Enhancement of fruit byproducts through bioconversion by Hermetia illucens (Diptera: Stratiomyidae)

Bioconversion is a biological process by which organic materials are converted into products with higher biological and commercial value. During its larval stage the black soldier fly Hermetia illucens is extremely voracious and can feed on a wide variety of organic materials. To study the impact of different fruit byproducts on the insect's growth, final larval biomass, substrate reduction, bioconversion parameters, and larval nutritional composition, 10 000 black soldier fly larvae (BSFL) were reared on 7.0 kg of one of three substrates (strawberry, tangerine, or orange) or on a standard diet as a control. The results highlight that BSFL can successfully feed and grow on each of these diets, though their development time, growth rate, and final biomass were differently impacted by the substrates, with strawberry being the most suitable. The lipid and protein contents of BSFL were similar among larvae fed on different substrates; however, major differences were detected in ash, micronutrient, fiber, fatty acid, and amino acid contents. Overall, the results indicate that fruit waste management through the BSFL bioconversion process represents a commercially promising resource for regional and national agrifood companies. Our study offers new perspectives for sustainable and environmentally friendly industrial development by which fruit byproducts or waste might be disposed of or unconventionally enhanced to create secondary products of high biological and economic value, including BSFL biomass as animal feed or, in perspective, as alternative protein source for human nutrition.     

Hydroxylation of prostaglandin E1 by kidney cortex microsomal monooxygenase in the guinea pig

The incubation of [5,6-³H]prostaglandin E₁ ([³H]PGE₁) with guinea pig kidney cortex microsomes in the presence of NADPH in an atmosphere of air, resulted in chromatographically polar metabolites. The incubation products were treated with base which converted PGE₁ derivatives into PGB₁ derivatives, with a λ_max = 278 nm and the products were analyzed by TLC and high pressure-liquid chromatography (HPLC). Based on UV absorption, mobility on TLC and retention time in HPLC, as compared with authentic compounds, it was concluded that the two polar UV-absorbing peaks in HPLC represented 19-hydroxy-PGB₁ (19-OH-PGB₁) and 20-hydroxy-PGB₁ (20-OH-PGB₁). Further identification of the metabolites was obtained by derivatizing the incubation products as methyl esters and t-butyldimethylsilyl ethers, followed by co-injection with similarly derivatized authentic compounds in HPLC and gas chromatography. Finally, the derivatized metabolites were identified by comparing their mass fragmentation with that of similarly derivatized authentic compounds. There was an absolute requirement for NADPH, and NADH did not significantly support the hydroxylation of PGE₁. Inhibitors of microsomal monooxygenase (SKF 525A, metyrapone, and cytochrome c) inhibited the hydroxylation of PGE₁ by kidney cortex microsomes. By contrast, carbon monoxide at a CO:O₂ ratio of 5:1 did not inhibit the hydroxylation of PGE₁, pointing to a low or lack of CO sensitivity of the hydroxylation of PGE₁. The addition of PGE₁ or laurate to guinea pig kidney cortex microsomes elicited Type I spectral changes. The spectral dissociation constant (K_s) for PGE₁ was 2.4 × 10^?4m. The kinetic constants for 19- and 20-hydroxylations of PGE₁ were determined. The K_M values for the 19- and 20-hydroxylation pathways were found to be identical, being 3.3 × 10^?4m, suggesting that the same enzyme is involved in both hydroxylations; however, the V_max values for 19-hydroxylation and 20-hydroxylation of PGE₁ were 50 nmol/hr and 20.8 nmol/hr respectively. These results demonstrate that PGE₁ is a substrate for the kidney cortex microsomal monooxygenase. The similarities and differences of the kidney monooxygenase in the guinea pig with that in the rat are discussed.     

Effect of inducers and inhibitors of monooxygenase on the hydroxylation of prostaglandins in the guinea pig. Evidence for several monooxygenases catalyzing omega- and omega-1-hydroxylation.

