Clay chips and beads capture in situ barley root microbiota and facilitate in vitro long-term preservation of microbial strains.

Capturing the diverse microbiota from healthy and/or stress resilient plants for further preservation and transfer to unproductive and pathogen overloaded soils, might be a tool to restore disturbed plant-microbe interactions. Here, we introduce Aswan Pink Clay as a low-cost technology for capturing and storing the living root microbiota. Clay chips were incorporated into the growth milieu of barley plants and developed under gnotobiotic conditions, to capture and host the rhizospheric microbiota. Afterward, it was tested by both a culture-independent (16S rRNA gene metabarcoding) and -dependent approach. Both methods revealed no significant differences between roots and adjacent clay chips in regard total abundance and structure of the present microbiota. Clay shaped as beads adequately supported the long-term preservation of viable pure isolates of typical rhizospheric microbes, i.e. Bacillus circulans, Klebsiella oxytoca, Sinorhizobium meliloti, and Saccharomyces sp., up to 11 months stored at -20°C, 4°C, and ambient temperature. The used clay chips and beads have the capacity to capture the root microbiota and to long-term preserve pure isolates. Hence, the developed approach is qualified to build on it a comprehensive strategy to transfer and store complex and living environmental microbiota of rhizosphere toward biotechnological application in sustainable plant production and environmental rehabilitation.

A novel plant-based-sea water culture media for in vitro cultivation and in situ recovery of the halophyte microbiome.

The plant-based-sea water culture medium is introduced to in vitro cultivation and in situ recovery of the microbiome of halophytes. The ice plant (Mesembryanthemum crystallinum) was used, in the form of juice and/or dehydrated plant powder packed in teabags, to supplement the natural sea water. The resulting culture medium enjoys the combinations of plant materials as rich source of nutrients and sea water exercising the required salt stress. As such without any supplements, the culture medium was sufficient and efficient to support very good in vitro growth of halotolerant bacteria. It was also capable to recover their in situ culturable populations in the phyllosphere, ecto-rhizosphere and endo-rhizosphere of halophytes prevailing in Lake Mariout, Egypt. When related to the total bacterial numbers measured for Suaeda pruinosa roots by quantitative-PCR, the proposed culture medium increased culturability (15.3-19.5%) compared to the conventional chemically-synthetic culture medium supplemented with (11.2%) or without (3.8%) NaCl. Based on 16S rRNA gene sequencing, representative isolates of halotolerant bacteria prevailed on such culture medium were closely related to Bacillus spp., Halomonas spp., and Kocuria spp. Seed germination tests on 25-50% sea water agar indicated positive interaction of such bacterial isolates with the germination and seedlings' growth of barley seeds.

Bio-preparates support the productivity of potato plants grown under desert farming conditions of north Sinai: Five years of field trials.

Organic agriculture as well as good agricultural practices (GAPs) intrigues the concern of both consumers and producers of agricultural commodities. Bio-preparates of various rhizospheric microorganisms (RMOs) are potential sources of biological inputs supporting plant nutrition and health. The response of open-field potatoes to the application of RMO bio-preparates, the biofertilizer "Biofertile" and the bioagent "Biocontrol", were experimented over 5 successive years under N-hunger of north Sinai desert soils. Both vegetative and tuber yields of a number of tested cultivars were significantly improved due to rhizobacterial treatments. In the majority of cases, the biofertilizer "Biofertile" did successfully supply ca. 50% of plant N requirements, as the yield of full N-fertilized plants was comparable to those received 50% N simultaneously with bio-preparates treatment. The magnitude of inoculation was cultivar-dependent; cvs. Valor and Oceania were among the most responsive ones. Bio-preparate introduction to the plant-soil system was successful via soaking of tubers and/or spraying the plant canopy. The "Biocontrol" formulation was supportive in controlling plant pathogens and significantly increased the fruit yields. The cumulative effect of both bio-preparates resulted in tuber yield increases of ca. 25% over control.