A novel Penicillium sumatraense isolate reveals an arsenal of degrading enzymes exploitable in algal bio-refinery processes

Abstract

Background Microalgae are coming to the spotlight due to their potential applications in a wide number of fields ranging from the biofuel to the pharmaceutical sector. However, several factors such as low productivity, expensive harvesting procedures and difficult metabolite extractability limit their full utilization at industrial scale. Similarly to the successful employment of enzymatic arsenals from lignocellulolytic fungi to convert lignocellulose into fermentable sugars for bioethanol production, specific algalytic formulations could be used to improve the extractability of lipids from microalgae to produce biodiesel. Currently, the research areas related to algivorous organisms, algal saprophytes and the enzymes responsible for the hydrolysis of algal cell wall are still little explored. Results Here, an algal trap method for capturing actively growing microorganisms was successfully used to isolate a filamentous fungus, that was identified by whole-genome sequencing, assembly and annotation as a novel Penicilliumsumatraense isolate. The fungus, classified as P.sumatraense AQ67100, was able to assimilate heat-killed Chlorellavulgaris cells by an enzymatic arsenal composed of proteases such as dipeptidyl- and amino-peptidases, β-1,3-glucanases and glycosidases including α- and β-glucosidases, β-glucuronidase, α-mannosidases and β-galactosidases. The treatment of C.vulgaris with the filtrate from P.sumatraense AQ67100 increased the release of chlorophylls and lipids from the algal cells by 42.6 and 48.9%, respectively. Conclusions The improved lipid extractability from C.vulgaris biomass treated with the fungal filtrate highlighted the potential of algal saprophytes in the bioprocessing of microalgae, posing the basis for the sustainable transformation of algal metabolites into biofuel-related compounds.

Characterization of two 1,3-β-glucan-modifying enzymes from Penicillium sumatraense reveals new insights into 1,3-β-glucan metabolism of fungal saprotrophs

“…P. pastoris was selected as expression host for the recombinant production of the two putative 1,3-β-glucan modifying enzymes from the fungus P. sumatraense AQ67100 (i.e., G9376 and G7048) (Additional File 1 : Data S1; [ 3 ]). Unfortunately, the recombinant expression of the entire G7048 (aa.…”

“…The gene g9376 was predicted to encode a putative exo-1,3-β-glucanase [ 3 ]. To effectively characterize G9376 in vitro in terms of catalytic activity and substrate specificity, we first tested its ability to hydrolyze different di- and polysaccharides including 1,3-β-linked saccharides.…”

“…These organisms degrade plant biomass by secreting arsenals of CWDEs whose synthesis can be stimulated by culturing fungi on agricultural wastes, thus lowering the production costs associated with fungal fermentation processes [ 4 ]. The opportunistic and saprotrophic nature of fungi is also evidenced in Penicillium sumatraense AQ67100, a filamentous fungus that feeds on plants [ 9 ], macro- [ 10 ] and micro-algae [ 3 ]; noteworthy, the cell wall of land plants and algae is very different both in terms of composition and structure [ 4 ], pointing to P. sumatraense as a highly versatile saprotroph. To assimilate C. vulgaris cells, P. sumatraense AQ67100 secretes an enzymatic arsenal mainly composed of proteases, 1,3-β-glucanases and glycosidases.…”

“…To provide new insight into the glucan metabolism in the Penicillium genus, we focused on two enzymes (named G9376 and G7048) that have been previously identified in the culture filtrate of P. sumatraense AQ67100 fed with C. vulgaris biomass [ 3 ]. Based on prediction software analysis, the selected enzymes G9376 and G7048 correspond to a putative exo-1,3-β-glucanase and a putative glucan endo-1,3-β-glucosidase eglC, respectively.…”

The First Comprehensive Biodiversity Study of Culturable Fungal Communities Inhabiting Cryoconite Holes in the Werenskiold Glacier on Spitsbergen (Svalbard Archipelago, Arctic)

“…In both cases, the fungus was described as a phytopathogen infecting apples or bamboo. Most recently, P. sumatraense was isolated using an algal trap and described as being capable of assimilating Chlorella vulgaris [ 71 ]. Due to a limited number of reports on both fungi, we conclude that we are the first to describe both species ( P. cumulodentata and P. sumatraense ) in polar regions.…”