Antarctic Porifera homogenates as a source of enzymes and antibacterial substances: first results

Abstract

Marine Porifera (sponges) are known to produce several bioactive metabolites having a biotechnological potential, mostly derived from their bacterial symbionts; however, current knowledge on the production of metabolites such as enzymes and antibacterial molecules in sponges living in Antarctic environments is not fully exhaustive and needs further deepened investigation. The interest in discovering the broad spectrum of natural products potentially derived from species adapted to colonize extreme environments stimulates the research toward Antarctic sponge bioprospection. In this study, whole homogenates of Antarctic Demospongiae, belonging to five different species [Haliclona (Rhizoniera) sp., Haliclona (Rhizoniera) dancoi, Microxina sarai, Dendrilla antarctica, and Mycale acerata] were collected from Terra Nova Bay (Ross Sea) and examined for presence and activity of enzymes, including lysozyme, and antibacterial substances. Enzyme activities (leucine aminopeptidase, beta-glucosidase, and alkaline phosphatase) were measured using fluorogenic substrates; lysozyme content was determined on plates containing lyophilized Micrococcus lysodeikticus cell walls as a substrate. Homogenates were screened in microtiter plates for their antibacterial activity against Antarctic bacterial isolates, and the absorbance reduction was measured with a microplate reader. All homogenates exhibited proteolytic, glycolytic, and phosphatasic activities, lysozyme and antibacterial activities at near “in situ” temperature (5 °C), with some differences among the examined species. Results confirmed that Antarctic sponge homogenates are interesting sources of different bioactive substances, likely produced from associated bacterial symbionts, and that could have great potential to be used in medicine or industrial applications.

First report on pollutant accumulation and associated microbial communities in the freshwater sponge Spongilla lacustris (Linnaeus, 1759) from the sub‐Arctic Pasvik River (Norway)

“…Sponge symbionts are known to produce secondary metabolites and enzymes. Crude homogenates of Antarctic sponges were observed to exhibit proteolytic, phosphatasic, and glycolytic activities (Caruso et al, 2022). Variable enzyme concentrations, comparable for magnitude to those measured in S. lacustris , were detected depending on the examined species, with Haliclona sp.…”

“…Variable enzyme concentrations, comparable for magnitude to those measured in S. lacustris , were detected depending on the examined species, with Haliclona sp. showing the highest LAP activities and Dendrilla antarctica Topsent, 1915 the highest GLU and AP activities, having a minimum level of hydrolytic enzymes in Mycale (Oxymycale) acerata Kirkpatrick, 1907 for all three enzymes (Caruso et al, 2022). Conversely to S. lacustris , in another species of Spongillidae, namely, Corvomeyenia carolinensis Harrison, 1971, did not detect AP in a histochemical study.…”

“…The activity rates of the enzymes leucine aminopeptidase (LAP), alkaline phosphatase (AP), and beta‐glucosidase (GLU) as the expression of the proteolytic, phosphatasic, and glycolytic activities were determined using the fluorogenic method reported by Caruso et al (2022). These parameters were chosen to get insights on the sponges' potential ability to breakdown complex organic molecules and get nutrients such as nitrogen and phosphorus, being LAP and AP, respectively, involved in the decomposition of proteins and phosphate esters, as well as to get carbon sources (both LAP and GLU).…”

“…Sponge homogenates in sterile physiological saline (ratio 1:10, w/v) were incubated with fluorogenic reagents derived from methylcoumarine (MCA) and methylumbelliferone (MUF) (5‐mM stock solutions of Leucine‐MCA, 4‐MUF‐beta‐D‐glucopyranoside, MUF‐glu, and MUF‐phosphate, Merck Life Science S.r.l., Milan, Italy) to obtain final concentrations of 10, 30, and 100 nM. The fluorescence increase recorded 2 h after incubation at in situ temperature was measured with a fluorimeter (Jenway model 6280, London, UK), where MCA and MUF were used as the standards, according to an experimental protocol conventionally used at the CNR laboratory (Caruso et al, 2022). As the blank, physiological saline without the addition of the sponge homogenate was measured.…”

Chemical and microbiological insights into two littoral Antarctic demosponge species: Haliclona (Rhizoniera) dancoi (Topsent 1901) and Haliclona (Rhizoniera) scotti (Kirkpatrick 1907)

“…Haliclonidae; De Weerdt, 2002) are quite common in the marine environments, even in Antarctica (Barthel and Gutt, 1992). They have been proven to be a prolific source of secondary metabolites (mainly alkaloids) with several bioactivities, including antifungal, antibacterial, antiviral, anti-inflammatory, antimalarial, cytotoxic, and hemolytic activities (Avila et al, 2022;Caruso et al, 2022b). In particular, within Chalinidae, Antarctic Haliclona spp.…”