Effect of Light Stimulation on a Thermo-Cellulolytic Bacterial Consortium Used for the Degradation of Cellulose of Green Coconut Shells

The green coconut business is responsible for the generation of large amounts of waste. Sustainable development requires the transformation of such waste into value-added biotechnological products. The aim of this study was to optimize, by photostimulation, the hydrolysis of the coconut biomass. The thermo-cellulolytic consortium was collected from a composting pile, subjected to nutritional stress and irradiated either by Laser (λ660 ηm) or LED (λ632 ± 2 ηm). Microbial quantification after irradiation showed a significant stimulatory biological response. Despite cultures irradiated by LED significantly differed from the Laser-irradiated ones (p < 0.0001) both were significantly different from the control (p < 0.0001). The microbial consortium irradiated either by Laser or LED light showed the increase of RNA production and consequently protein synthesis causing anticipation and increase of the RBBR catabolism. The generation of products by cellulose hydrolysis (TRS and glucose) was significantly higher in the photostimulated groups, being the most effective catabolism observed within the first 48-h in the LED group and, after 144-h, in the Laser group. Photostimulation, especially by LED, might be considered as a booster of the bioprocess at low cost.