Studies on Antibacterial Activity and Diversity of Cultivable Actinobacteria Isolated from Mangrove Soil in Futian and Maoweihai of China

Abstract

Mangrove is a rich and underexploited ecosystem with great microbial diversity for discovery of novel and chemically diverse antimicrobial compounds. The goal of the study was to explore the pharmaceutical actinobacterial resources from mangrove soil and gain insight into the diversity and novelty of cultivable actinobacteria. Consequently, 10 mangrove soil samples were collected from Futian and Maoweihai of China, and the culture-dependent method was employed to obtain actinobacteria. A total of 539 cultivable actinobacteria were isolated and distributed in 39 genera affiliated to 18 families of 8 orders by comparison analysis of partial 16S rRNA gene sequences. The dominant genus was Streptomyces (16.0 %), followed by Microbacterium (14.5 %), Agromyces (14.3 %), and Rhodococcus (11.9 %). Other 35 rare actinobacterial genera accounted for minor proportions. Notably, 11 strains showed relatively low 16S rRNA gene sequence similarities (< 98.65 %) with validly described species. Based on genotypic analyses and phenotypic characteristics, 115 out of the 539 actinobacterial strains were chosen as representative strains to test their antibacterial activities against “ESKAPE” bacteria by agar well diffusion method and antibacterial mechanism by the double fluorescent protein reporter system. Fifty-four strains in 23 genera, including 2 potential new species, displayed antagonistic activity in antibacterial assay. Meanwhile, 5 strains in 3 genera exhibited inhibitory activity on protein biosynthesis due to ribosome stalling. These results demonstrate that cultivable actinobacteria from mangrove soil are potentially rich sources for discovery of new antibacterial metabolites and new actinobacterial taxa.

From Isolation of Phosphate Solubilizing Microbes to Their Formulation and Use as Biofertilizers: Status and Needs

“…Actinobacteria play an important role in soil and in plant interaction because of their ability to produce a large number of secondary metabolites, many of which possess antibacterial activity (Lazzarini et al, 2000). Actinobacteria produce approximately two-thirds of the known antibiotics produced by all microorganisms (Dhanasekaran et al, 2012;Feina et al, 2019). This nutrient cycling capacity makes them an ideal candidate for natural fertilizers (Jog et al, 2016;Olanrewaju and Babalola, 2019).…”

Isolation, Classification and Antagonistic Properties of Alkalitolerant Actinobacteria from Algerian Saharan Soils

“…Actinobacteria are a group of microorganisms that are wide spread in nature and are able to occupy diverse habitats such as soils (Li et al 2019), plants tissues (Chankharnhaengdecha et al 2013), lichens (Yamamura et al 2011) and extreme aquatic and terrestrial ecosystems (Dhakal et al 2017;Goodfellow et al 2018;Idris et al 2017). Extremophilic actino bacteria can be divided into acidophilic (Golinska et al 2016), alkaliphilic (Sel ya nin et al 2005; Thumar et al 2010), haloalka liphilic (Gohel and Singh 2018), halophilic (Al- Tai and Ruan 1994;Chun et al 2000 ;Hamedi et al 2013;Meldat et al 2011Meldat et al , 2013, psychrophilic (Miinnisto et al 2000), thermophilic (Zhou et al 2012) and xerophilic (Montero-Calasanz et al 2012) groups.…”

Exploitation of Potentially New Antibiotics from Mangrove Actinobacteria in Maowei Sea by Combination of Multiple Discovery Strategies

“…Actinobacteria are widely dispersed throughout the mangrove environments [34,37,38,[41][42][43][44][45][46]. In this study, to investigate actinobacterial biodiversity and harvest more potentially antibacterial strains, eight mangrove soil samples from different sites of Maowei Sea Mangrove Reserve were collected.…”

“…Actinobacteria were isolated by using the dilution plating technique, as described by Li et al [38]. A volume of 0.2 mL of 10 −2 (g/mL) soil suspension was spread onto isolation agar plates.…”

“…In the recent decade, studies on mangrove derived actinomycetes and their secondary metabolites have become a hotspot to discover new antibiotics. To date, at least 88 new actinobacterial species, including eight novel genera, have been isolated from mangrove, and more than 80 new compounds including some promising molecules such as salinosporamide A, halichoblelide D, xiamycins, and indolocarbazoles have been reported from mangrove-derived actinobacteria [27,[32][33][34][35][36][37][38].…”