TL;DR
Findings demonstrates that optimized pretreatment coupled with selected indigenous bacterial isolates enhanced conversion of WB into protein-enriched microbial biomass, providing a basis for further development of lignocellulosic biomass valorization for SCP production.
Increasing global energy demand, together with the ecological impacts of fossil fuels, has renewed interest in biofuels. Microalgae such as Chlorella vulgaris have attracted significant interest because of their high carbohydrate content and rapid growth, as well as because their cultivation does not require arable land to the same extent as traditional crops. This positions C. vulgaris as a promising feedstock for third-generation bioethanol. In this study, dried C. vulgaris biomass was pretreated with α-amylase, followed by enzymatic hydrolysis to release fermentable sugars. A Box–Behnken design within response surface methodology was employed to investigate the effects of pH, inoculum size, and retention time on sugar release and ethanol production. The overall model was highly significant (F = 186.28, P < 0.001). Retention time exerted the greatest influence on hydrolysis and yield (F = 1551.39, P < 0.001), followed by pH (F = 48.50, P < 0.001); inoculum size had no significant effect (F = 2.49, P = 0.130). Quadratic terms contributed significantly to the model (F = 23.44, P < 0.001), whereas two-variable interactions were not significant (F = 1.28, P = 0.309). Peak yields exceeding 73% were obtained at pH 5.0–6.0 with a retention time of 72 h, and the validation trials closely matched the model predictions. ANOVA indicated a significant lack of fit (F = 26.64, P < 0.001), suggesting that the quadratic model did not adequately represent the response surface and that the actual relationship among the variables may be more complex than can be captured by a second-order equation. Despite this limitation, the close agreement between predicted and observed yields indicates that the model retained practical value for forecasting bioethanol production under the investigated fermentation conditions.
This study integrates microbial biotechnology, bioprocess optimization, and circular bioeconomy principles to valorize oilseed agro-industrial coproducts as low-cost inducing substrates for lipase production. Palm kernel cake (PKC), canola cake, andiroba cake, and brewer’s spent grain were evaluated as carbon sources for extracellular lipase production by the wild-type strain Trichoderma sp. LEPM-711 under submerged fermentation. Qualitative screening in olive oil/rhodamine B medium confirmed the strain’s lipolytic potential. Among the substrates tested, PKC showed the strongest induction, reaching 4.68 U mL−1, and was therefore selected for nitrogen supplementation and statistical optimization. Peptone supplementation increased lipolytic activity to 8.41 U mL−1 after 72 h. A Plackett–Burman design identified CaCl2·2H2O, CoCl2·6H2O, and peptone as significant medium components, while response surface methodology established the optimal operational conditions as pH 6.0, 106 spores mL−1, and 2% (w/v) PKC. Under these conditions, the crude enzymatic extract reached 18.31 U mL−1 at pH 7.0 and 45 °C, corresponding to an approximately 3.9-fold increase over the initial PKC fermentation. These findings support the use of Trichoderma sp. LEPM-711 and oilseed coproducts as a sustainable platform for enzyme production and residue upgrading within applied natural sciences.
The bioconversion of agro-industrial waste represents a promising strategy for the valorisation of residual biomass. However, the chemical complexity of these matrices and the presence of potentially inhibitory compounds limit their direct use in several bioprocesses. In this study, a quantitative, time-resolved method was used to select bacteria for bioconverting agro-industrial by-products. The growth dynamics of bacterial strains were screened using olive and grape pomace at different compositions (up to 15%) and formulations. An integrated scoring approach (0–1) was used to compare strain behaviour across experimental conditions. The results revealed strain-dependent variability, with a matrix concentration of 10% defined as the growth-limiting concentration, with approximately 50% positive results. Among the tested strains, Bacillus subtilis BL showed a consistent and reproducible response across different by-products and formulations, maintaining stable spore viability over time, particularly in formulations supplemented with calcium carbonate (on average 109 UFC/mL after 144 h). Mixed agro-industrial matrices promoted a more homogeneous and stable microbial response than individual components (reaching 109 CFU/mL after approximately 100 h), supporting their direct use in a real operating environment. Overall, this work proposes a transferable quantitative approach to selecting microorganisms suitable for bioconversion of agro-industrial by-products, providing a methodological basis for developing more reliable and reproducible formulations.
Cereal brans are abundant agro-industrial residues rich in polysaccharides, phenolic acids, and proteins, making them promising substrates for biotechnological valorization. This study investigated the progressive modification of wheat and corn bran during solid-state fermentation by three white-rot fungi (Pleurotus ostreatus, Fomes fomentarius and Ganoderma lucidum) to elucidate how fungal degradation performance is influenced by substrate composition. Fourier Transform Infrared Spectroscopy (FTIR) and Two-Dimensional Nuclear Magnetic Resonance (2D-NMR) analysis revealed preferential hemicelluloses degradation in both brans, accompanied by substantial alterations in signals associated with phenolic compounds, particularly ferulates. Among the tested fungi, F. fomentarius achieved the greatest carbohydrate reduction in wheat bran (51 % w/w) and P. ostreatus in corn bran (15 % w/w). All species degraded phenolic acids in wheat bran, while corn bran exhibited an enrichment of ferulic acid (up to 38 % w/w), indicating greater structural recalcitrance. Enzymatic profiling showed that wheat bran promoted higher xylanase and cellulase activities, whereas laccase activity was primarily species-dependent. Overall, these findings provide a systematic understanding of fungal mediated degradation pathways in cereal brans and highlight the critical role of substrate composition in shaping white-rot fungi strategies in lignocellulosic bioprocesses.
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