Screening and increase of exopolysaccharide production by rhizobial strains, stress tolerances and its efficiency with "in Vivo" peanut plants | ||||
| Egyptian Journal of Agricultural Research | ||||
| Article 2, Volume 100, Issue 1, March 2022, Page 11-21 PDF (1.06 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/ejar.2022.106075.1171 | ||||
 View on SCiNiTO | ||||
| Authors | ||||
Amal A. Ali; Heba O.M. Orf  
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| Soil, Water and Environment Research Institute, Agricultural Research Center, Giza, Egypt | ||||
| Abstract | ||||
| Five rhizobial strains were screened to explore exopolysaccharide (EPS) production. Maximum EPS production was shown by R. leguminosarum bv. viciae (Bani sweef) at 5.48 g L-1, followed by Bradyrhizobium sp. (strain ARC 617) at 5.2 g L-1. EPS production was enhanced by 7.52 and 7.2 g L-1 by castor oil followed by olive oil, which gave 7.08 and 6.56 g L-1 in R. leguminosarum bv. viciae (Bani sweef) and Bradyrhizobium sp. (strain ARC 617), respectively, as compared to YEM media. The maximum level of EPS production was reached at pH 6, followed by pH 7. The optimum inoculum amount for maximum EPS production was discovered to be 2% inoculum. Exopolyssacharides-producing bacteria were tested in vitro for their ability to withstand various biotic and abiotic stresses. Selected rhizobia and bradyrhizobia grown on modified YEM media resistance salinity and had higher cell log counts than those grown on YEM media. Moreover, the EPSs of rhizobia and bradyrhizobia grown on modified YEM media may have a preventive role against the impacts of heavy metals where they are more tolerant to heavy metals than those of YEM media. Concerning antibiotics, R. leguminosarum bv. viciae based on YEM modified media resistance to the seven antibiotics, while Bradyrhizobium sp. resistance all antibiotics except oxytetracycline and streptomycin. The data from the pot experiment suggested that inoculation with EPS producing bacteria based on modified media increased plant height, the shoots' dry weight, nitrogen content, chlorophyll a, b, and total chlorophyll as compared to other treatments. | ||||
| Keywords | ||||
| Exopolysaccharide; rhizobia; cultural optimization; antibiotics; heavy metals | ||||
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