Exploring bioactive pigments from marine bacterial isolate from the Indonesian seas

Marine microbes offer a significant source for biodiscovery due to their rich biodiversity and genetic capacity. Particularly, microbial pigments of marine origin are getting more attention in current research due to their widely perceived application as natural food colorants, antioxidant, antimicrobial, and many more. In the past five years, our research group has successfully characterised various bioactive pigments isolated from marine bacteria, including Erythrobacter flavus strain KJ5 that produces unique sulphur-containing carotenoids, Pseudoalteromonas rubra strain PS1 and SB14 that contain antimicrobial prodiginine, and Seonamhaeicola algicola strain CCI for high content of zeaxanthin. This paper describes the challenges we encountered in conducting research in exploring bioactive pigments especially with focus on carotenoid research, reviewed critically on strategy we developed for isolation of isolate as well as identification and elucidation of the pigments, and consideration for future research.

Identification and Verification of the Prodigiosin Biosynthetic Gene Cluster (BGC) in Pseudoalteromonas rubra S4059

Pigmented Pseudoalteromonas strains are renowned for their production of secondary metabolites, and genome mining has revealed a high number of biosynthetic gene clusters (BGCs) for which the chemistry is unknown. Identification of those BGCs is a prerequisite for linking products to gene clusters and for further exploitation through heterologous expression.

Optimising the DPPH Assay for Cell-Free Marine Microorganism Supernatants

Antioxidants prevent ageing and are usually quantified and screened using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. However, this assay cannot be used for salt-containing samples, such as the cell-free supernatants of marine microorganisms that are aggregated under these conditions. Herein, the DPPH solvent (methanol or ethanol) and its water content were optimized to enable the analysis of salt-containing samples, aggregation was observed for alcohol contents of >70%. The water content of methanol influenced the activities of standard antioxidants but did not significantly affect that of the samples. Based on solution stability considerations, 70% aqueous methanol was chosen as the optimal DPPH solvent. The developed method was successfully applied to the cell-free supernatants of marine bacteria (Pseudoalteromonas rubra and Pseudoalteromonas xiamenensis), revealing their high antioxidant activities. Furthermore, it was concluded that this method would be useful for the screening of marine microorganism–derived antioxidants, which also has numerous potential applications, such as salt-fermented foods.

Chitin Degradation Machinery and Secondary Metabolite Profiles in the Marine Bacterium Pseudoalteromonas rubra S4059

Genome mining of pigmented Pseudoalteromonas has revealed a large potential for the production of bioactive compounds and hydrolytic enzymes. The purpose of the present study was to explore this bioactivity potential in a potent antibiotic and enzyme producer, Pseudoalteromonas rubra strain S4059. Proteomic analyses (data are available via ProteomeXchange with identifier PXD023249) indicated that a highly efficient chitin degradation machinery was present in the red-pigmented P. rubra S4059 when grown on chitin. Four GH18 chitinases and two GH20 hexosaminidases were significantly upregulated under these conditions. GH19 chitinases, which are not common in bacteria, are consistently found in pigmented Pseudoalteromonas, and in S4059, GH19 was only detected when the bacterium was grown on chitin. To explore the possible role of GH19 in pigmented Pseudoalteromonas, we developed a protocol for genetic manipulation of S4059 and deleted the GH19 chitinase, and compared phenotypes of the mutant and wild type. However, none of the chitin degrading ability, secondary metabolite profile, or biofilm-forming capacity was affected by GH19 deletion. In conclusion, we developed a genetic manipulation protocol that can be used to unravel the bioactive potential of pigmented pseudoalteromonads. An efficient chitinolytic enzyme cocktail was identified in S4059, suggesting that this strain could be a candidate with industrial potential.

¿Qué hay ahí? Similitudes y diferencias de la microbiota del alga roja Chondracanthus chamissoi de Ancón y Paracas

