Biomass production of Vishniacozyma victoriae using agro-industrial wastes in batch and semicontinuous cultures

GORORDO, M. FLORENCIA.; SANGORRÍN, MARCELA PAULA; LUCCA, MARIA ESTER

Cordoba

Congreso; XVII Congreso Argentino de Microbiología General; 2022

Biological control agents (BCA) are widely proposed as an alternative to chemicalfungicides to prevent fungal diseases in organic pear production. Vishniacozyma victoriaeyeast was previously isolated and selected because of its biocontrol effectiveness. To obtainhigh amounts of BCA it is necessary to scale up the production process using differentreactor configurations and low-cost culture media. This work aimed to evaluate the biomassproduction of V. victoriae in batch (BC) and semicontinuous (SC) culture using two agroindustrial wastes. Cheese whey powder (CWP), from the lactic industry and apple juicewaste (AJW), from the juice industry.Two culture media were optimized using a central composite design (DCC), thecomposition for each was: AJW 44.4%(v/v), urea 2 g/L, KH2PO4 7.3 g/L, and CWP 80 g/L,(NH4)2SO4 1.2 g/L, KH2PO4 10 g/L. BC and SC fermentations were carried out in a 15 Lstirred-tank bioreactor with 12 L of working volume with each culture medium. The SC wasfed three times at 24-h intervals, before feeding, 5 L of culture contents was removed, and5 L of fresh culture was then added reaching 27 L volume production. All fermentations werecarried out at 20°C, 300 rpm and 0.64 vvm of aeration. The colony forming unit (CFU) anddry weight (DW) of the yeast biomass were evaluated in both cultures. The DNS methodwas used to determine the total reducing sugar (RS) concentration andthe ammonium content was analyzed using an enzymatic kit.In BC cultures with CWP, the dry weight was 103 g and the CFU was 3.3.1013reaching a 1.5 g/h production in 68 h of incubation whereas with AJW we obtained 124 gDW and 3.1013 CFU after 62 h of incubation with a 2 g/h of production. In SC culture, weobtained a total of 221.2 g DW and 1.8.1014 CFU after 105 h of incubation reaching aproduction of 2.1 g/h and 300.8 g DW and 3.9.1019 CFU after 127 h of incubation reachinga production of 2.4 g/h using CWP and AJW respectively. The initial ammonium content was0.44-0.55 g/L in CWP and the consumption was 0.33 g/L in BC and 0.48 g/L in SC, instead,using AJW the initial content was 0.87-1.1 g/L and the consumption was 0.41 g/L in BC and0.54 g/L in SC. The initial RS concentration was 45-47 g/L using AJW and the consumptionwas 19 and 21 g/L for BC and SC respectively, instead, using CWP the initial RSconcentration was 40-66 g/L and the consumption was 15 and 20 g/L for BC and SCrespectively.The results showed that SC culture improves BCA production and reduces the totaldowntime (harvest, clean, sterilize and prepare) between successive reactors for biomassproduction. Using AJW increases 5 times the UFC and 1.4 times the dry weight, instead,these parameters are similar in BC culture with both agro-industrial wastes. Future researchwill focus on evaluating and comparing the effectiveness of BCA biomass grown in bothculture medium and in the two reactor configuration in semi-commercial scale assays in apacking line.