Evaluation of the growth medium of a new ice-nucleating-active Pseudomonas: A response surface methodology approach

Aims@#Attention to ice nucleation proteins has increased for more than two decades. Ice nucleation proteins have been utilized for artificial snow-making known as Snowmax™, cryopreservation of tissues and cells, and cloud condensation nuclei. There is a direct relationship between bacterial growth and ice nucleation activity. Therefore, the optimization of the culture medium seems necessary.@*Methodology and results@#The effect of different carbon and nitrogen sources on the growth of a new native Pseudomonas sp. IRL.INP1 was evaluated by using fractional factorial design, the path of the steepest ascent experiment and central composite design. Ice nucleation activity, biomass and whole-cell protein were identified afterward. The model predicted by response surface methodology indicated that the maximum bacterial growth was observed when sucrose, ammonium sulfate [(NH4)2SO4] and manganese (II) (Mn2+) were utilized at 12.46 g/L, 321.97 mg/L and 938.09 µM, respectively. Also, 1.10 g/L biomass and 0.85 µg/µL whole-cell proteins were gained, and the isolate showed ice nucleation activity 31 sec sooner after optimization.@*Conclusion, significance and impact of study@#Ice nucleation proteins are growth-dependent and the growth condition optimization leads to higher bacterial cells growth. Therefore, best bacterial growth was obtained when proper carbon and nitrogen sources were used, and ice nucleation activity was observed in shorter time. This is the first study concerning ice nucleation activity optimization using different carbon and nitrogen sources.

[Isolation and identification of a type strain bacteria with the highest ability to produce organophosphorus acid anhidrase]

In Iran, Organ phosphorus pesticides such as chloropyrifos and diazinon are widely used in agriculture. These compounds inhibit activity of cholinesterase in nearly irreversible manner resulting in malfunction of nerve impulse transmission. This result in humans can produce illness or even death. Therefore, the present study aims to isolate various bacterial strains in specified contaminated regions. We selected one of the isolates that contain the highest OP-hydrolyzing capability for using such strain, in decontaminating environmentally harmful OP residues. In this study, vast waters from chemical factories and contaminated agricultural soil samples were used for isolation of several bacterial strains that contain OPAA enzyme are capable of utilizing chloropyrifos and diazinon as a source of carbon and phosphorus by selective enrichment on mineral salt medium [MSM], which contains chloropyrifos or diazinon. One strain was selected for analysis of degradation ability with growth studies and HPLC technique and characterization by Bergey's manual. From vast water and soil, ten bacterial strains were isolated using chloropyrifos and diazinon as source of carbon and phosphorus. One of them named IHU strain4; grows most rapidly and luxuriously and displays the highest organophosphate-hydrolyzing capability. On the basis of morphological and biochemical characteristics, the bacterial isolate was identified as a member of the genus pseudomonas. From these findings, it can be concluded that the isolated bacterial strain is able to utilize Organ phosphorus pesticides as a source of carbon and phosphorus. Utilization of these compounds by soil microorganisms is a crucial phenomenon by which these compounds are removed from the environment, thus, preventing environmental pollution. Results from the present study suggest that the isolated bacterial strain may be used for remediation of pesticide-contamination