Isolation and Characterization of a New Endophytic Actinobacterium Streptomyces californicus Strain ADR1 as a Promising Source of Anti-Bacterial, Anti-Biofilm and Antioxidant Metabolites

Abstract

In view of the fast depleting armamentarium of drugs against significant pathogens, like methicillin-resistant Staphylococcus aureus (MRSA) and others due to rapidly emerging drug-resistance, the discovery and development of new drugs need urgent action. In this endeavor, a new strain of endophytic actinobacterium was isolated from the plant Datura metel, which produced secondary metabolites with potent anti-infective activities. The isolate was identified as Streptomyces californicus strain ADR1 based on 16S rRNA gene sequence analysis. Metabolites produced by the isolate had been investigated for their antibacterial attributes against important pathogens: S. aureus, MRSA, S. epidermis, Enterococcus faecium and E. faecalis. Minimum inhibitory concentration (MIC90) values against these pathogens varied from 0.23 ± 0.01 to 5.68 ± 0.20 μg/mL. The metabolites inhibited biofilm formation by the strains of S. aureus and MRSA (Biofilm inhibitory concentration [BIC90] values: 0.74 ± 0.08–4.92 ± 0.49 μg/mL). The BIC90 values increased in the case of pre-formed biofilms. Additionally, the metabolites possessed good antioxidant properties, with an inhibitory concentration (IC90) value of 217.24 ± 6.77 µg/mL for 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging. An insight into different classes of compounds produced by the strain ADR1 was obtained by chemical profiling and GC-MS analysis, wherein several therapeutic classes, for example, alkaloids, phenolics, terpenes, terpenoids and glycosides, were discovered.

Marine Actinomycetes, New Sources of Biotechnological Products

“…Such anti-biofilm agents would make the evolution of resistance to antimicrobial products less likely, since the selection pressure is “softer”. In one study, metabolites of Streptomyces californicus strain ADR1 inhibited biofilm formation in Staphylococcus aureus [ 195 ]. Among 101 strains of Streptomyces and rare actinomycetes collected from sea sediments in the Andaman Sea and the Gulf of Thailand, 10 and 13 strains inhibited at least 60% of the biofilm formation of Escherichia coli and Staphylococcus aureus , respectively [ 196 ].…”

Bioprospecting of endophytes in medicinal plants of Thar Desert: An attractive resource for biopharmaceuticals

“…Secondary metabolites obtained from chloroformic fungal extract of Aspergillus fumigatus , an endophytic fungus reported from M. oleifera demonstrated an effective antibiofilm activity towards several pathogenic microbes [ 159 , 181 ]. Singh and Dubey [ 183 ] reported potent antibiofilm activity of secondary metabolites isolated from the crude extract of a novel strain of endophytic actinobacterium i.e . Streptomyces californicus strain ADR1 recovered from the D. metel , against the strain of S. aureus [ 183 ].…”

“…Singh and Dubey [ 183 ] reported potent antibiofilm activity of secondary metabolites isolated from the crude extract of a novel strain of endophytic actinobacterium i.e . Streptomyces californicus strain ADR1 recovered from the D. metel , against the strain of S. aureus [ 183 ].…”

Impact of Sugar Type Addition and Fermentation Temperature on Pomegranate Alcoholic Beverage Production and Characteristics

“…Determination of free radical-scavenging activity (FRSA) through DPPH• inhibition represents the most common method for determination of antioxidant activity in plant materials, including pomegranate [30]. It is also a convenient method for evaluation of the antioxidant activity of fermented products [31][32][33]. Due to the fact that many studies on pomegranate and other fruit juices have utilized this method, for such measurements [15,[34][35][36] or even in combination with other methods [37,38], it was adopted in the present work in order to facilitate comparisons with relevant literature information.…”