Production of single-cell proteins from organic matter and residual nitrogen

Photosynthesis in eukaryotes first arose through phagocytotic processes wherein an engulfed cyanobacterium was not digested, but instead became a permanent organelle. Other photosynthetic lineages then arose when eukaryotic cells engulfed other already photosynthetic eukaryotic cells. Some of the resulting lineages subsequently lost their ability for phagocytosis, while many others maintained the ability to do both processes. These mixotrophic taxa have more complicated ecological roles, in that they are both primary producers and consumers that can shift more towards producing the organic matter that forms the base of aquatic food chains, or towards respiring and releasing CO 2 . We still have much to learn about which taxa are predatory mixotrophs as well as about the physiological consequences of this lifestyle, in part, because much of the diversity of unicellular eukaryotes in aquatic ecosystems remains uncultured. Here, we discuss existing methods for studying predatory mixotrophs, their individual biases, and how single-cell approaches can enhance knowledge of these important taxa. The question remains what the gold standard should be for assigning a mixotrophic status to ill-characterized or uncultured taxa—a status that dictates how organisms are incorporated into carbon cycle models and how their ecosystem roles may shift in future lakes and oceans. This article is part of a discussion meeting issue ‘Single cell ecology’.

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Changes occurring in the organic matter during the decomposition of compost heaps

The Journal of Agricultural Science ◽

10.1017/s0021859600010297 ◽

1942 ◽

Vol 32 (4) ◽

pp. 360-372 ◽

Cited By ~ 7

Author(s):

M. R. F. Ashworth

Keyword(s):

Organic Matter ◽

Large Scale ◽

Nutrient Content ◽

Proximate Analysis ◽

Water Soluble ◽

Soluble Nitrogen ◽

Bulk Materials ◽

Residual Nitrogen ◽

Relative Water ◽

Oat Straw

1. The decomposition of the organic matter of four medium to large-scale composts has been studied by analysis of samples taken at intervals.2. The bulk materials of the composts were grass-cuttings, oat-straw, Sphagnum peat and an Eriophorum and Sphagnum peat. All were made up to the same nutrient-content and relative water content.3. The analytical method used was a modification of the scheme of proximate analysis used by Waksman and by Shewan. It was supplemented by ammonia and nitrate determinations, using Olsen's method.4. Observations.A. All composts.(i) An increase in ammonia, water-soluble nitrogen and water-soluble organic matter took place during the first month.(ii) Only low nitrate concentrations were developed.(iii) Very closely parallel changes in H2SO4-soluble nitrogen and residual nitrogen were recorded.(iv) Other nitrogen changes can be described as slight and on the whole as mutually compensating fluctuations.

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Heterotrophy in the earliest gut: a single-cell view of heterotrophic carbon and nitrogen assimilation in sponge-microbe symbioses

The ISME Journal ◽

10.1038/s41396-020-0706-3 ◽

2020 ◽

Vol 14 (10) ◽

pp. 2554-2567 ◽

Cited By ~ 2

Author(s):

Laura Rix ◽

Marta Ribes ◽

Rafel Coma ◽

Martin T. Jahn ◽

Jasper M. de Goeij ◽

...

Keyword(s):

Organic Matter ◽

Single Cell ◽

Secondary Ion Mass Spectrometry ◽

Stable Isotope Probing ◽

Host Cells ◽

Microbial Abundance ◽

Conventional View ◽

Common Notion ◽

Evolutionary Success ◽

Microbial Symbionts

Abstract Sponges are the oldest known extant animal-microbe symbiosis. These ubiquitous benthic animals play an important role in marine ecosystems in the cycling of dissolved organic matter (DOM), the largest source of organic matter on Earth. The conventional view on DOM cycling through microbial processing has been challenged by the interaction between this efficient filter-feeding host and its diverse and abundant microbiome. Here we quantify, for the first time, the role of host cells and microbial symbionts in sponge heterotrophy. We combined stable isotope probing and nanoscale secondary ion mass spectrometry to compare the processing of different sources of DOM (glucose, amino acids, algal-produced) and particulate organic matter (POM) by a high-microbial abundance (HMA) and low-microbial abundance (LMA) sponge with single-cell resolution. Contrary to common notion, we found that both microbial symbionts and host choanocyte (i.e. filter) cells and were active in DOM uptake. Although all DOM sources were assimilated by both sponges, higher microbial biomass in the HMA sponge corresponded to an increased capacity to process a greater variety of dissolved compounds. Nevertheless, in situ feeding data demonstrated that DOM was the primary carbon source for both the LMA and HMA sponge, accounting for ~90% of their heterotrophic diets. Microbes accounted for the majority (65–87%) of DOM assimilated by the HMA sponge (and ~60% of its total heterotrophic diet) but <5% in the LMA sponge. We propose that the evolutionary success of sponges is due to their different strategies to exploit the vast reservoir of DOM in the ocean.

