Characterization and application of tannase and gallic acid produced by co-fungi of Aspergillus niger and Trichoderma viride utilizing agro-residues substrates.

Bioconversion using fungi, as natural factory of many applicable bioactive compounds, as enzymes utilizing agro-residue substrates as a solid, abundant, low-cost growth and enzyme production media. This study characterized and applied a tannase enzyme (308 U/mg) from Aspergillus niger A8 + Trichoderma viride co-cultures utilizing pomegranate peels. The partially purified enzyme showed maximal relative activity at 37-65 °C for 10 min and kinetics of thermal inactivation energy at a high point at 60 °C for 0.040/min. The half-life was 37 °C for 58.6 min, temperature coefficient Q10 of tannase was maximal for 1.38 between 40 and 50 °C, and the activation energy was 17.42 kJ/mol. The enzyme activity peaked in the pH range of 4-8, and the maximum relative activity (100.6%) for tannase was achieved at pH 6. The Km and Vmax values for purified enzymes using tannic acid were 7.3 mg/mL and 3333.33 U/mL, respectively. The enzyme reduced the total tannin content in all tannin-rich substrates after 12h. The gallic acid (GA) had total phenols of 77.75 ppm and antioxidant activity of 82.91%. It was observed that the GA as antimicrobial influencer exhibited the largest inhibitory zone diameter (IZD) of 31 ± 1.0 mm against Pseudomonas aeruginosa ATCC27853. The GA minimum inhibitory concentration value was ranged from 7770.0-121.41 µg/mL. The obtained GA showed a bactericidal effect against all bacterial strains except Shigella sonnei DSM5570 and Salmonella typhi DSM17058, which showed bacteriostatic behavior.

Plant growth-promoting microorganisms as biocontrol agents of plant diseases: Mechanisms, challenges and future perspectives.

Plant diseases and pests are risk factors that threaten global food security. Excessive chemical pesticide applications are commonly used to reduce the effects of plant diseases caused by bacterial and fungal pathogens. A major concern, as we strive toward more sustainable agriculture, is to increase crop yields for the increasing population. Microbial biological control agents (MBCAs) have proved their efficacy to be a green strategy to manage plant diseases, stimulate plant growth and performance, and increase yield. Besides their role in growth enhancement, plant growth-promoting rhizobacteria/fungi (PGPR/PGPF) could suppress plant diseases by producing inhibitory chemicals and inducing immune responses in plants against phytopathogens. As biofertilizers and biopesticides, PGPR and PGPF are considered as feasible, attractive economic approach for sustainable agriculture; thus, resulting in a "win-win" situation. Several PGPR and PGPF strains have been identified as effective BCAs under environmentally controlled conditions. In general, any MBCA must overcome certain challenges before it can be registered or widely utilized to control diseases/pests. Successful MBCAs offer a practical solution to improve greenhouse crop performance with reduced fertilizer inputs and chemical pesticide applications. This current review aims to fill the gap in the current knowledge of plant growth-promoting microorganisms (PGPM), provide attention about the scientific basis for policy development, and recommend further research related to the applications of PGPM used for commercial purposes.

Flavoring and extending the shelf life of cucumber juice with aroma compounds-rich herbal extracts at 4 °C through controlling chemical and microbial fluctuations.

This work aims to enhance the flavor of functional cucumber juice using herbal extracts of peppermint, basil, lavender, and lemongrass ethanolic extracts and extend its lifetime by controlling the chemical and microbial fluctuations. Cucumber juices were processed as; non-supplemented (J-Con), J-PME, J-BE, J-LE, and J-LEE supplemented with peppermint, basil, lavender, and lemongrass ethanolic extracts, respectively. Peppermint extract was significantly scavenged 88% of DPPH radicals and inhibited the growth of tested gram-positive, gram-negative bacteria and fungi followed by the lemongrass extract. The antioxidant activity of cucumber juices increased due to polyphenols and aroma compounds in the added extracts. However, the antioxidant content was decreased after two months of storage at 4 °C, due to the decrease in polyphenols. The flavor compounds were determined using GC mass, wherein hydrocarbons, acids, alcohols, and carbonyl compounds were the main aroma contents in cucumber juices, and their contents decreased with storage time. Peppermint and lemongrass extracts were significantly (p ≤ 0.05) increased the whiteness of J-PME, and J-LEE, respectively. The highest score of flavor and taste was observed in J-PME that scored 8.3 based on panelists' reports followed by J-LEE. The PME was significantly maintained 91% of the odor and color of J-PME as compared to other juices.

