Cellular basis of tissue regeneration by omentum

The omentum is a sheet-like tissue attached to the greater curvature of the stomach and contains secondary lymphoid organs called milky spots. The omentum has been used for its healing potential for over 100 years by transposing the omental pedicle to injured organs (omental transposition), but the mechanism by which omentum helps the healing process of damaged tissues is not well understood. Omental transposition promotes expansion of pancreatic islets, hepatocytes, embryonic kidney, and neurons. Omental cells (OCs) can be activated by foreign bodies in vivo. Once activated, they become a rich source for growth factors and express pluripotent stem cell markers. Moreover, OCs become engrafted in injured tissues suggesting that they might function as stem cells.Omentum consists of a variety of phenotypically and functionally distinctive cells. To understand the mechanism of tissue repair support by the omentum in more detail, we analyzed the cell subsets derived from the omentum on immune and inflammatory responses. Our data demonstrate that the omentum contains at least two groups of cells that support tissue repair, immunomodulatory myeloid derived suppressor cells and omnipotent stem cells that are indistinguishable from mesenchymal stem cells. Based on these data, we propose that the omentum is a designated organ for tissue repair and healing in response to foreign invasion and tissue damage.     

Surface antigenic profiling of stem cells from human omentum fat in comparison with subcutaneous fat and bone marrow

Omentum fat derived stem cells have emerged as an alternative and accessible therapeutic tool in recent years in contrast to the existing persuasive sources of stem cells, bone marrow and subcutaneous adipose tissue. However, there has been a scanty citation on human omentum fat derived stem cells. Furthermore, identification of specific cell surface markers among aforesaid sources is still controversial. In lieu of this existing perplexity, the current research work aims at signifying omentum fat as a ground-breaking source of stem cells by surface antigenic profiling of stem cell population. In this study, we examined and compared the profiling of cell surface antigenic expressions of hematopoietic stem cells, mesenchymal stem cells, cell adhesion molecules and other unique markers such as ABCG2, ALDH and CD 117 in whole cell population of human omentum fat, subcutaneous fat and bone marrow. The phenotypic characterization through flowcytometry revealed the positive expressions of CD 34, CD 45, CD 133, HLADR, CD 90, CD 105, CD 73, CD 29, CD 13, CD 44, CD 54, CD 31, ALDH and CD 117 in all sources. The similarities between the phenotypic expressions of omentum fat derived stem cells to that of subcutaneous fat and bone marrow substantiates that identification of ultimate source for curative therapeutics is arduous to assess. Nevertheless, these results support the potential therapeutic application of omentum fat derived stem cells.

Electronic supplementary material

The online version of this article (doi:10.1007/s10616-012-9427-4) contains supplementary material, which is available to authorized users.     

Unusual polyamines in slime molds Physarum polycephalum and Dictyostelium discoideum

We analyzed the cellular contents of not only major polyamines but also minor polyamines in slime molds Physarum polycephalum and Dictyostelium discoideum. The presence of putrescine and spermidine in either plasmodia or myxamoebae of these molds as major polyamines was confirmed. In addition to these polyamines, appreciable amounts of 1,3-diaminopropane were detected in P. polycephalum and D. discoideum. Cadaverine and sym-homospermidine were detected in P. polycephalum even when the slime mold was cultured in a chemically defined growth medium. Spermine was not detected when these molds were grown in synthetic media. Other "unusual" polyamines such as norspermidine, norspermine, thermospermine, aminopropylcadaverine, and canavalmine were not detected in either mold.     

Haemopoietic progenitors in the adult mouse omentum: permanent production of B lymphocytes and monocytes

The coelome-associated lympho-myeloid tissues, including the omentum, are derived from early embryo haemopoietic tissue of the splanchnopleura, and produce B lymphocytes and macrophages. They are reactive in pathologies involving coelomic cavities, in which they can expand in situ the cells of inflammatory infiltrates. We have addressed the question of the role of the adult omentum in permanent basal production of early lymphopoietic progenitors (pro-B/pre-B cells), through characterisation of omentum cells ex vivo, and study of their in vitro differentiation. We have shown that the murine omentum produces early haemopoietic progenitors throughout life, including B-cell progenitors prior to the Ig gene recombination expressing RAG-1 and 5, as well as macrophages. Their production is stroma-dependent. The omentum stroma can supply in vitro the cytokines (SDF-1, Flt3 ligand and IL-7) and the molecular environment required for generation of these two cell lineages. Omentum haemopoietic progenitors are similar to those observed in foetal blood cell production, rather than to progenitors found in the adult haemopoietic tissue in the bone marrow—in terms of phenotype expression and differentiation capacity. We conclude that a primitive pattern of haemopoiesis observed in the early embryo is permanently preserved and functional in the adult omentum, providing production of cells engaged in nonspecific protection of abdominal intestinal tissue and of the coelomic cavity.Supported by CNPq, FINEP and PADCT grants of the Brazilian Ministry of Science and Technology, and a FAPERJ grant of the Rio de Janeiro State Government     

