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Pistachio green hull (PGH) represents the non-edible fraction obtained after the seed is harvested and is an important source of phenolic compounds. Solid-state fermentation (SSF) is a viable biotechnological and economical technique for extracting phenolic compounds. This study aimed to evaluate the SSF with Aspergillus niger GH1 to recover total phenolic compounds (TPC) with antioxidant capacity (AC) from PGH. For this, the time of higher TPC and AC (DPPH [2,2-diphenyl-1-picrylhydrazyl], ABTS [2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate)], FRAP [ferric reducing antioxidant power]) was selected. Then, moisture, inoculum concentration, and aeration rate were evaluated. A. niger GH1 was able to grow and colonize the PGH, with the higher value of TPC (23.83 mg/g of dry mass (gdm)) obtained after 24 h of culture, which significantly correlated with AC (Pearson's R = 0.69). Moisture and aeration rate were the main factors influencing TPC. The highest values for both TPC and AC were achieved in treatment 8 (60% moisture, 5 × 10 6 spores/mL, and 1 L/Kgwm min), resulting in a 129% and 1039% increase, respectively. Gallic acid 4- O -glucoside and geranine were identified in the PGH extracts using high-performance liquid chromatography coupled with mass spectrometry. The SSF provides eco-friendly alternatives for releasing bioactive compounds from PGH, adding value to this waste.

Sorghum contains antioxidants such as tannins. However, these are considered antinutritional factors since they are responsible for the low digestibility of proteins and carbohydrates. Nevertheless, these can be extracted by solid-state fermentation (SSF). Therefore, this study aimed to evaluate the effects of SSF from Aspergillus oryzae and Aspergillus niger Aa210 on the tannin contents, phenolic profiles determined by HPLC-MS, and antioxidant activities (ABTS, DPPH, and FRAP) of two genotypes of sorghum. The results showed that with SSF by A. niger Aa210, a higher tannin content was obtained, with yields of 70-84% in hydrolyzable tannins (HT) and 33-49% in condensed tannins (CT), while with SSF by A. oryzae the content of HT decreased by 2-3% and that of CT decreased by 6-23%. The extracts fermented by A. niger at 72 and 84 h exhibited a higher antioxidant activity. In the extracts, 21 polyphenols were identified, such as procyanidins, (+)-catechin, (-)-epicatechin, scutellarein, arbutin, and eriodictyol, among others. Therefore, SSF by A. niger was an efficient process for the release of phenolic compounds that can be used as antioxidants in different food products. It is also possible to improve the bioavailability of nutrients in sorghum through SSF. However, more studies are required.

Previously, we described the generation and initial characterization of four Tn5 mutants of Pseudomonas stutzeri strain KC with impaired ability to degrade carbon tetrachloride (Sepúlveda-Torres et al., 1999). In this study, we show cloning and sequencing of an 8.3 kbp region in which all four transposons were located. This fragment encodes eight potential genes and is located in the central part of the 25 kbp fragment recently identified by Lewis et al. (2000) and shown by them to be sufficient to confer carbon tetrachloride transformation capability upon other pseudomonads. The four transposon insertion mutants mapped in ORF's F and I designated by Lewis et al. (2000). This is consistent with the results by Lewis et al. (2000) that orfFis required for carbon tetrachloride degradation. We further established that orfl is required for CCl4 degradation since the three mutants in this ORF were unable to degrade carbon tetrachloride. We present our analysis of the gene and protein sequences from the 8.3 kbp region and propose a tentative model for the role of different genes in the synthesis and activity of pyridine-2,6-bis(thiocarboxylate) (PDTC), the secreted factor responsible for carbon tetrachloride dechlorination. We also found a putative promoter that overlaps with a Fur-box-like sequence in the region upstream of mutated genes. To test this putative promoter region and Fur-box, we generated and ligated DNA fragments containing wild-type and mutant Fur-boxes to a lacZ reporter. The wild-type fragment showed promoter activity that is regulated by the concentration of iron in the medium. Finally, we screened a selection of Pseudomonas strains, including P. putida DSMZ 3601--a strain known to produce PDTC--for the presence of the genes characterized in this study. None of the strains tested positive, suggesting that Pseudomonas stutzeri strain KC may possess a distinct biosynthetic pathway for PDTC production.