Utilization of Sunflower Stalk Waste in Microbial Biomass Production with <i>Lactobacillus rhamnosus</i> GG

In this study, microbial biomass production was carried out using Lactobacillus rhamnosus GG (LGG), a probiotic bacterium, by utilizing sunflower stalks, an agricultural waste, as a carbon source. In the first stage, the optimal growth conditions for LGG were determined, and biomass production was conducted under these conditions. The growth parameters of LGG were optimized based on pH, temperature, carbon source, and incubation time. According to the findings, the highest growth and biomass production of LGG were achieved using glucose as a carbon source at 37°C, with pH 6 and an incubation period of 24 h. In the second stage, sunflower stalks were used as a carbon source in biomass production. After being sterilized, the sunflower stalks were ground. The sunflower stalk waste was added directly to the culture medium in its ground form and also processed using an ultrasound-assisted extraction method before being incorporated into the medium. The results indicated that the culture medium containing ultrasound-assisted extracted sunflower stalk waste served as a more effective carbon source, compared to glucose and lactose, which were used as carbon sources in optimization studies. By analyzing the growth rate of LGG on this substrate and its intracellular protein amount, sunflower stalks were demonstrated to be a suitable substrate for biomass production.