Actinobacteria Isolated From Laminaria ochroleuca: A Source of New Bioactive Compounds

Abstract

Nature is the major reservoir of biologically active molecules. The urgent need of finding novel molecules for pharmaceutical application is prompting the research of underexplored environments, such as marine ecosystems. Here, we investigated cultivable actinobacteria associated with the macroalgae Laminaria ochroleuca and assessed their potential to produce compounds with antimicrobial or anticancer activities. A specimen of L. ochroleuca was collected in a rocky shore in northern Portugal, and fragments of tissues from different parts of the macroalgae (holdfast, stipe, and blades) were surface sterilized and plated in three culture media selective for actinobacteria. A total of 90 actinobacterial strains were isolated, most of which affiliated with the genus Streptomyces . Isolates associated with the genera Isoptericola , Rhodococcus , Nonomuraeae , Nocardiopsis , Microbispora , and Microbacterium were also obtained. Organic extracts from the isolates were tested for their antimicrobial activity using the agar-based disk diffusion method, followed by determination of minimum inhibitory concentration (MIC) values. Forty-five isolates inhibited the growth of Candida albicans and/or Staphylococcus aureus , with MIC values ranging from <0.5 to 1000 μg mL −1 . The actinobacterial isolates were also tested for their anticancer potential on two human cancer cell lines. Twenty-eight extracts affected the viability of at least one human cancer cell line (breast carcinoma T-47D and neuroblastoma SH-SY5Y) and non-carcinogenic endothelial cell line (hCMEC/D3). Seven extracts affected the viability of cancer cells only. This study revealed that L. ochroleuca is a rich source of actinobacteria with promising antimicrobial and anticancer activities and suggests that macroalgae may be a valuable source of actinobacteria and, consequently, of new molecules with biotechnological importance.

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

“…The MIC 90 values of the metabolites from some of the recently reported Streptomyces spp. against the strains of S. aureus and MRSA were in the ranges of 2–125 μg/mL [ 52 , 53 , 54 ], which indicated wide variation in the anti-bacterial potency of the metabolites. The results of the present study clearly demonstrated that the anti-bacterial potency of ADR1 metabolites appeared at the bottom of the range or even lower, validating its promising potential for discovery of drugs against priority pathogens.…”

Gastrointestinal Motility and Improvement Efficacy of Shenhuang Plaster Application on Shenque: Identification, Evaluation, and Mechanism

“…Certain bacteria which are beneficial in chemotherapy have been identified. For instance, Bacteroides [54], Deferribacteres [55], Tenericutes [56], and Actinobacteria [57] were indicated to be of beneficial for chemotherapy patients. At the genus level, Prevotellaceae_UCG-001 [58] and Rikenellaceae_RC9_gut_group [59] are involved in the degradation of carbohydrates and proteins to produce various organic acids.…”

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

“…These phytohormones have been tested on eggplant (Solanum melongena) and have improved the agronomic performance of the species. On the other hand, Endophytic Actinobacteria produces secondary metabolites that improve growth and resistance to various environmental stresses (Girão et al, 2019). For instance, kasugamycin and mildiomycin from Streptomyces kasugaensis and S. rimofaciens BOX 1 | Importance of P in live and role of bacteria to its availability Phosphorus is considered as the second most vital plant nutrient as well as second most deficient after nitrogen (Leghari et al, 2016).…”