Printing Thermoresponsive Reverse Molds for the Creation of Patterned Two-component Hydrogels for 3D Cell Culture

Bioprinting is an emerging technology that has its origins in the rapid prototyping industry. The different printing processes can be divided into contact bioprinting^1-4 (extrusion, dip pen and soft lithography), contactless bioprinting^5-7 (laser forward transfer, ink-jet deposition) and laser based techniques such as two photon photopolymerization⁸. It can be used for many applications such as tissue engineering^9-13, biosensor microfabrication^14-16 and as a tool to answer basic biological questions such as influences of co-culturing of different cell types¹⁷. Unlike common photolithographic or soft-lithographic methods, extrusion bioprinting has the advantage that it does not require a separate mask or stamp. Using CAD software, the design of the structure can quickly be changed and adjusted according to the requirements of the operator. This makes bioprinting more flexible than lithography-based approaches.Here we demonstrate the printing of a sacrificial mold to create a multi-material 3D structure using an array of pillars within a hydrogel as an example. These pillars could represent hollow structures for a vascular network or the tubes within a nerve guide conduit. The material chosen for the sacrificial mold was poloxamer 407, a thermoresponsive polymer with excellent printing properties which is liquid at 4 °C and a solid above its gelation temperature ~20 °C for 24.5% w/v solutions¹⁸. This property allows the poloxamer-based sacrificial mold to be eluted on demand and has advantages over the slow dissolution of a solid material especially for narrow geometries. Poloxamer was printed on microscope glass slides to create the sacrificial mold. Agarose was pipetted into the mold and cooled until gelation. After elution of the poloxamer in ice cold water, the voids in the agarose mold were filled with alginate methacrylate spiked with FITC labeled fibrinogen. The filled voids were then cross-linked with UV and the construct was imaged with an epi-fluorescence microscope.     

Reconstructing the breast mound employing a secondary island omental skin flap

We have shown in an initial animal study that omentum will adequately vascularize a skin flap and allow transfer of this tissue composite for use in surgical reconstruction of the breast. Based on this experimental procedure, a technique employing a two-stage operation has been developed and used in 21 female patients in reconstruction of the breast after radical mastectomy. In the first stage, the omentum, attached to one gastroepiploic artery and vein, is exteriorized to the subcutaneous tissue of the lower abdominal wall. In the second stage, the distal omentum, now vascularizing the overlying skin and soft tissue, is moved as a secondary island flap to the anterior chest wall to complete the breast reconstruction. In all but 1 of our 21 patients who have been followed for 1 to 8 years, reconstruction of large defects, including the chest wall, breast mound, and infraclavicular axillary fold depression, was performed without use of a prosthesis. In one patient, there was complete necrosis of the flap due to vascular impairment; there were three instances of delayed healing and a significant but partial loss of the flap in one patient. All complications were encountered in the first 10 patients of the series during the time the technique was being refined.     

Experimental model for studying the mechanical effects of +Gz accelerations on the brain

Bovine brains were excised and placed into a transparent mold equipped with a pump and perfusion system. This unit was then centrifuged and changes in brain contour were video recorded. Analysis of the resulting images showed that changes occurred in brain structures as a result of crushing. The effects of perfusion on the amount of deformation and other results are discussed.     

Three-dimensional Biomimetic Technology: Novel Biorubber Creates Defined Micro- and Macro-scale Architectures in Collagen Hydrogels

Tissue scaffolds play a crucial role in the tissue regeneration process. The ideal scaffold must fulfill several requirements such as having proper composition, targeted modulus, and well-defined architectural features. Biomaterials that recapitulate the intrinsic architecture of in vivo tissue are vital for studying diseases as well as to facilitate the regeneration of lost and malformed soft tissue. A novel biofabrication technique was developed which combines state of the art imaging, three-dimensional (3D) printing, and selective enzymatic activity to create a new generation of biomaterials for research and clinical application. The developed material, Bovine Serum Albumin rubber, is reaction injected into a mold that upholds specific geometrical features. This sacrificial material allows the adequate transfer of architectural features to a natural scaffold material. The prototype consists of a 3D collagen scaffold with 4 and 3 mm channels that represent a branched architecture. This paper emphasizes the use of this biofabrication technique for the generation of natural constructs. This protocol utilizes a computer-aided software (CAD) to manufacture a solid mold which will be reaction injected with BSA rubber followed by the enzymatic digestion of the rubber, leaving its architectural features within the scaffold material.     

