Millions of tons of citrus peel waste are produced every year as a byproduct of the juice industry. Citrus peel is rich in pectin and xyloglucan, but while the pectin is extracted for use in the food industry, the xyloglucan is currently not valorized. To target hydrolytic degradation of citrus peel xyloglucan into oligosaccharides, we have used bioinformatics to identify three glycoside hydrolase 12 (GH12) endoxyloglucanases (EC 3.2.1.151) from the citrus fruit pathogens Penicillium italicum GL-Gan1 and Penicillium digitatum Pd1 and characterized them on xyloglucan obtained by alkaline extraction from citrus peel. The enzymes displayed pH-temperature optima of pH 4.6-5.3 and 35-37°C. PdGH12 from P. digitatum and PiGH12A from P. italicum share 84% sequence identity and displayed similar kinetics, although kcat was highest for PdGH12. In contrast, PiGH12B from P. italicum, which has the otherwise conserved Trp in subsite -4 replaced with a Tyr, displayed a 3 times higher KM and a 4 times lower kcat/KM than PiGH12A, but was the most thermostable enzyme of the three Penicillium-derived endoxyloglucanases. The benchmark enzyme AnGH12 from Aspergillus nidulans was more thermally stable and had a higher pH-temperature optimum than the enzymes from Penicillum spp. The difference in structure of the xyloglucan oligosaccharides extracted from citrus peel xyloglucan and tamarind xyloglucan by the new endoxyloglucanases was determined by LC-MS. The inclusion of citrus peel xyloglucan demonstrated that the endoxyloglucanases liberated fucosylated xyloglucan oligomers, implying that these enzymes have the potential to upgrade citrus peel residues to produce oligomers useful as intermediates or bioactive compounds.

Contaminated fungi on dried salted fish of three species including Talang queenfish (TQF, Scomberroides commersonianus), Hamilton\'s thryssa fish (HTF, Thryssa hamiltonii), and Cobia fish (CF, Rachycentron canadum) were isolated and identified. One hundred and sixty-nine isolates were obtained from TQF and HTF, respectively, while no fungi were detected in CF. The dominant genera were Aspergillus spp. (n = 79), Penicillium spp. (n = 60), and non-sporulating fungi (n = 30). The representative groups of Aspergillus spp. (n = 6) and Penicillium spp. (n = 3) based on different morphological characteristics were selected for species identification by molecular methods involving ITS1-5.8s-ITS2 region and Matrix-Assisted Laser Desorption/Ionization Time-of Flight Mass Spectrometer (MALDI-TOF MS) analysis. The nine isolates were identified to be Aspergillus versicolor (n = 2), Aspergillus montevidensis (n = 3), Penicillium citrinum (n = 3), and Aspergillus sp. (n = 1). The antifungal activity of chitooligosaccharide-gallic acid (COS-GAL) conjugate against A. versicolor F1/10M9, A. montevidensis F1/30M20, and P. citrinum F1/23M14 was examined. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values were in the range of 0.625-2.5 mg/mL and 1.25-10 mg/mL, respectively. COS-GAL conjugate at the concentration of 5 mg/mL completely inhibited the spore germination of A. versicolor F1/10M9 and P. citrinum F1/23M14 after 72 h of treatment. COS-GAL conjugate at 4 × MIC mainly affected the mycelium of A. versicolor F1/10M9 and P. citrinum F1/23M14 after treatment with COS-GAL conjugate for 3 days by coating mycelium surface and reducing the size of mycelium. Therefore, COS-GAL conjugate could be used as a food additive to inhibit or prevent the growth of fungi contaminated in dried salted fish or other relevant products. PRACTICAL APPLICATION: During processing, dried salted fish can be contaminated with fungi, which may cause food poisoning and food spoilage. The contaminated fungi are capable of producing mycotoxin that is harmful to consumers. Synthetic food preservatives have long been used to inhibit fungal growth, but the side effects to consumers are of concern. Chitooligosaccharide is a nontoxic chitosan derivative produced from shrimp shell and its conjugate namely chitooligosaccharide-gallic acid conjugate showed high efficacy in inhibiting the growth of fungi including Aspergillus spp. and Penicillium spp. Therefore, it can serve as a natural alternative preservative for the prevention of fungal growth in dried salted fish.

