Fed‐batch fermentation of olive mill wastewaters for lipase production

Abstract

In the Mediterranean basin countries, huge amounts of olive mill wastewaters (OMW) are produced by the olive oil industry. It constitutes a serious environmental problem, nevertheless its composition turns OMW into a potential growth medium to lipolytic microorganisms. The aim of this work was to study lipase production as well as OMW degradation in fed-batch cultures of Candida cylindracea CBS 7869, Candida rugosa CBS 2275 and Yarrowia lipolytica W29 (ATCC 20460). Besides the improvement of lipase production, the fed-batch approach enhanced the effluent degradation, since it led to good COD and lipids reduction, both higher than 50%. C. rugosa achieved the highest value of lipase productivity (130 U L −1 h −1 ), in parallel with highest lipids reduction (77%). This study demonstrates that OMW are becoming a competitive and valuable growth medium in fermentation processes with lipolytic microorganisms. The fed-batch strategy used proved to be an efficient approach to enhance lipase production from OMW and to reduce significantly the final organic load of the medium.

Valorization of agro-industrial wastes towards the production of rhamnolipids

“…In this work, the agro-industrial waste OMW (which composition is summarized in Table 1) was evaluated as an inducer of rhamnolipid production. Although the composition of OMW depends on several factors as previously explained, the results herein showed are in accordance with previous characterizations of OMW obtained from the same region (Amaral et al, 2012;Gonçalves et al, 2009Gonçalves et al, , 2012.…”

“…The concentration of total carbohydrates and protein in these residues were determined using the phenolsulfuric and Lowry methods, respectively (Dubois et al, 1956;Lowry et al, 1951). Furthermore, OMW was characterized in terms of pH, total solids, total phenols, total lipids and long-chain fatty acids composition, using methodologies described elsewhere (Amaral et al, 2012;Gonçalves et al, 2009Gonçalves et al, , 2012. Total solids were determined by oven drying (105°C) to constant weight.…”

“…The generation of this residue is seasonal, associated to the production of olive oil, which in Portugal usually takes place between December and February. However, in other Mediterranean countries its production can comprise a longer period (from October to March) (Dermeche et al, 2013;Gonçalves et al, 2012). OMW is a significant pollutant and its disposal constitutes an environmental problem, due to its low degradability and its toxicity against microorganisms, plants and aquatic ecosystems (Dermeche et al, 2013).…”

Development of pH adjustment-based operational strategy to increase total phenol removal rate in biodegradation of olive mill wastewater by Rhodotorula glutinis

“…It was also reported that at neutral or alkaline pH, polyphenols transformed into phenolates, losing part of their antimicrobial activity and becoming a suitable carbon source for micro-organisms [10]. On the other hand, fed-batch systems used in the biotreatment of OMW are limited [13,14]. To our knowledge, however, a system for OMW biodegradation depending on the pH adjustment has not been reported yet.…”

Potential biovalorization techniques for olive mill biorefinery wastewater

“…59 Other valorization strategies could utilize the residual oil in OMWW by turning it into a potential growth medium for lipolytic micro-organisms. 57,58 Gonçalves et al 62 verifi ed this strategy by studying the lipase production from Candida cylindracea, Candida rugosa and Yarrowia lipolytica. Besides the improvement of lipase production, COD and lipids were reduced by more than 50%.…”