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The degradation of different protein supplements in the rumen of steers and the effects of these supplements on carbohydrate digestion

British Journal Of Nutrition ◽

10.1079/bjn19880136 ◽

1988 ◽

Vol 60 (3) ◽

pp. 669-682 ◽

Cited By ~ 19

Author(s):

A. B. McAllan ◽

J. E. Cockburn ◽

A. P. Williams ◽

R. H. Smith

Keyword(s):

Organic Matter ◽

Single Cell ◽

Rapeseed Meal ◽

Single Cell Protein ◽

Protein Supplementation ◽

Diaminopimelic Acid ◽

Cell Protein ◽

Neutral Sugar ◽

Protein Supplements ◽

Digestible Organic Matter

1. Four steers with simple rumen and abomasal cannulas were given diets consisting of ground and pelleted alkali-treated straw, rolled barley and tapioca supplemented with urea (diet U) or containing single-cell protein (diet SCP), maize-gluten meal (diet MGM) or rapeseed meal (diet RSM) in place of some of the tapioca. The isoenergetic diets were given in a 4 x 4 Latin square design in eight feeds/d at 3-h intervals and provided sufficient metabolizable energy to support a growth rate of approximately 0.5 kg/d. Chromic oxide and polyethylene glycol were given as markers and appropriate samples taken from the rumen and abomasum. Flows (g/d) at the abomasum of organic matter and nitrogenous and carbohydrate constituents were calculated.2. Rumen ammonia levels were similar with all three protein supplements at about 9 mmol/l, which was significantly lower (P < 0.05) than that in animals on diet U (16 mmol/l). Rumen liquid outflow rates (/h) were 0.099, 0.139, 0.125 and 0.160 for diets U, SCP, MGM and RSM respectively; the difference between diet U and diet RSM was significant (P < 0.05). Corresponding values for Cr2O3 outflow rates were 0.027, 0.032, 0.027 and 0.030/h respectively, which did not differ significantly from each other.3. RNA, 35S and diaminopimelic acid (DAP) were used as microbial markers. Efficiencies of microbial-N (MN) synthesis, expressed as g MN/kg apparently digestible organic matter, truly digestible organic matter or carbohydrate fermented, were generally not significantly affected by the diet and averaged 29, 22 and 29 respectively based on mean RNA and 35S markers. Corresponding values derived from DAP of 22, 16 and 21 g MN/kg respectively were all significantly (P < 0.001) lower. Using 35S as microbial marker, MN flows at the abomasum as a proportion of non-ammonia-nitrogen flow were 0.78, 0.64, 0.51 and 0.78 for diets U, SCP, MGM and RSM respectively. Derived true rumen degradability values (g/g intake) of the total dietary N were 0.91, 0.79, 0.69 and 0.90 for diets U, SCP, MGM and RSM respectively. Protein supplement degradabilities for single-cell protein, maize-gluten meal and rapeseed meal were 0.73, 0.51 and 0.98 respectively.4. Mouth-to-abomasum digestibility coefficients of the main neutral-sugar components of dietary poly-saccharides were 0.68, 0.63 and 0.61 for arabinose, xylose and cellulose-glucose on diet U. These values were generally significantly increased with protein supplementation, but to different extents depending on the source. Maximum digestibility values of 0.81, 0.79 and 0.76 were obtained for arabinose, xylose and cellulose-glucose with diet RSM. Starch-glucose digestibility was high (0.90) on all diets and unaffected by supplementation.

