Fungicide Activity of Culture Extract from Kocuria palustris 19C38A1 against Fusarium oxysporum

Metabolic Profiling, Antiviral Activity and the Microbiome of Some Mauritian Soft Corals

Soft corals, recognized as sessile marine invertebrates, rely mainly on chemical, rather than physical defense, by secreting intricate secondary metabolites with plausible pharmaceutical implication. Their ecological niche encompasses a diverse community of symbiotic microorganisms which potentially contribute to the biosynthesis of these bioactive metabolites. The emergence of new viruses and heightened viral resistance underscores the urgency to explore novel pharmacological reservoirs. Thus, marine organisms, notably soft corals and their symbionts, have drawn substantial attention. In this study, the chemical composition of four Mauritian soft corals: Sinularia polydactya, Cespitularia simplex, Lobophytum patulum, and Lobophytum crassum was investigated using LC-MS techniques. Concurrently, Illumina 16S metagenomic sequencing was used to identify the associated bacterial communities in the named soft corals. The presence of unique biologically important compounds and vast microbial communities found therein was further followed up to assess their antiviral effects against SARS-CoV-2 and HPV pseudovirus infection. Strikingly, among the studied soft corals, L. patulum displayed an expansive repertoire of unique metabolites alongside a heightened bacterial consort. Moreover, L. patulum extracts exerted some promising antiviral activity against SARS-CoV-2 and HPV pseudovirus infection, and our findings suggest that L. patulum may have the potential to serve as a therapeutic agent in the prevention of infectious diseases, thereby warranting further investigation.

Exploration and Biorefinery Antimicrobial Agent through Solid State Fermentation from Indonesia’s Marine Actinomycetes

This study aimed to obtain novel bioactive compounds derived from actinomycetes associated with marine biota from the coast of Indonesia. Actinomycetes have been identified as a potential source of bioactive compounds through enzymatic fermentation. In order to obtain bioactive compounds from the results of the biorefinery process, cultivation was performed by solid state fermentation (SSF) on shrimp shell waste medium. The inhibitory activity against pathogenic microorganisms was measured based on the optical density of samples from Gorontalo and Buleleng, Bali, Indonesia. Six isolates had a clear zone as an indicator of the chitinase activity of chitinase enzymes. The SSF extract, obtained after 14 days of incubation, was assayed for its antimicrobial activity by the 96-well plate microtiter method. Among the six isolates, isolate 19B19A1 had antibacterial and antifungal activity against Staphylococcus aureus and Malassezia globosa, respectively. DNA analysis indicated that the 19B19A1 isolate was Streptomyces tritolerans 19B19A1 and that its extract contained an alkaloid component that played a role in antimicrobial activity. These results indicate that shrimp shells can be used as a nutrient-rich alternative culture medium for actinomycetes. This study is expected to become a source of information related to biorefinery, especially in the exploration of bioactive compounds produced by actinomycetes.

Antifungal Agent Chitooligosaccharides Derived from Solid-State Fermentation of Shrimp Shell Waste by Pseudonocardia antitumoralis 18D36-A1

Shrimp shell waste is a potential source of the biopolymer chitin. Through fermentation, chitin can be converted into its derivative products. This study aimed to isolate and characterize the products of the biodegradation of chitin from shrimp shell waste through a solid-state fermentation process using actinomycetes. Actinomycete isolates were obtained from tunicate marine biota collected from the waters of Buleleng, Bali, using a dilution technique on 1% chitin colloid agar medium. The isolated actinomycetes were cultivated on a shrimp shell waste medium for 7 days, and then the products of the biodegradation of the oligomers were extracted using water. The extracts of the biodegradation products of the shrimp shells were isolated through several chromatographic steps and analyzed using LC–MS–MS, and the bioactivity of the biodegradation products against fungi was tested. The morphological observations and phylogenetic analysis showed that the isolate 18D36-A1 was a rare actinomycete with the proposed name Pseudonocardia antitumoralis 18D36-A1. The results of the analysis using TLC showed that the solid-state fermented water isolate 18D36-A1 produced several oligomeric components. These results indicate that the isolate 18D36-A1 was able to convert chitin into chitooligosaccharides. Further isolation of the extract produced the active fraction D36A1C38, which can inhibit the growth of fungi by 74% at a concentration of 1 mg/mL. This initial information is very important for further studies related to the development of a solid-state fermentation process for obtaining bioactive compounds from shrimp shell waste.