Optimization of Extracellular Keratinase Production by Aspergillus terreus Isolated from Chicken's Litter

In this current study 45 fungal isolates were isolated from chicken's litter on Feather Agar Medium (FAM) were screened for determining the potent keratinase producing isolates. Out of these fungal isolates, twelve species and one species variety exhibited various degrees of keratinolytic activities from which A. terreus showed the highest keratinase production (12.6U/ml). The optimum temperature and initial pH for keratinase production by A. terreus were 40°C and 8, respectively. The highest keratinase production was observed for a period 25 days. The optimum ionic strength for the enzyme production was 80mM NaCl. Deprivation of K+, Fe2+, Mg2+, Ca2+ or Zn2+ from the culture medium drastically reduced the keratinase production by A. terreus. In contrast, sulfur deprivation did not significantly affect the keratinase production. The Km and Vmax values for A. terreus keratinase were 8.64mg keratin and 56.7U/mg proteins, respectively. The optimum temperature, pH and ionic strength for keratinase activity were 35°C, 7.8 and 80-100mM NaCl, respectively

Bioconversion of plant wastes to β-carotene by Rhodotorula glutinis KU550702

Microbial synthesis of β-carotene has gained more interest as an alternative to synthetic β-carotene due to easy extraction and high yield. The vitamin microbial production is mainly dependent on culture conditions and the medium compositions. In this study, the β-carotene production by the Rhodo-torula glutinis ASU6 (KU550702) was evaluated under different growth conditions and nutrient composition. Different agro-renewable wastes were tested as carbon source for R. glutinis to obtain maximum amount of β-carotene. Meanwhile, it is clear that R. glutinis could grow well on acid extract of onion peels and produced large amount of β-carotene. Initial statistical screening using a Plackett-Burman design showed temperature, incubation time, fermentation type, non-treated onion waste, KH2PO4 and L-asparagine as significantly, influencing β-carotene production. Response surface methodology was applied to determine the mutual interactions between these parameters and optimal levels for β-carotene production. The maximum value of β-carotene production was 204.29 mg/l (7.5-fold) of value observed as central point of the central composite design. All the experimental data are in good agreement with predicted ones, confirming the responsibility of the proposed empirical model in describing β-carotene production by R. glutinis. In the whole, the outcomes of this study support the exploitation of onion peels through microbial fermentation for β-carotene production

Bioconversion of plant wastes to β-carotene by Rhodotorula glutinis KU550702

Microbial synthesis of β-carotene has gained more interest as an alternative to synthetic β-carotene due to easy extraction and high yield. The vitamin microbial production is mainly dependent on culture conditions and the medium compositions. In this study, the β-carotene production by the Rhodo-torula glutinis ASU6 (KU550702) was evaluated under different growth conditions and nutrient composition. Different agro-renewable wastes were tested as carbon source for R. glutinis to obtain maximum amount of β-carotene. Meanwhile, it is clear that R. glutinis could grow well on acid extract of onion peels and produced large amount of β-carotene. Initial statistical screening using a Plackett-Burman design showed temperature, incubation time, fermentation type, non-treated onion waste, KH2PO4 and L-asparagine as significantly, influencing β-carotene production. Response surface methodology was applied to determine the mutual interactions between these parameters and optimal levels for β-carotene production. The maximum value of β-carotene production was 204.29 mg/l (7.5-fold) of value observed as central point of the central composite design. All the experimental data are in good agreement with predicted ones, confirming the responsibility of the proposed empirical model in describing β-carotene production by R. glutinis. In the whole, the outcomes of this study support the exploitation of onion peels through microbial fermentation for β-carotene production

Evaluation of Native Bacterial Isolates for Control of Cucumber Powdery Mildew under Greenhouse Conditions

Cucumber plants are often attacked by various pathogens, which can considerably decrease production and cause significant losses. One of the most prevalent fungal diseases is powdery mildew, caused by an obligate pathogen, Podosphaera xanthii. It is a serious disease that causes significant damage to the whole plant, i.e., leaves, fruits, and stems, under both greenhouse and field conditions. The main objective of this result is to assess the effectiveness of Bacillus spp. against cucumber powdery mildew under in vitro and in vivo conditions. Treatment with B. licheniformis and B. aerius culture filtrates reduced the conidial germination of the pathogen by 60 and 85%, respectively. Under greenhouse conditions, spraying cucumber plants with both microorganisms was effective at reducing powdery mildew disease severity. High reductions of disease severity were achieved by treatment of B. licheniformis as a cell suspension and B. aerius strain as culture filtrate, 45.3 and 77.3%, respectively, two days before inoculation. Additionally, treatment with these bacterial strains resulted in a significant increase in the fresh and dry weights of the cucumber plants. The highest increase of fresh and dry weight was found with B. licheniformis CS and B. aerius strain CF treatment at two days before or after infection. After treatment with the bioagents, the content of total phenols, polyphenol oxidase, and peroxidase was enhanced in treatment plants. The use of B. licheniformis and B. aerius as foliar sprays significantly induced resistance to P. xanthii in cucumber plants and stimulated many biochemical functions. Therefore, we propose B. licheniformis and B. aerius as an effective alternative to harmful chemicals

Evaluation of Native Bacterial Isolates for Control of Cucumber Powdery Mildew under Greenhouse Conditions

Cucumber plants are often attacked by various pathogens, which can considerably decrease production and cause significant losses. One of the most prevalent fungal diseases is powdery mildew, caused by an obligate pathogen, Podosphaera xanthii. It is a serious disease that causes significant damage to the whole plant, i.e., leaves, fruits, and stems, under both greenhouse and field conditions. The main objective of this result is to assess the effectiveness of Bacillus spp. against cucumber powdery mildew under in vitro and in vivo conditions. Treatment with B. licheniformis and B. aerius culture filtrates reduced the conidial germination of the pathogen by 60 and 85%, respectively. Under greenhouse conditions, spraying cucumber plants with both microorganisms was effective at reducing powdery mildew disease severity. High reductions of disease severity were achieved by treatment of B. licheniformis as a cell suspension and B. aerius strain as culture filtrate, 45.3 and 77.3%, respectively, two days before inoculation. Additionally, treatment with these bacterial strains resulted in a significant increase in the fresh and dry weights of the cucumber plants. The highest increase of fresh and dry weight was found with B. licheniformis CS and B. aerius strain CF treatment at two days before or after infection. After treatment with the bioagents, the content of total phenols, polyphenol oxidase, and peroxidase was enhanced in treatment plants. The use of B. licheniformis and B. aerius as foliar sprays significantly induced resistance to P. xanthii in cucumber plants and stimulated many biochemical functions. Therefore, we propose B. licheniformis and B. aerius as an effective alternative to harmful chemicals