3D Printer Generated Tissue iMolds for Cleared Tissue Using Single- and Multi-Photon Microscopy for Deep Tissue Evaluation

Background

Pathological analyses and methodology has recently undergone a dramatic revolution. With the creation of tissue clearing methods such as CLARITY and CUBIC, groups can now achieve complete transparency in tissue samples in nano-porous hydrogels. Cleared tissue is then imagined in a semi-aqueous medium that matches the refractive index of the objective being used. However, one major challenge is the ability to control tissue movement during imaging and to relocate precise locations post sequential clearing and re-staining.

Methods

Using 3D printers, we designed tissue molds that fit precisely around the specimen being imaged. First, images are taken of the specimen, followed by importing and design of a structural mold, then printed with affordable plastics by a 3D printer.

Results

With our novel design, we have innovated tissue molds called innovative molds (iMolds) that can be generated in any laboratory and are customized for any organ, tissue, or bone matter being imaged. Furthermore, the inexpensive and reusable tissue molds are made compatible for any microscope such as single and multi-photon confocal with varying stage dimensions. Excitingly, iMolds can also be generated to hold multiple organs in one mold, making reconstruction and imaging much easier.

Conclusions

Taken together, with iMolds it is now possible to image cleared tissue in clearing medium while limiting movement and being able to relocate precise anatomical and cellular locations on sequential imaging events in any basic laboratory. This system provides great potential for screening widespread effects of therapeutics and disease across entire organ systems.

     

Epithelial machines of morphogenesis and their potential application in organ assembly and tissue engineering

Sheets of embryonic epithelial cells coordinate their efforts to create diverse tissue structures such as pits, grooves, tubes, and capsules that lead to organ formation. Such cells can use a number of cell behaviors including contractility, proliferation, and directed movement to create these structures. By contrast, tissue engineers and researchers in regenerative medicine seeking to produce organs for repair or replacement therapy can combine cells with synthetic polymeric scaffolds. Tissue engineers try to achieve these goals by shaping scaffold geometry in such a way that cells embedded within these scaffold self-assemble to form a tissue, for instance aligning to synthetic fibers, and assembling native extracellular matrix to form the desired tissue-like structure. Although self-assembly is a dominant process that guides tissue assembly both within the embryo and within artificial tissue constructs, we know little about these critical processes. Here, we compare and contrast strategies of tissue assembly used by embryos to those used by engineers during epithelial morphogenesis and highlight opportunities for future applications of developmental biology in the field of tissue engineering.     

Immobilization of trypsin onto "molded" macroporous poly(glycidyl methacrylate-co-ethylene dimethacrylate) rods and use of the conjugates as bioreactors and for affinity chromatography

Trypsin immobilization onto continuous "molded" rods of porous poly(glycidyl methacrylate-co-ethylene dimethacrylate) and some applications of the conjugate have been studied. The rods polymerized within a tubular mold (chromatographic column), were treated in situ with ethylenediamine, activated with glutaraldehyde and finally modified with trypsin. The performance of the trypsin-modified rods was evaluated and compared to that of poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads, modified with the same enzyme. Overall the enzyme-modified rods performed substantially better than the corresponding beads. In particular, the performance of the molded supports as enzymatic reactors or as chromatographic media benefits greatly from the enhanced mass transfer that is characteristic of the molded rod at high flow rates. (c) 1996 John Wiley & Sons, Inc.     

聚四氟乙烯微针模具的性能考察

目的:考察用聚四氟乙烯(PTFE)制作相转化水凝胶微针模具的性能。方法:聚四氟乙烯模具经过粉末的过筛、压制、烧结、制孔而得。实验制备了不同聚四氟乙烯粉料粒度、不聚四氟乙烯粉料用料量、不同生料板压制压力的聚四氟乙烯微针模具,向模具中浇注以PVA为基质的聚合物溶液,通过冷冻解冻制得相转化水凝胶微针,考察模具的孔径、载料量以及微针的揭膜难易程度和完形率。结果:80目以上细度的模具透光性能均一;随着聚四氟乙烯用料量的增加和生料板压制压力的增大,模具的孔径和载药量减小,揭膜更容易、完形率更高。结论:聚四氟乙烯模具的性能与其密度密切相关,密度越大的模具,蠕变的随意性越大,因而孔洞均一性下降,但是揭膜性能变好,完形率提高。这两个相反的趋势提示我们,四氟乙烯模具的优劣是相转化水凝胶微针中的第一个控制性因素,聚四氟乙烯是制作微针模具的可接受材料,有进一步研究的价值。     

