Traditional and new directions in biotechnological applications of yeast species of the genus Rhodotorula

Drożdże z rodzaju Rhodotorula występują powszechnie w środowisku. Do niedawna postrzegane były głównie jako psujące lub zanieczyszczające żywność saprofity. Jednak odkrycie przez naukowców wielu nowych możliwości ich wykorzystania pozwala sądzić, że mogą stać się w przyszłości znaczącą grupą drobnoustrojów przemysłowych. W niniejszym opracowaniu przedstawiono niektóre kierunki zastosowania drożdży z rodzaju Rhodotorula. Karotenoidy, egzopolisacharydy oraz enzymy produkowane przez biomasę komórkową tych drożdży mogą być wykorzystywane w wielu branżach przemysłu. Równie ważnym aspektem, uwzględnianym przy ocenie przydatności drożdży, jest wykorzystanie ich biomasy komórkowej w procesach wiązania jonów metali bądź biodegradacji odpadów.The yeast species of the genus Rhodotorula are ubiquitous in the human environment. Until recently, they have been mainly perceived as saprophytes, which spoil or contaminate food products. However, owing to many new options discovered by scientists of using them, they could be supposed to become a significant group of micro-organisms in the future. In this paper, some directions of using yeast of the genus Rhodotorula are presented. Carotenoids, exopolysaccharides, and enzymes produced by the biomass of Rhodotorula strain can be applied in many industrial fields. While assessing the usefulness of yeast, another more important aspect is considered, namely, the utilization of their cell biomass in the processes of binding metal ions or in biodegradation of waste/refuse

Evaluation of the ability of the intraclellular fat biosynthesis by Rhodotorula gracilis yeast in media containing potato wastewater enriched with glycerol

Celem badań było określenie zdolności wzrostu drożdży Rhodotorula gracilis i biosyntezy przez nie wewnątrzkomórkowego tłuszczu (SCO – Single Cell Oil) podczas 72-godzinnej hodowli wgłębnej w podłożach zawierających ziemniaczaną odpadową wodę sokową wzbogaconą glicerolem w ilościach 5, 10, 15 i 20% obj. Największy plon biomasy komórkowej (28,65 gs.s.·dm⁻³) uzyskano w podłożu zawierającym 5% obj. glicerolu, a najwięcej wewnątrzkomórkowego tłuszczu (25,57 g·100 gs.s.⁻¹) stwierdzono w biomasie drożdży rosnących w podłożach zawierających 20% obj. glicerolu. Ta ilość tłuszczu była 3 i 5 razy większa w porównaniu z eksperymentami prowadzonymi w podłożu kontrolnym YPD (8,87 g·100 gs.s.⁻¹) i doświadczalnym bez gliceryny (4,81 g·100 gs.s.⁻¹). W podłożach wzbogaconych 15 lub 20% obj. dodatkiem glicerolu największa objętościowa produktywność biosyntezy tłuszczu w komórkach stosowanego szczepu drożdży przekraczała 5 g·dm⁻³. Hodowla wgłębna drożdży Rhodotorula gracilis w podłożu stanowiącym odpadową wodę sokową ziemniaczaną wzbogaconą glicerolem w ilości 15–20% obj. prowadzi do biosyntezy tłuszczu wewnątrzkomórkowego.The biosynthesis of intracellular fat by oleaginous yeast strains based on alternative sources of carbon, nitrogen, phosphorus and mineral ingredients can provide the opportunity for the utilization of the industrial wastes. The culture media for SCO production can include glycerol from biodiesel production as a source of carbon as well as potato wastewater as a source of nitrogen. Potato wastewater is a waste of the production of protein feed obtained by proteins thermal-acid coagulation from potato juice. The aim of the study was to determine the ability of Rhodotorula gracilis yeast to the growth and intracellular biosynthesis of fat during 72-hour bath cultivation in experimental media containing potato wastewater enriched with glycerol. Experimental media contained potato wastewater and diverse addition of glycerol in quantities of 5, 10, 15 or 20% vol. Control medium was YPD. Potato wastewater originated from PEPEES SA Food Industry in Łomża (Central East Poland). The biomass yield, intracellular fat content as well as glycerol in cultivation media content were determined during yeast cultivation. Biomass yield was performed by gravimetric method, while glycerol content by the Milchert’s method. The intracellular fat content was determined after extraction according to the Soxhlet method with petroleum ether. The highest yield of the cell biomass (28.65 gs.s.·dm⁻³) was obtained in the experimental medium with wastewater and 5% of glycerol. Culturing of the yeast of Rhodotorula gracilis in medium containing potato wastewater media enriched with 15 or 20% glycerol leads to the biosynthesis of intracellular fat. The intracellular biosynthesis of fat in the experimental media glycerol occurred in the stationary growth phase. The highest intracellular fat (25.57 g·100 gs.s.⁻¹) was found in yeast biomass from the experimental media containing 20% glycerol. In comparison to the fat content in the biomass from YPD control medium (8.87 g·100 gs.s.⁻¹) and experimental without glycerol (4.81 g·100 gs.s.⁻¹) the value was about 3 and 5 times greater respectively. The volumetric productivity of fat in cells of the yeast strain tested exceeded 5 g·dm⁻³ in potato wastewater media enriched with 15 or 20% glycerol. Increasing the glycerol content in the experimental media (from 5 to 20% vol) led to a reduction in glycerol utilization by yeast (from 86 to 59%). The fact of incomplete utilization of glycerol in experimental media should result in an extension of the submerged culture over 72 hours

Microbial photosynthesis in coral reef sediments (Heron Reef, Australia)

