How Does Pikeperch Sander lucioperca Respond to Dietary Insect Meal Hermetia illucens? Investigation on Gut Microbiota, Histomorphology, and Antioxidant Biomarkers

Effects of feeding dietary defatted black soldier fly (Hermetia illucens) larvae meal (HI) on intestine microbiota, and on histomorphology, oxidative enzyme activities in liver and intestine of pikeperch (Sander lucioperca) were investigated. Four isoproteic (45% crude protein) and isolipidic (18% ether extract) diets were formulated to include 0% (CO), 9% (HI9), 18% (HI18) and 36% (HI36) of HI as replacement for fishmeal at 0, 25, 50, and 100%, respectively, and were fed to triplicate groups of juvenile pikeperch (initial body weight, 68.7 ± 7.1 g) for 84 days. No adverse effects were detected on the intestine of pikeperch fed diet groups, in terms of histomorphology (P > 0.05), while fish fed free or low levels of HI (≤ 9% in diet) showed significant liver degeneration (P < 0.05). Dietary HI significantly affected the oxidative enzyme activities of catalase and glutathione peroxidase in the liver, and glutathione S-transferase in the intestine (P < 0.05), while activity of superoxide dismutase in both liver and intestine was HI-dose independent (P > 0.05). Feeding HI-containing diets positively modulated the richness and diversity of intestinal microbiota, especially for HI18 group (P < 0.05). Inclusion HI up to 18% (50% fishmeal replacement) in pikeperch diets increased abundance of Clostridium, Oceanobacillus, Bacteroides, and Faecalibacterium genera, whereas the predominant bacterium, Cetobacterium was found in control and HI36 groups. This study reveals the potential of HI as an immune and health booster for juvenile pikeperch.

Whole-cell screening of oxidative enzymes using genetically encoded sensors

Genetically encoded biosensors enable efficient high-throughput screening of oxidative enzyme libraries.

Degradation of the Organochlorinated Herbicide Diuron by Rainforest Basidiomycetes

The main organochlorinated compounds used on agricultural crops are often recalcitrant, affecting nontarget organisms and contaminating rivers or groundwater. Diuron (N-(3,4-dichlorophenyl)-N ′ ,N ′ -dimethylurea) is a chlorinated herbicide widely used in sugarcane plantations. Here, we evaluated the ability of 13 basidiomycete strains of growing in a contaminated culture medium and degrading the xenobiotic. Dissipation rates in culture medium with initial 25 mg/L of diuron ranged from 7.3 to 96.8%, being Pluteus cubensis SXS 320 the most efficient strain, leaving no detectable residues after diuron metabolism. Pycnoporus sanguineus MCA 16 removed 56% of diuron after 40 days of cultivation, producing three metabolites more polar than parental herbicide, two of them identified as being DCPU and DCPMU. Despite of the strong inductive effect of diuron upon laccase synthesis and secretion, the application of crude enzymatic extracts of P. sanguineus did not catalyzed the breakdown of the herbicide in vitro, indicating that diuron biodegradation was not related to this oxidative enzyme.