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Marine Sponges asChloroflexiHot Spots: Genomic Insights and High-Resolution Visualization of an Abundant and Diverse Symbiotic Clade

mSystems ◽

10.1128/msystems.00150-18 ◽

2018 ◽

Vol 3 (6) ◽

Cited By ~ 18

Author(s):

Kristina Bayer ◽

Martin T. Jahn ◽

Beate M. Slaby ◽

Lucas Moitinho-Silva ◽

Ute Hentschel

Keyword(s):

Organic Matter ◽

Amino Acid ◽

Dissolved Organic Matter ◽

Single Cell ◽

Light And Electron Microscopy ◽

Marine Sponges ◽

Functional Gene ◽

Gene Repertoire ◽

Carbohydrate Degradation ◽

Sponge Symbionts

ABSTRACTMembers of the widespread bacterial phylumChloroflexican dominate high-microbial-abundance (HMA) sponge microbiomes. In the Sponge Microbiome Project,Chloroflexisequences amounted to 20 to 30% of the total microbiome of certain HMA sponge genera with the classes/clades SAR202,Caldilineae, andAnaerolineaebeing the most prominent. We performed metagenomic and single-cell genomic analyses to elucidate the functional gene repertoire ofChloroflexisymbionts ofAplysina aerophoba. Eighteen draft genomes were reconstructed and placed into phylogenetic context of which six were investigated in detail. Common genomic features ofChloroflexisponge symbionts were related to central energy and carbon converting pathways, amino acid and fatty acid metabolism, and respiration. Clade-specific metabolic features included a massively expanded genomic repertoire for carbohydrate degradation inAnaerolineaeandCaldilineaegenomes, but only amino acid utilization by SAR202. WhileAnaerolineaeandCaldilineaeimport cofactors and vitamins, SAR202 genomes harbor genes encoding components involved in cofactor biosynthesis. A number of features relevant to symbiosis were further identified, including CRISPR-Cas systems, eukaryote-like repeat proteins, and secondary metabolite gene clusters.Chloroflexisymbionts were visualized in the sponge extracellular matrix at ultrastructural resolution by the fluorescencein situhybridization-correlative light and electron microscopy (FISH-CLEM) method. Carbohydrate degradation potential was reported previously for “CandidatusPoribacteria” and SAUL, typical symbionts of HMA sponges, and we propose here that HMA sponge symbionts collectively engage in degradation of dissolved organic matter, both labile and recalcitrant. Thus, sponge microbes may not only provide nutrients to the sponge host, but they may also contribute to dissolved organic matter (DOM) recycling and primary productivity in reef ecosystems via a pathway termed the sponge loop.IMPORTANCEChloroflexirepresent a widespread, yet enigmatic bacterial phylum with few cultivated members. We used metagenomic and single-cell genomic approaches to characterize the functional gene repertoire ofChloroflexisymbionts in marine sponges. The results of this study suggest clade-specific metabolic specialization and thatChloroflexisymbionts have the genomic potential for dissolved organic matter (DOM) degradation from seawater. Considering the abundance and dominance of sponges in many benthic environments, we predict that the role of sponge symbionts in biogeochemical cycles is larger than previously thought.

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Electron microscopy of keratinocytes cultured on a collagen substrate used as an allograft for the treatment of chronic wounds

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100130158 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1104-1105

Author(s):

Debby A. Jennings ◽

Michael J. Morykwas ◽

Louis C. Argenta

Keyword(s):

Electron Microscopy ◽

Cell Suspension ◽

Single Cell ◽

Chronic Wounds ◽

Mechanical Stability ◽

Uv Light ◽

Type I ◽

Single Cell Suspension ◽

Collagen Substrate ◽

Dermal Collagen

Grafts of cultured allogenic or autogenic keratlnocytes have proven to be an effective treatment of chronic wounds and burns. This study utilized a collagen substrate for keratinocyte and fibroblast attachment. The substrate provided mechanical stability and augmented graft manipulation onto the wound bed. Graft integrity was confirmed by light and transmission electron microscopy.Bovine Type I dermal collagen sheets (100 μm thick) were crosslinked with 254 nm UV light (13.5 Joules/cm2) to improve mechanical properties and reduce degradation. A single cell suspension of third passage neonatal foreskin fibroblasts were plated onto the collagen. Five days later, a single cell suspension of first passage neonatal foreskin keratinocytes were plated on the opposite side of the collagen. The grafts were cultured for one month.The grafts were fixed in phosphate buffered 4% formaldehyde/1% glutaraldehyde for 24 hours. Graft pieces were then washed in 0.13 M phosphate buffer, post-fixed in 1% osmium tetroxide, dehydrated, and embedded in Polybed 812.

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