Optimization of Acid Protease Production by Aspergillus niger I1 on Shrimp Peptone Using Statistical Experimental Design

Medium composition and culture conditions for the acid protease production by Aspergillus niger I1 were optimized by response surface methodology (RSM). A significant influence of temperature, KH2PO4, and initial pH on the protease production was evaluated by Plackett-Burman design (PBD). These factors were further optimized using Box-Behnken design and RSM. Under the proposed optimized conditions, the experimental protease production (183.13 U mL−1) closely matched the yield predicted by the statistical model (172.57 U mL−1) with R2 = 0.914. Compared with the initial M1 medium on which protease production was 43.13 U mL−1, a successful and significant improvement by 4.25 folds was achieved in the optimized medium containing (g/L): hulled grain of wheat (HGW) 5.0; KH2PO4 1.0; NaCl 0.3; MgSO4(7H2O) 0.5; CaCl2 (7H2O) 0.4; ZnSO4 0.1; Na2HPO4 1.6; shrimp peptone (SP) 1.0. The pH was adjusted at 5 and the temperature at 30°C. More interestingly, the optimization was accomplished using two cheap and local fermentation substrates, HGW and SP, which may result in a significant reduction in the cost of medium constituents

Evaluation of Hypoglycemic and Hypolipidemic Activities

Abstract Functional properties and antioxidant activities in vitro and hypoglycaemic and hypolipidemic activities in vivo of protein hydrolysates prepared from muscle of grey triggerfish (Balistes capriscus) were investigated. Baliste protein hydrolysates (BPHs) were obtained by treatment with crude enzyme preparations from Bacillus mojavensis A21 (BPH-A21), crude enzyme extract from sardinelle (Sardinella aurita) viscera (BPH-S) and crude enzyme extract from Zebra blenny (Slaria basilisca) viscera (BPH-Z). The protein hydrolysate BPH-A21, BPH-S and BPH-Z contained high protein content 87.61%, 74.53% and 54.18%, respectively. The protein hydrolysates had an excellent solubility and possessed interfacial properties, which were governed by their concentrations. Analysis of amino acid composition revealed that Baliste capriscus protein hydrolysates (BPHs) were valuable sources of essential amino acids and rich in lysine and Arginine, which is one of the active ingredients for blood glucose control by inducing insulin release in both rats and humans. Treatment of alloxan-induced diabetic rats (AIDR) with BPHs revealed a significant inhibition of α -amylase activity in serum, as well as a reduction of blood glucose and glycated hemoglobin (HbA1c) levels in diabetic rats. Further, BPHs also decreased significantly the triglyceride (TG), totalcholesterol (TC) and LDL-cholesterol (LDL-c) levels in the serum and liver of diabetic rats, while they increased the HDL-cholesterol (HDL-c) level, which helped to maintain the homeostasis of blood lipids. Furthermore, BPHs exhibited potent protective effects against heart attack markers by reversing myocardial enzyme serum back to normal levels. BCPHs may also a marked decrease in the level of serum bilirubin as well as in the activities of alanine aminotransferase (ALT), alkaline phosphatase (ALP), and gamma-glutamyl transpeptidase (GGT). These beneficial effects of BPHs were confirmed by histological findings in the hepatic and pancreatic tissues of diabetic rats. Indeed, they avoid lipid accumulation in the hepatocytes and protect the pancreatic β-cells from degeneration. Overall, the findings of the current study indicate that BPHs significantly attenuated hyperglycemia and hyperlipidemia in AIDR. The antioxidant activities of protein hydrolysates at different concentrations were evaluated using various in vitro antioxidant assays, including 1,1-diphenyl-2-picrylhydrazyl (DPPH.) radical method, reducing power assay, chelating activity, β-carotene bleaching and DNA nicking assay. All protein hydrolysates showed varying degrees of antioxidant activity. BPH-Z had the highest DPPH radical scavengingactivity (95% at 40 mg/ml) and higher ability to prevent bleaching of β-carotene than BPH-S and BPH-A21 (p<0.05). However, BPH-S exhibited the highest metal chelating activity (76,24% at 0,4 mg/ml) and the strongest protection against hydroxyl radical induced DNA breakage (p<0.05)

Analysis of the Cultivable Endophytic Bacterial Diversity in the Date Palm (Phoenix dactylifera L.) and Evaluation of Its Antagonistic Potential against Pathogenic Fusarium Species that Cause Date Palm Bayound DiseaseAnalysis of the Cultivable Endophytic

Abstract Biological control still remains an unexploited issue in southern countries such as Tunisia. Thus, the present study focused on the diversity of cultivable endophytic bacteria in the internal tissues (roots and leaves) of Tunisian date palm trees (Phoenix dactylifera L.). In order to assess their antagonistic potential towards date palm pathogens, particularly Fusarium. Indeed, the Genus Fusarium includes the causative agent of the Bayound disease, Fusarium oxysporum, a major treat for date production North Africa. Twenty two bacterial isolates presenting distinct colony morphology on TSA media were selected. The latter were characterized using Gram staining, biochemical tests, and molecular identification techniques based on 16S rRNA gene sequencing. Cultivable endophytic isolates were assigned into seven distinct groups. The species Arthrobacter agilis and Bacillus subtilis exhibited lasting antagonistic properties against a range of Fusarium species including the causing agent of the Bayoud disease, thus demonstrating their strong potential for future applications in the inoculation of date palm trees for biocontrol purposes. The isolates showed extracellular enzymatic activity including cellulase (76, 92%), protease (69, 23%) and amylase (38, 46%). This study thus demonstrates for the first time that the diversity of endophytic bacteria is abundant in date palm trees (Phoenix dactylifera L.) and could present varying biotechnological applications and particularly disease control

Analysis of the Cultivable Endophytic Bacterial Diversity in the Date Palm (Phoenix dactylifera L.) and Evaluation of Its Antagonistic Potential against Pathogenic Fusarium Species that Cause Date Palm Bayound Disease

International audienceBiological control still remains an unexploited issue in southern countries such as Tunisia. Thus, the present study focused on the diversity of cultivable endophytic bacteria in the internal tissues (roots and leaves) of Tunisian date palm trees (Phoenix dactylifera L.). In order to assess their antagonistic potential towards date palm pathogens, particularly Fusarium. Indeed, the Genus Fusarium includes the causative agent of the Bayound disease, Fusarium oxysporum, a major treat for date production North Africa. Twenty two bacterial isolates presenting distinct colony morphology on TSA media were selected. The latter were characterized using Gram staining, biochemical tests, and molecular identification techniques based on 16S rRNA gene sequencing. Cultivable endophytic isolates were assigned into seven distinct groups. The species Arthrobacter agilis and Bacillus subtilis exhibited lasting antagonistic properties against a range of Fusarium species including the causing agent of the Bayoud disease, thus demonstrating their strong potential for future applications in the inoculation of date palm trees for biocontrol purposes. The isolates showed extracellular enzymatic activity including cellulase (76, 92%), protease (69, 23%) and amylase (38, 46%). This study thus demonstrates for the first time that the diversity of endophytic bacteria is abundant in date palm trees (Phoenix dactylifera L.) and could present varying biotechnological applications and particularly disease control