| Summary: | The nutrients availability for the plants is a determining factor for their development and growth. Phosphorus is an essential compound to plants, it is necessary to perform photosynthesis, respiration, gene transfer and reproduction. An alternative mechanism to the use of chemical fertilizers for increasing the cultures productivity on the soil phosphorus deficiency is the use of biotechnology by mainly biological processes occurring in the system soil/plant realized by phosphorus solubilizing microorganisms (PSM). Therefore, the objective of this study was to evaluate the phosphorus biossolubilization process from phosphate rock concentrate by Trichoderma harzianum in air-lift bioreactor employing reactive medium recycle. During 6 days was evaluated the phosphorus biossolubilization process by Trichoderma harzianum in air-lift reactor employing ascending air 0.5 vvm (volumetric flow per minute) and reaction medium recycle containing phosphate rock concentrated (5 g/L). Phosphorus biossolubilization by Trichoderma harzianum in air-lift reactor only with upward aeration (0.5 vvm) showed maximum solubilization equal to 212.19 ppm (27.23%), followed by 98,18% of glucose consumption and total acid concentration equal to 1.25 µmol/ml (0.5 µmol/ml of lactic acid, and 0.73 µmol/ml of acetic acid) in the fifth process day at 28 ± 0,5°C. By employing reaction medium recycle flow of 200 mL/min in air-lift reactor with aeration of 0.5 vvm at 28 ± 0.5°C, initial cell inoculum concentration equal to 3.5 ± 0.5 g/L and 5 g/L of phosphate rock concentrate and glucose was obtained on the third day of process 244.9 ppm (31.42% solubilization) of soluble phosphorus. By increasing the volumetric flow rate of recycle to 400 ml/min maintaining the same conditions, in the fourth day was reached 216.1 ppm (27.73% solubilization) of soluble phosphorus and 8.2 µmol/ml of organic acids (lactic and acetic). Comparing the results achieved between the three phosphorus biossolubilization process from phosphate rock concentrate in air-lift reactor by Trichoderma harzianum was observed that by employing recycle of reactive medium at 200 mL/min associated with compressed air flow at 0.5 vvm was obtained for a shorter period (3 days) a higher concentration of phosphorus soluble in a liquid medium (244.9 ppm). Indicative of the positive influence of the reactive medium recycle in the phosphorus availability process by Trichoderma harizianum from the production of organic acids using glucose as substrate.
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