Exogenously applied nitrogenous fertilizers and effective microorganisms improve plant growth of stevia (Stevia rebaudiana Bertoni) and soil fertility.

The effects of different fertilizers and biofertilizers on crop production to increase plant growth, improve quality and yield components (dry leaves yield, leaf protein, and stevioside) of crops has been extensively studied. However, the combination of both types of fertilizers have rarely been investigated. To explore the effect of different fertilizers and biofertilizers on stevia plant, a two-year field experiment was conducted to investigate the growth response of stevia plants under the influence of nitrogenous fertilizers (NFs) and effective microorganisms (EM). The experiment was laid out in a split-plot design, with EM as the main plot factor (-EM and +EM) and NFs as the subplot factor [control, chemical NFs (Ch-N) and organic NFs (Org-N)]. The results showed that, plants treated with EM and Org-N showed 2-, 2.2-, 2.4-, 2.5-, 3.3- and 3-fold increases in plant height, number of branches, total leaf area, plant fresh weight, plant dry weight and leaf dry yield, respectively, compared to untreated plants. Similarly, plants receiving EM along with Ch-N showed 1.86-, 1.7-, 2.2-, 2.12-, 3-, and 2.72-fold increases in the same traits. Total chlorophyll, protein, N, P, K and sativoside contents were increased by 88.8, 152, 138, 151.5, 43 and 137.5% when EM and Org-N were applied to stevia plants. Application of EM together with Ch-N increased these properties by 0.5, 127.7, 115, 216, 42.6 and 83.8%, respectively in the same traits. Overall, the combined application of NFs and EM improved growth, yield and nutrient accumulation in stevia plants.

Biochemical and Functional Characterization of Kidney Bean Protein Alcalase-Hydrolysates and Their Preservative Action on Stored Chicken Meat.

A new preservation approach is presented in this article to prolong the lifetime of raw chicken meat and enhance its quality at 4 °C via coating with highly soluble kidney bean protein hydrolysate. The hydrolysates of the black, red, and white kidney protein (BKH, RKH, and WKH) were obtained after 30 min enzymatic hydrolysis with Alcalase (E/S ratio of 1:100, hydrolysis degree 25-29%). The different phaseolin subunits (8S) appeared in SDS-PAGE in 35-45 kD molecular weight range while vicilin appeared in the molecular weight range of 55-75 kD. The kidney bean protein hydrolysates have considerable antioxidant activity as evidenced by the DPPH-scavenging activity and ß-carotine-linolenic assay, as well as antimicrobial activity evaluated by disc diffusion assay. BKH followed by RKH (800 µg/mL) significantly (p ≤ 0.05) scavenged 95, 91% of DPPH and inhibited 82-88% of linoleic oxidation. The three studied hydrolysates significantly inhibited the growth of bacteria, yeast, and fungi, where BKH was the most performing. Kidney bean protein hydrolysates could shield the chicken meat because of their amphoteric nature and many functional properties (water and oil-absorbing capacity and foaming stability). The quality of chicken meat was assessed by tracing the fluctuations in the chemical parameters (pH, met-myoglobin, lipid oxidation, and TVBN), bacterial load (total bacterial count, and psychrophilic count), color parameters and sensorial traits during cold preservation (4 °C). The hydrolysates (800 µg/g) significantly p ≤ 0.05 reduced the increment in meat pH and TVBN values, inhibited 59-70% of lipid oxidation as compared to control during 30 days of cold storage via eliminating 50% of bacterial load and maintained secured storage for 30 days. RKH and WKH significantly (p ≤ 0.05) enhanced L*, a* values, thus augmented the meat whiteness and redness, while, BKH increased b* values, declining all color parameters during meat storage. RKH and WKH (800 µg/g) (p ≤ 0.05) maintained 50-71% and 69-75% of meat color and odor, respectively, increased the meat juiciness after 30 days of cold storage. BKH, RKH and WKH can be safely incorporated into novel foods.