Bacterial cellulose (BC) is emerging as an attractive large-scale polymer due to its superior properties. The dominant static culture for BC fermentation by bacteria or microbial consortium results in low productivity. Agitated culture, as an industrially projected technique, has been widely investigated but exclusively for cellulose-producing bacterial strains. Addressing this concern and evaluating the potential of residues as feedstock, this study highlights the utilization of microbial consortium BA2 and seven agro-industrial wastes including cocoa husks, sugarcane bagasse and others. Remarkably, rice bran (RB) appears as a promising substrate, achieving 2.14 g/L (dry basis) and outperforming the traditional HS medium, evident from a 15-day fermentation. A complex interplay between oxygen availability, glucose consumption and BC yield was revealed; while orbital and magnetic stirring with forced air ventilation (AFV) showed low BC yields and early biomass saturation, 4.07 g/L (dry basis) was targeted by magnetic stirring at 100 rpm from the start using only headspace air. However, beyond controlled operating conditions, mechanical agitation and favorable cellulose adhesion to metal in the stirred tank bioreactor negatively affect BC yield. This pattern uncovers the need for a further approach to the design of bioreactors when the microbial consortium is considered.

Membrane technology is primarily used for the separation and purification of biotechnological products, which contain proteins and enzymes. Membrane fouling during crossflow filtration remains a significant challenge. This study aims to initially validate crossflow filtration models, particularly related to pore-blocking mechanisms, through a comparative analysis with dead-end filtration models. One crossflow microfiltration (MF) and six consecutive ultrafiltration (UF) stages were implemented to concentrate laccase extracts from Pleurotus ostreatus 202 fungi. The complete pore-blocking mechanism significantly impacts the MF, UF 1000, UF 100 and UF 10 stages, with the highest related filtration constant (Kb_F) estimated at 12.60 × 10⁻⁴ (m⁻¹). Although the intermediate pore-blocking mechanism appears across all filtration stages, UF 100 is the most affected, with an associated filtration constant (Ki_F) of 16.70 (m⁻¹). This trend is supported by the highest purification factor (6.95) and the presence of 65, 62 and 56 kDa laccases in the retentate. Standard pore blocking occurs at the end of filtration, only in the MF and UF 1000 stages, with filtration constants (Ks_F) of 29.83 (s^−0.5m^−0.5) and 31.17 (s^−0.5m^−0.5), respectively. The absence of cake formation and the volume of permeate recovered indicate that neither membrane was exposed to exhaustive fouling that could not be reversed by backwashing.

Fermentation of agave sap, also known as exudate, has become an ancestral practice throughout Ecuadorian Andean. In Cayambe, located in this region, grows Agave americana L., which is recollected, and its sap is fermented. The agave-based fermented beverage, locally named "tzawar mishki", exhibits variable features, mainly ethanol concentration. In this work, fermentation conditions of agave sap were studied to enhance ethanol yield. Two thermal treatments for raw exudate were evaluated, pasteurization at boiling point for 30 minutes and sterilization at 121°C for 15 minutes; fermentation temperature, 30°C and room (around 18°C); and two yeast strains. Thermal pretreatments have a positive impact on reducing sugars and sucrose concentration. In the first case, an increase of 76 % and 30 % has been reported, while sucrose concentration quadrupled and doubled in pasteurized and sterilized samples, respectively. The highest ethanol concentration (63,31 g/L) and the best yield (66,21 %) were accomplished through agave sap pasteurized and fermented for 96 hours at 30°C. Negligible differences have been evidenced in ethanol and other volatile compounds content between the two yeast strains evaluated. Keywords: agave sap, ethanol, fermentation, fermentable sugars, yeast