through multiple regressions can provide information of interest about a bioprocess. However, modeling and control of biological processes require complex systems models, because they are nonlinear and non-deterministic systems. In this regard, artificial neural networks are suitable for estimating bioprocess variables with systems modeling. In this work, two different strategies were developed to predict the production of red colorants by Talaromyces amestolkiae, namely simulation by artificial neural networks (ANN) and response surface methodology (RSM). The results showed that the colorant concentration predicted by ANN is closer to the experimental data than that predicted by polynomial models fitted by multiple regression. Thus, this work suggests that the use of ANN can identify the initial conditions of the culture parameters that have the greatest influence on colorant production and can be a tool to be employed to improve the production of biotechnological products, such as microbial colorants.

Utilization of low-cost agricultural by-product rice husk for Monascus pigments production via submerged batch-fermentation

BACKGROUND

Monascus pigments (MPs) produced by the genus Monascus, have been utilized for more than 2000 years in the food industry. In the present study, by submerged batch-fermentation (SBF), we were able to obtain a mutant strain with a high tolerance of inhibitory compounds generated from rice husk hydrolysate, allowing the production of MPs.

RESULTS

The mutant strain, M. Purpureus M523 with high rice husk hydrolysate tolerance was obtained using the atmospheric and room temperature plasma (ARTP) screening system, producing 39.48 U mL^-1 extracellular total MPs (yellow and orange MPs), using non-detoxified rice husk diluted sulfuric acid hydrolysate (RHSAH) as the carbon source in SBF. Extracellular MPs (exMPs) production was enhanced to 72.1 and 80.7 U mL^-1 in supplemented SBF (SSBF) and immobilized fermentation (IF) using non-detoxified RHSAH, with productivities of 0.16 and 0.37 U mL^-1  h^-1 , respectively. In addition, our findings revealed that despite having a high RHSAH tolerance, the mutant strain was unable to degrade phenolic compounds. Furthermore, we discovered that inhibitory compounds, including furfural (Fur) and 5'-hydroxymethyl furfural (5'-HMF), not only inhibit MP biosynthesis, but also regulate the conversion of pigment components.

CONCLUSION

The low-cost agricultural by-product, rice husk, can serve as an efficient substitute for MP production with high productivity via IF by Monascus spp. © 2021 Society of Chemical Industry.

Cost-effective pigment production by Monascus purpureus using rice straw hydrolysate as substrate in submerged fermentation

Monascus pigments (MPs), the secondary metabolites produced by the fungal strains of Monascus spp., hold commercial importance in not only the food and meat industries, but also therapeutic, cosmetic, and textile industries. To reduce the cost of MPs production, the utilization of rice straw hydrolysate as a substrate in submerged fermentation was investigated. The atmospheric and room temperature plasma (ARTP) mutation system was employed to develop a mutant strain Monascus purpureus M630, with high total extracellular Monascus pigments (exMPs) production of 34.12 U/mL in submerged fermentation with glucose-based medium. The results revealed that M. purpureus M630 produces 8.61 U/mL and 20.86 U/mL of exMPs in rice straw hydrolysate alone or in combination with glucose fermentation medium, respectively. Furfural (Fur) and 5'-hydroxymethyl furfural (5'-HMF), produced during pretreatment and hydrolysis of rice straw; are generally inhibitory for microbial growth and fermentation. Our findings revealed that M. purpureus M630 develops the tolerance and adaptation mechanisms in response to 5'-HMF and Fur during growth and MPs biosynthesis in rice straw hydrolysate. In conclusion, we report that rice straw hydrolysate can serve as an efficient and low-cost substitute for the MP production through submerged fermentation by Monascus spp.

Biological detoxification of Monascus purpureus pigments by heat-treated Saccharomyces cerevisiae

BACKGROUND

Today, there is an increasing concern about the consumption of synthetic colorants in food because of their possible health hazards. Monascus purpureus has attracted a great deal of attention as it produces various coloured pigments with high chemical stability, but it also produces citrinin, a secondary toxic metabolite, along with the pigments. This study aims to investigate the amount of pigment and citrinin reduction by different treatments with Saccharomyces cerevisiae such as heat treatment and suspension concentration.

RESULTS

The results indicated that the ability of S. cerevisiae regarding citrinin adsorption increased with increase of temperature and yeast concentration. The maximum extent of citrinin adsorption was related to heat treatment at 121 °C and a yeast concentration of 10⁵ cells mL^-1 , for which citrinin reduced from 4.43 mg L^-1 in control to 0.1 mg L^-1 . Heat treatment of 10³ cells mL^-1 suspension of S. cerevisiae cells at 50 °C, with 0.56 mg L^-1 citrinin remaining in the medium, showed the lowest ability for citrinin binding. The optimum absorbance of all red, orange and yellow pigments was observed for the heat treatment at 50 °C and yeast concentrations of 10³ and 10⁴ cells mL^-1 which was greater than that for the control.

CONCLUSIONS

We can conclude from this study that heat treatment with S. cerevisiae can be a useful way to reduce citrinin to below the standard limits. © 2019 Society of Chemical Industry.