Evaluation of Fungal Growth on Olive-Mill Wastewaters Treated at High Temperature and by High-Pressure Homogenization

Abstract

Reuse of olive mill wastewaters (OMWWs) in agriculture represents a significant challenge for health and safety of our planet. Phytotoxic compounds in OMWW generally prohibit use of untreated OMWWs for agricultural irrigation or direct discharge into surface waters. However, pretreated OMWW can have positive effects on chemical and microbiological soil characteristics, to fight against fungal soil-borne pathogens. Low amounts of OMWW following thermal (TT-OMWW) and high-pressure homogenization (HPH-OMWW) pretreatments counteracted growth of some of 12 soil-borne and/or pathogenic fungi examined. With fungal growth measured as standardized change in time to half maximum colony diameter, Δτ, overall, HPH-OMWW showed increased bioactivity, as increased mean Δτ from 3.0 to 4.8 days. Principal component analysis highlighted two fungal groups: Colletotrichum gloeosporioides, Alternaria alternata, Sclerotium rolfsii, and Rosellinia necatrix, with growth strongly inhibited by the treated OMWWs; and Aspergillus ochraceus and Phaeoacremonium parasiticum, with stimulated growth by the treated OMWWs. As a non-thermal treatment, HPH-OMWW generally shows improved positive effects, which potentially arise from preservation of the phenols.

Illumina-Based Analysis Yields New Insights Into the Fungal Contamination Associated With the Processed Products of Crataegi Fructus

“…The results showed that high temperature exhibited more inhibitory effect on the growth and aflatoxin production of these fungi than low temperature ( 36 ). Similarly, Cibelli et al observed that the growth of A. alternata was remarkably inhibited under high-temperature conditions ( 37 ). Moreover, many studies have reported the impact of other processing methods on the fungal community.…”

The Effects of Olive Mill Wastewater on Soil Microbial Populations

“…Similarly, the application of OMW to fruit infected with gray mold as well as plum tree orchards led to a significant decrease in fungal formation (Saadi et al, 2007;Vagelas et al, 2009). Several types of molds, namely Alternaria, Colletotrichum, Sclerotium, and Rosellinia, species were strongly inhibited by the application of OMW (Cibelli et al, 2017). In contrast, the spreading of OMW to a field of olive trees led to an almost 5-fold increase in arbuscular mycorrhizal fungi, which caused the fungal-bacterial ratio to increase from 0.23 to 1.11 (Mechri et al, 2008).…”

A Comparative Study on Trichoderma harzianum and a Combination of Candida/Bacillus as Tools for the Bioremediation of Table Olive Processing Water

“…B. pumilus (formerly known as Bacillus sp. strain 13M) [ 7 ], C. boidinii (strain 682) [ 8 ] and T. harzianum , strain Var119 [ 9 , 10 ], were used throughout this study. The bacterium was maintained on Tryptone Soya Agar (Oxoid, Basingstoke, UK) at 4 °C and grown in Tryptone Soya broth at 30 °C for 48 h; the yeast was maintained on YPG agar (yeast extract, 10 g/L; peptone, 20 g/L; glucose, 20 g/L) and grown in YPG broth incubated at 25 °C for 72 h, while the fungus was maintained on PDA (potato, 200 g/L; dextrose, 20 g/L; agar 20 g/L) at 4 ± 3 °C, and grown on PDA at 23 ± 2 °C for 15 days in the dark.…”