The emergence of large number of antimicrobial-resistant organisms has given alarming magnitude. Nature is historically the source of drugs, and microorganisms have provided a significant number of antibiotic compounds, which are used every day in the treatment of many infectious diseases. However, the introduction to the pharmaceutical market of new therapeutic molecules has largely decreased during the last two decades. In this review, antibiotics from the genus Micromonospora are recognized as potential biofactory for new antibiotic production. The Micromonospora has been deeply studied and more than 100 antibiotics isolated from different Micromonospora strains. In addition, comprehensive information about the recent development in the field of analytical, biological and bioinformatics screening tools, which recently used in the discovery of new therapeutic compounds, are provided. It is widely believed that reviving old antibiotics produced by Micromonospora is possible and the study of this genus is still interesting for novel bioactive molecules discovery.

The infusions of Thymus pallescens Noë, Saccocalyx satureioides Coss. et Dur., Ptychotis verticillata Briq. and Limoniastrum guyonianum Boiss. have been used as medicinal remedies for many diseases in Algerian folk medicine. These species have also been well documented as rich sources of phytochemicals, such as phenolic compounds with wide diversified chemical structures, which exhibit far-ranging biological activities. Thus, the phenolic compound profile of the aqueous extracts, obtained by infusing, of the mentioned species was obtained by HPLC-DAD-ESI/MS, and their antibacterial activity was evaluated against clinical isolates. Several phenolic acids were identified and quantified, particularly caffeic acid derivatives along with glycosylated flavonoids. T. pallescens and S. satureioides contain 13 phenolic compounds, where rosmarinic acid was the most abundant phenolic acid present, while L. guyonianum presented myricetin-3-O-glucoside and myricetin-O-rhamnoside as the main compounds among the eight detected molecules. P. verticillata presented a profile of ten phenolic compounds, where 5-O-caffeoylquinic acid was the most abundant phenolic acid, followed by the flavone luteolin-3-O-glucoside. The antibacterial activity of the infusions ranged between 2.5 and 20 mg mL (MIC values), and L. guyonianum showed the highest activity against all of the tested bacteria, Staphylococcus aureus and Pseudomonas aeruginosa being the most sensitive and resistant strains, respectively. Thus, the studied plant species are sources of natural antibacterial substances that can be used to fight against pathogenic microorganisms.

A Gram-positive strain, ADR1, was isolated from soil collected from the Algerian Sahara Desert. The ethyl acetate extract of the fermentation broth showed cytotoxic activity against the PANC-1 cell line (37.1 ± 1.3% viability when applied at a concentration of 100 µg/mL). Fractionation and NMR analysis of two peaks absorbing at 490 nm revealed that they represented β- and γ-rubromycin, anticancer antibiotic compounds. The ADR1 strain contained LL-diaminopimelic acid in the whole-cell hydrolysate, and the partial 16S ribosomal RNA gene sequence (1392 bp, Accession No. KF947515) showed 99% sequence similarity to Streptomyces species. Therefore, the name Streptomyces sp. ADR1 was proposed and deposited in the Wellness Industries Culture Collection (WICC) of the Institute of Bioproduct Development, UTM, Malaysia, under the number (WICC- B86). In a 16 L stirred-tank bioreactor, the stain was adapted to submerged culture conditions and produced rubromycins at a relatively high concentration, with maximums of 24.58 mg/L and 356 mg/L for β- and γ-rubromycins, respectively.