In this work, response surface optimization strategy was employed to enhance the biodegradation process of fresh palm oil mill effluent (POME) by Aspergillus niger and Trichoderma virens. A central composite design (CCD) combined with response surface methodology (RSM) were employed to study the effects of three independent variables: inoculum size (%), agitation rate (rpm) and temperature (°C) on the biodegradation processes and production of biosolids enriched with fungal biomass protein. The results achieved using A. niger were compared to those obtained using T. virens. The optimal conditions for the biodegradation processes in terms of total suspended solids (TSS), turbidity, chemical oxygen demand (COD), specific resistance to filtration (SRF) and production of biosolids enriched with fungal biomass protein in fresh POME treated with A. niger and T. virens have been predicted by multiple response optimization and verified experimentally at 19% (v/v) inoculum size, 100 rpm, 30.2°C and 5% (v/v) inoculum size, 100 rpm, 33.3°C respectively. As disclosed by ANOVA and response surface plots, the effects of inoculum size and agitation rate on fresh POME treatment process by both fungal strains were significant.
Phylloplane microbes have been studied as strategic tools in management against plant pathogens. Non-pathogenic bacteria and fungi have been applied as crop protectants against various plant diseases. The present study aimed at evaluating the potentiality of Aspergillus niger spores in altering the activity of four key enzymes related to defense in tomato. The experiment was designed such that two groups of 50 tomato plants were considered: group 1 – sprayed with autoclaved distilled water (control) and group 2 – sprayed with A. niger spores. Spraying was carried out under aseptic conditions. The experimental parameters included analysis of the activity of peroxidase (POX), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) as well as expression of POX and PPO isoforms. The results demonstrated an inductive effect of A. niger on the activity of POX, PPO, PAL and TAL. Enhanced expression of POX and PPO isoforms was also observed. The results indicated that A. niger can be considered probiotic for the management of tomato against its phytopathogens.
Root associated bacteria were isolated from Suaeda nudiflora and two isolates were selected for this study: rhizospheric Bacillus megaterium and endophytic Pseudomonas aeruginosa. These isolates were inoculated into maize variety Narmada Moti during its germination. TTC (2, 3, 5-triphenyl tetrazolium chloride) staining was used to confirm the association of the isolates with the maize root. The effects of these root associated bacteria were tested alone and in combinations for cell wall reinforcement and the induction of defense enzymes such as phenylalanine ammonia lyase (PAL) and β-1,3-glucanase in the presence of fungal pathogen Aspergillus niger in maize. The results indicated that the rhizospheric bacteria had a greater fight response to fungal infection than the endophhytic bacteria due to cell wall lignification as well as the rapid induction of higher concentrations of defense related enzymes.