La gran actividad metabólica que caracteriza la microbiota permite mantener una relación de simbiosis con el ser humano, impactando de forma positiva en el desarrollo vital de ambos. Algunos alimentos aportan a la microbiota, entre estos se encuentran los fermentados, verduras, frutas y algas. La biota de diferentes algas ha sido tipificada, sin embargo no se habían realizado estudios del alga roja más consumida en Perú, Chondracanthus chamissoi (Yuyo). En este estudio se tipificó la microbiota de C. chamissoi Ancón y Paracas, las cuales fueron extraídas del mar, compradas del mercado del lugar, además se muestreó agua de mar de Ancón (Lima) y Paracas (Ica) mediante secuenciación de nueva generación (NGS, por sus siglas en inglés) del gen 16S rRNA. Como resultado se obtuvo un total de 153 323 secuencias, las cuales fueron asignadas taxonómicamente en 19 filos, 41 clases, 90 órdenes, 193 familias, 484 géneros y 716 especies mediante la plataforma Base Space de Illumina. El filo más encontrado fue Proteobacterias seguido por Bacteroidetes y Cyanobacterias. Se encontraron 24 especies en común entre las muestras de alga. Además, se encontró un número elevado de especies presentes solo en muestras extraídas de los mercados correspondientes, indicando posible contaminación cruzada. Entre el 55,27%-58,87% de especies bacterianas encontradas resultaron no estar clasificadas. El análisis semi-cuantitativo permitió a su vez asignar la representación relativa de cada bacteria en las algas de Ancón y Paracas. Muchas especies que se encontraron en una abundancia significativa han sido previamente estudiadas, muchas de ellas implicadas en la industria alimentaria y/o salud de humanos y animales. Este es el caso de Psycrobacter namhaensis; empleada como probiótico para la tilapia del Nilo de manera exitosa. Lewinella marina es capaz de utilizar la celulosa como fuente de energía y así degradarla pudiendo ser útil en la industria cervecera. Pseudoalteromonas rubra posee poder probiótico al mejorar el cultivo de las larvas del pez dorado Seriola lalandi y además Loktanella sp. posee ácidos grasos omega 6, 7, 10. En conjunto, el presente estudio describe de manera exhaustiva la riqueza microbiana asociada al yuyo, importante componente de la gastronomía peruana.

Bioactivity of compounds secreted by symbiont bacteria of Nudibranchs from Indonesia

The aims of this work are to isolate bacterial symbionts from nudibranchs and subsequently to determine anti-Methicillin resistant Staphylococcus aureus (MRSA), cytotoxicity and anti-Herpes simplex virus type 1 (HSV-1) activities of bio compounds. A total of 15 species of nudibranchs were collected from Karimunjawa and five species from Bali, respectively. A total of 245 bacteria isolates were obtained. The anti-MRSA activity screening activity indicated two active bacteria. Ethyl acetate extracts from supernatants, indicating extracelullar compounds, showed an inhibition zone against MRSA at concentrations of 500–1,000 µg/ml. DNA sequence analysis showed that the strain KJB-07 from Phyllidia coelestis was closely related to Pseudoalteromonas rubra, whereas the strain NP31-01 isolated from Phyllidia varicosa was closely related to Virgibacillus salarius. The extract of Pseudoalteromonas rubra was cytotoxic to Vero cells at a concentration of 75 µg/ml. The extract of V. salarius presented no cytotoxicity at concentrations of 5–1,000 µg/ml. No anti HSV-1 was observed for both isolated bacteria. This is the first study describing research on anti-MRSA, cytotoxicity and anti HSV-1 activity of bacterial symbionts from the viscera of nudibranch. Compounds produced by Pseudoalteromonas rubra and V. salarius, had potential anti-MRSA activity. However, only extracts from Pseudoalteromonas rubra showed cytotoxic effects on Vero cells. Three compounds were identified by LC/MS after purification from culture supernatant.

Bioactivity of compounds secreted by symbiont bacteria of Nudibranchs from Indonesia

The aim of this work was to isolate bacterial symbionts from nudibranchs and subsequently to determine anti-Methicillin resistant Staphylococcus aureus (MRSA), cytotoxicity and anti-HSV-1 activities of bio-compounds. Fifteen species of nudibranchs were collected from Karimunjawa and five species from Bali, respectively. A total of 245 bacteria isolates were obtained. The anti-MRSA activity screening activity indicated 2 isolates of active bacteria. Ethyl acetate extracts from supernatants, indicating secreted compounds, showed an inhibition zone against MRSA at concentrations of 500-1000µg/ml. DNA sequence analysis showed that the strainKJB-07 from Phyllidia coelestis was closely related to Pseudoalteromonas rubra, the strain NP31-01 from Phyllidia varicosa was closely related to Virgibacillus salarius. The extract of P. rubra was cytotoxic to Vero cells at a concentration of 75 µg/ml. The extract of V. salarius presented no cytotoxicity at concentrations of 5-1000 µg/ml. No anti-HSV-1 was observed. This is the first reported study describing research on anti-MRSA, cytotoxicity and anti-HSV-1 activity of bacterial symbionts from the viscera of nudibranch. Compounds produced and secreted byPseudoalteromonas rubra and Virgibacillus salarius, symbionts of Nudibranch, had potential anti-MRSA activity. Extracts from P. rubra showed cytotoxic effects on Vero cells, whereas extracts from V. salarius did not show cytotoxic effects. Three compounds were identified by LC/MS after purification from culture supernatant.