Plant Beneficial Endophytic Bacteria from the Ethnomedicinal Mussaenda roxburghii (Akshap) of Eastern Himalayan Province, India

Mussaenda roxburghii are very important ethnomedicinal plant, used for its various applications from the ancient period. The role of their associated plant beneficial endophytic bacteria was evaluated, which were previously untapped. Among the isolates, PAK6 was identified as efficient phosphate solubilizer, quantified by the molybdenum blue method. Four isolates PAK1, PAK2, PAK3, and PAK8 were able to synthesize significant level of IAA in the presence and absence of tryptophan. Isolates PAK1 and PAK9 were able to produce siderophore on CAS agar media, PAK2 and PAK9 were able to produce HCN, and PAK7 and PAK8 were able to grow on N2-free medium. All the isolates were able to produce a moderate level of polysaccharide and tolerate up to 10% of NaCl. Isolates PAK3, PAK6, PAK7, and PAK8 were able to grow well at pH 5.0 and isolates PAK2, PAK7, and PAK8 were able to tolerate 600 μg mL−1 of Al+3, while all the isolates except PAK1 showed a tolerance to 600 μg mL−1 of Mn+2 tested. Endophytic bacterial isolates PAK6 and PAK9 were effective against Sclerotinia sclerotiorum and Sclerotium rolfsii