Agrochemical wastewater, which is produced by the extensive use of herbicides, has become a serious environmental pollutant. In this study, culturable mycota were isolated from soils contaminated with herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA), and their ability to tolerate and remove 2,4-D was assessed. The mycota were isolated on solid medium supplemented with 10 mmol L-1 of MCPA or 2,4-D. Tolerance and removal assays were performed in synthetic wastewater, and removal was quantified by HPLC-UV and MS/MS. Fusarium spp., Aspergillus spp., and Penicillium spp. were the most frequently isolated genera. Six Penicillium strains were able to tolerate up to 25 mmol L-1 of 2,4-D. Within this group, two P. crustosum strains (RCP4 and RCP13) degraded more than 50% of the 2,4-D in the medium during the first 7 days of incubation. Removal percentages reached 54% for RCP4 and 75% for RCP13 after 14 days. These two strains, therefore, could potentially be considered for the design of bioaugmentation strategies aimed at reducing contamination by 2,4-D in wastewater.

This study aimed to verify the in vitro antifungal activity of Tahiti lemon essential oil (LEO) and its fractions, obtained by supercritical CO2 fractionation, against Penicillium sumatrense and Aspergillus niger isolated from pan bread. For this, LEO was solubilized (20 MPa and 40 °C) and fractionated (10 MPa and 40 °C) in supercritical CO2, resulting in soluble (SF) and precipitated (PF) fractions. LEO, SF and PF volatile compounds were identified by gas chromatography coupled to mass spectrometry (GC-MS) and semiquantified by gas chromatography with a flame ionization detector (GC-FID). To evaluate the in vitro antifungal activity of the essential oils (LEO, SF and PF), the minimal inhibitory and fungicidal concentrations (MIC and MFC, respectively) were determined using the 96-well plate methodology. For this, pan breads ware prepared with no preservatives and stored for seven days at 25 °C, and their pH, water activity and moisture contents were determined. Then, two predominant species (Penicillium sumatrense and Aspergillus niger) were isolated from pan breads, characterized according to their morphological and molecular characteristics, and were used in the antifungal activity studies. LEO and its fractions presented monoterpenes, sesquiterpenes and their oxygenated derivatives in their composition. Specifically, limonene was the major component identified in the essential oils. SF showed greater antifungal potential than PF and LEO, showing that supercritical CO2 fractionation could improve the antifungal efficiency of LEO. The results suggest that LEO and its fractions may contribute to the inhibition of Aspergillus niger and Penicillium sumatrense growth in pan breads.

Blue mold is a postharvest rot of pomaceous fruits caused by Penicillium expansum and a number of other Penicillium species. The genome of the highly aggressive P. expansum strain R19 was re-sequenced and analyzed together with the genome of the less aggressive P. solitum strain RS1. Whole genome scale similarities and differences were examined. A phylogenetic analysis of P. expansum, P. solitum, and several closely related Penicillium species revealed that the two pathogens isolated from decayed apple with blue mold symptoms are not each other\'s closest relatives. Among a total of 10,560 and 10,672 protein coding sequences respectively, a comparative genomics analysis revealed 41 genes in P. expansum R19 and 43 genes in P. solitum RS1 that are unique to these two species. These genes may be associated with pome fruit-fungal interactions, subsequent decay processes, and mycotoxin accumulation. An intact patulin gene cluster consisting of 15 biosynthetic genes was identified in the patulin producing P. expansum strain R19, while only a remnant, seven-gene cluster was identified in the patulin-deficient P. solitum strain. However, P. solitum contained a large number of additional secondary metabolite gene clusters, indicating that this species has the potential capacity to produce an array of known as well as not-yet-identified products of possible toxicological or biotechnological interest.

Three Penicillium species have been isolated from insect specimens in Korea; Penicillium sp., P. steckii, and P. polonicum. Penicillium sp. (KNU12-3-2) was isolated from Lixus imperessiventris, while P. polonicum (KNU12-1-8) and Penicillium steckii (KNU12-2-9) were isolated from Muljarus japonicas and Meloe proscarabaeus, respectively. The identification was based on the morphological characteristics of the fungi and in internal transcribed spacer analysis. This is the first report on the isolation of these three species of Penicillium from insects in Korea.