The incubation of prostaglandins (PG's) with liver microsomes from guinea pigs treated with inducers of monooxygenase (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), benzo[alpha]pyrene (benzpyrene), or a mixture of chlorinated biphenyls (Aroclor 1254)) exhibited marked elevation of 19-hydroxylation of PGE1, PGE2, PGA1, and PGA2 without affecting significantly 20-hydroxylation. However, with respect to effects on hydroxylation of a variety of xenobiotics, benzpyrene and Aroclor treatments differed markedly; whereas Aroclor treatment elevated the demethylation of ethylmorphine, benzphetamine, and p-chloro-N-methylaniline (PCMA), benzpyrene treatment had no effect on demethylation of ethylmorphine and only a marginal effect on that of PCMA. Both inducers elevated benzpyrene hydroxylation. By contrast, treatment with phenobarbital did not affect the hepatic microsomal PG's hydroxylation, although the hydroxylation of benzpyrene and the demethylation of ethylmorphine, benzphetamine, and PCMA were enhanced. Also, the hydroxylation of PG's by kidney cortex microsomes was not affected by either benzpyrene or Aroclor treatment. Inhibitors of monooxygenase were used to help delineate the type of monooxygenases induced. At low levels of alpha-naphthoflavone (ANF), benzpyrene hydroxylation in control- and Aroclor-treated guinea pigs was only little affected; by contrast, the same concentration of ANF markedly inhibited benzpyrene hydroxylation in benzpyrene-treated guinea pigs. On the other hand, metyrapone was most inhibitory in control guinea pigs. Support for the conclusion that benzpyrene induces in the guinea pig a hepatic monooxygenase with different characteristics than that found in control animals was provided by the observation that ANF (10 MICROM) inhibited PGE1 hydroxylation more pronouncedly in liver microsomes from benzpyrene-treated than from Aroclor-treated guinea pigs or controls. In addition, in benzpyrene and Aroclor-treated guinea pigs, ANF inhibited the (omega-1)-hydroxylation more pronouncedly than that of omega-hydroxylation. By contrast, metyrapone appeared to inhibit omega-hydroxylation more effectively than (omega-1)-hydroxylation. These results indicate that in the guinea pig, hydroxylation of PG's at the omega (20-) and omega-1 (19-) positions is catalyzed by different monooxygenases and that the inducers tested affect several hepatic monooxygenases with different specificities toward xenobiotics; however, with respect to PG's only the enzyme(s) involved in the 19-hydroxylation is affected.     

Effects of humic substances and soya lecithin on the aerobic bioremediation of a soil historically contaminated by polycyclic aromatic hydrocarbons (PAHs)

The high hydrophobicity of polycyclic aromatic hydrocarbons (PAHs) strongly reduces their bioavailability in aged contaminated soils, thus limiting their bioremediation. The biodegradation of PAHs in soils can be enhanced by employing surface-active agents. However, chemical surfactants are often recalcitrant and exert toxic effects in the amended soils. The effects of two biogenic materials as pollutant-mobilizing agents on the aerobic bioremediation of an aged-contaminated soil were investigated here. A soil historically contaminated by about 13 g kg(-1) of a large variety of PAHs, was amended with soya lecithin (SL) or humic substances (HS) at 1.5% w/w and incubated in aerobic solid-phase and slurry-phase reactors for 150 days. A slow and only partial biodegradation of low-molecular weight PAHs, along with a moderate depletion of the initial soil ecotoxicity, was observed in the control reactors. The overall removal of PAHs in the presence of SL or HS was faster and more extensive and accompanied by a larger soil detoxification, especially under slurry-phase conditions. The SL and HS could be metabolized by soil aerobic microorganisms and enhanced the occurrence of both soil PAHs and indigenous aerobic PAH-degrading bacteria in the reactor water phase. These results indicate that SL and HS are biodegradable and efficiently enhance PAH bioavailability in soil. These natural surfactants significantly intensified the aerobic bioremediation of a historically PAH-contaminated soil under treatment conditions similar to those commonly employed in large-scale soil bioremediation.     

Determination of 1-aryl-4-propylpiperazine pKa values: The substituent on aryl modulates basicity

In order to design a potential drug, it is important to know its pK_a because the protonation state of the molecule will be critical for ligand–receptor interaction and for the pharmacokinetic of the molecule. pK_a values of a series of 1-(substitutedphenyl)-4-propylpiperazines were measured to study how the presence of a substituent on the phenyl ring modulates the basicity of N-4 nitrogen. pK_a values indicated that the position of the substituent was crucial. In general, the introduction of the substituent in ortho-position of the phenyl ring increased the basicity of the molecule. This effect appeared to be related to steric and conformational effects and not to the electronic properties of the substituent. On the other hand, meta- and para-substituted derivatives showed a slight decrease of pK_a that was qualitatively consistent with the electronic properties of the substituent.