We investigated microphytobenthic photosynthesis at four stations in the coral reef sediments at Heron Reef, Australia. The microphytobenthos was dominated by diatoms, dinoflagellates and cyanobacteria, as indicated by biomarker pigment analysis. Conspicuous algae firmly attached to the sand grains (ca. 100 mm in diameter, surrounded by a hard transparent wall) were rich in peridinin, a marker pigment for dinoflagellates, but also showed a high diversity based on cyanobacterial 16S rDNA gene sequence analysis. Specimens of these algae that were buried below the photic zone exhibited an unexpected stimulation of respiration by light, resulting in an increase of local oxygen concentrations upon darkening. Net photosynthesis of the sediments varied between 1.9 and 8.5 mmol O2 m2 h1 and was strongly correlated with Chl a content, which lay between 31 and 84 mg m2. An estimate based on our spatially limited dataset indicates that the microphytobenthic production for the entire reef is in the order of magnitude of the production estimated for corals. Photosynthesis stimulated calcification at all investigated sites (0.2e1.0 mmol Ca2þ m2 h1). The sediments of at least three stations were net calcifying. Sedimentary N2-fixation rates (measured by acetylene reduction assays at two sites) ranged between 0.9 to 3.9 mmol N2 m2 h1 and were highest in the light, indicating the importance of heterocystous cyanobacteria. In coral fingers no N2-fixation was measurable, which stresses the importance of the sediment compartment for reef nitrogen cycling. 2007 Elsevier Lt

Acquisition of a Novel Sulfur-Oxidizing Symbiont in the Gutless Marine Worm Inanidrilus exumae

Gutless phallodrilines are marine annelid worms without a mouth or gut, which live in an obligate association with multiple bacterial endosymbionts that supply them with nutrition. In this study, we discovered an unusual symbiont community in the gutless phallodriline Inanidrilus exumae that differs markedly from the microbiomes of all 22 of the other host species examined. Comparative 16S rRNA gene sequence analysis and fluorescence in situ hybridization revealed that I. exumae harbors cooccurring gamma-, alpha-, and deltaproteobacterial symbionts, while all other known host species harbor gamma-and either alpha-or deltaproteobacterial symbionts. Surprisingly, the primary chemoautotrophic sulfur oxidizer "Candidatus Thiosymbion" that occurs in all other gutless phallodriline hosts does not appear to be present in I. exumae. Instead, I. exumae harbors a bacterial endosymbiont that resembles "Ca. Thiosymbion" morphologically and metabolically but originates from a novel lineage within the class Gammaproteo-bacteria. This endosymbiont, named Gamma 4 symbiont here, had a 16S rRNA gene sequence that differed by at least 7% from those of other free-living and symbiotic bacteria and by 10% from that of "Ca. Thiosymbion." Sulfur globules in the Gamma 4 symbiont cells, as well as the presence of genes characteristic for autotrophy (cbbL) and sulfur oxidation (aprA), indicate that this symbiont is a chemoautotrophic sulfur oxidizer. Our results suggest that a novel lineage of free-living bacteria was able to establish a stable and specific association with I. exumae and appears to have displaced the "Ca. Thiosymbion" symbionts originally associated with these hosts. IMPORTANCE All 22 gutless marine phallodriline species examined to date live in a highly specific association with endosymbiotic, chemoautotrophic sulfur oxidizers called "Ca. Thiosymbion." These symbionts evolved from a single common ancestor and represent the ancestral trait for this host group. They are transmitted vertically and assumed to be in transition to becoming obligate endosymbionts. It is therefore surprising that despite this ancient, evolutionary relationship between phallodriline hosts and "Ca. Thiosymbion," these symbionts are apparently no longer present in Inanidrilus exumae. They appear to have been displaced by a novel lineage of sulfur-oxidizing bacteria only very distantly related to "Ca. Thiosymbion." Thus, this study highlights the remarkable plasticity of both animals and bacteria in establishing beneficial associations: the phallodriline hosts were able to acquire and maintain symbionts from two very different lineages of bacteria, while sulfur-oxidizing bacteria from two very distantly related lineages were able to independently establish symbiotic relationships with phallodriline hosts

Closely coupled evolutionary history of ecto- and endosymbionts from two distantly related animal phyla

The level of integration between associated partners can range from ectosymbioses to extracellular and intracellular endosymbioses, and this range has been assumed to reflect a continuum from less intimate to evolutionarily highly stable associations. In this study, we examined the specificity and evolutionary history of marine symbioses in a group of closely related sulphur-oxidizing bacteria, called Candidatus Thiosymbion, that have established ecto-and endosymbioses with two distantly related animal phyla, Nematoda and Annelida. Intriguingly, in the ectosymbiotic associations of stilbonematine nematodes, we observed a high degree of congruence between symbiont and host phylogenies, based on their ribosomal RNA (rRNA) genes. In contrast, for the endosymbioses of gutless phallodriline annelids (oligochaetes), we found only a weak congruence between symbiont and host phylogenies, based on analyses of symbiont 16S rRNA genes and six host genetic markers. The much higher degree of congruence between nematodes and their ectosymbionts compared to those of annelids and their endosymbionts was confirmed by cophylogenetic analyses. These revealed 15 significant codivergence events between stilbonematine nematodes and their ectosymbionts, but only one event between gutless phallodrilines and their endosymbionts. Phylogenetic analyses of 16S rRNA gene sequences from 50 Cand. Thiosymbion species revealed seven well-supported clades that contained both stilbonematine ectosymbionts and phallodriline endosymbionts. This closely coupled evolutionary history of marine ecto-and endosymbionts suggests that switches between symbiotic lifestyles and between the two host phyla occurred multiple times during the evolution of the Cand. Thiosymbion clade, and highlights the remarkable flexibility of these symbiotic bacteria