Plant-based culture media: Efficiently support culturing rhizobacteria and correctly mirror their in-situ diversity

Abstract

Our previous publications and the data presented here provide evidences on the ability of plant-based culture media to optimize the cultivability of rhizobacteria and to support their recovery from plant-soil environments. Compared to the tested chemically-synthetic culture media (e.g. nutrient agar and N-deficient combined-carbon sources media), slurry homogenates, crude saps, juices and powders of cactus (Opuntia ficus-indica) and succulent plants (Aloe vera and Aloe arborescens) were rich enough to support growth of rhizobacteria. Representative isolates of Enterobacter spp., Klebsiella spp., Bacillus spp. and Azospirillum spp. exhibited good growth on agar plates of such plant-based culture media. Cell growth and biomass production in liquid batch cultures were comparable to those reported with the synthetic culture media. In addition, the tested plant-based culture media efficiently recovered populations of rhizobacteria associated to plant roots. Culturable populations of >106–108 cfu g−1 were recovered from the ecto- and endo-rhizospheres of tested host plants. More than 100 endophytic culture-dependent isolates were secured and subjected to morphophysiological identification. Factor and cluster analyses indicated the unique community structure, on species, genera, class and phyla levels, of the culturable population recovered with plant-based culture media, being distinct from that obtained with the chemically-synthetic culture media. Proteobacteria were the dominant (78.8%) on plant-based agar culture medium compared to only 31% on nutrient agar, while Firmicutes prevailed on nutrient agar (69%) compared to the plant-based agar culture media (18.2%). Bacteroidetes, represented by Chryseobacterium indologenes, was only reported (3%) among the culturable rhizobacteria community of the plant-based agar culture medium.

Plant powder teabags: a novel and practical approach to resolve culturability and diversity of rhizobacteria

“…Consistent with our previous findings, the tested plant teabag culture media remarkably supported recovery of in situ endo‐rhizobacteria associated with roots of clover and maize (Nour et al , Youssef et al ). The significant increase in culturability was most likely related to the development of microcolonies with prolonged incubation time, representing 32–77% of the total CFUs developed on plant teabags compared with 14–31% on standard chemically synthetic agar media.…”

“…Our previous publications (Nour et al , Youssef et al ) provided original results and evidences on the ability of crude plant slurry homogenates, juices and saps, without any supplements, to support culturability of rhizobacteria and retrieval of their in situ populations. For ease of application and practicability, this study introduces dehydrated powders of plants ( Trifolium alexandrinum and Paspalum vaginatum ) packed in teabags to prepare liquid infusions rich enough to cultivate endo‐rhizobacteria.…”

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

“…Our previous publications [16] , [17] provided original results and evidences on the ability of crude plant slurry homogenates, juices and saps, as such without any supplements, to support culturability of rhizobacteria and to retrieve their in situ populations. For ease of application, plant dehydrated powders packed in teabags were used to prepare liquid infusions rich enough to cultivate rhizobacteria [18] .…”

An inoculum-dependent culturing strategy (IDC) for the cultivation of environmental microbiomes and the isolation of novel endophytic Actinobacteria

“…To gain insights into their unknown functions and exploit their potentials, different approaches were recently introduced to culture such not-yet-cultured bacteria [2,3]. In this respect, the plantonly-based culture media were presented as natural culture media to replace myriad formulas of synthetic culture media, and strongly recommended to increase the cultivability of the plant microbiota [4][5][6][7][8][9][10]. To alleviate the stress of disproportionate nutrients, present in common culture media, we aimed at culturing maize and sunflower microbiota on the natural nutrients present in the plant inoculum itself, compared to highly diluted plant-only-based culture media and standard R2A.…”