Rapid and Low-cost Prototyping of Medical Devices Using 3D Printed Molds for Liquid Injection Molding

Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using traditional liquid injection molding processes can be an expensive process due to tooling and equipment costs. As a result, it has traditionally been impractical to use liquid injection molding for low-cost, rapid prototyping applications. We have devised a method for rapid and low-cost production of liquid elastomer injection molded devices that utilizes fused deposition modeling 3D printers for mold design and a modified desiccator as an injection system. Low costs and rapid turnaround time in this technique lower the barrier to iteratively designing and prototyping complex elastomer devices. Furthermore, CAD models developed in this process can be later adapted for metal mold tooling design, enabling an easy transition to a traditional injection molding process. We have used this technique to manufacture intravaginal probes involving complex geometries, as well as overmolding over metal parts, using tools commonly available within an academic research laboratory. However, this technique can be easily adapted to create liquid injection molded devices for many other applications.     

A 10-year experience in nasal reconstruction with the three-stage forehead flap

Because of its ideal color and texture, forehead skin is acknowledged as the best donor site with which to resurface the nose. However, all forehead flaps, regardless of their vascular pedicles, are thicker than normal nasal skin. Stiff and flat, they do not easily mold from a two-dimensional to a three-dimensional shape. Traditionally, the forehead is transferred in two stages. At the first stage, frontalis muscle and subcutaneous tissue are excised distally and the partially thinned flap is inset into the recipient site. At a second stage, 3 weeks later, the pedicle is divided. However, such soft-tissue "thinning" is limited, incomplete, and piecemeal. Flap necrosis and contour irregularities are especially common in smokers and in major nasal reconstructions. To overcome these problems, the technique of forehead flap transfer was modified. An extra operation was added between transfer and division.At the first stage, a full-thickness forehead flap is elevated with all its layers and is transposed without thinning except for the columellar inset. Primary cartilage grafts are placed if vascularized intranasal lining is present or restored. Importantly, at the first stage, skin grafts or a folded forehead flap can be used effectively for lining. A full-thickness skin graft will reliably survive when placed on a highly vascular bed. A full-thickness forehead flap can be folded to replace missing cover skin, with a distal extension, in continuity, to supply lining. At the second stage, 3 weeks later during an intermediate operation, the full-thickness forehead flap, now healed to its recipient bed, is physiologically delayed. Forehead skin with 3 to 4 mm of subcutaneous fat (nasal skin thickness) is elevated in the unscarred subcutaneous plane over the entire nasal inset, except for the columella. Skin grafts or folded flaps integrate into adjacent normal lining and can be completely separated from the overlying cover from which they were initially vascularized. If used, a folded forehead flap is incised free along the rim, completely separating the proximal cover flap from the distal lining extension. The underlying subcutaneous tissue, frontalis muscle, and any previously positioned cartilage grafts are now widely exposed, and excess soft tissue can be excised to carve an ideal subunit, rigid subsurface architecture. Previous primary cartilage grafts can be repositioned, sculpted, or augmented, if required. Delayed primary cartilage grafts can be placed to support lining created from a skin graft or a folded flap. The forehead cover skin (thin, supple, and conforming) is then replaced on the underlying rigid, recontoured, three-dimensional recipient bed. The pedicle is not transected. At a third stage, 3 weeks later (6 weeks after the initial transfer), the pedicle is divided.Over 10 years in 90 nasal reconstructions for partial and full-thickness defects, the three-stage forehead flap technique with an intermediate operation was used with primary and delayed primary grafts, and with intranasal lining flaps (n = 15), skin grafts (n = 11), folded forehead flaps (n = 3), turnover flaps (n = 5), prefabricated flaps (n = 4), and free flaps for lining (n = 2). Necrosis of the forehead flap did not occur. Late revisions were not required or were minor in partial defects. In full-thickness defects, a major revision and more than two minor revisions were performed in less than 5 percent of patients. Overall, the aesthetic results approached normal.The planned three-stage forehead flap technique of nasal repair with an intermediate operation (1) transfers subtle, conforming forehead skin of ideal thinness for cover, with little risk of necrosis; (2) uses primary and delayed primary grafts and permits modification of initial cartilage grafts to correct failures of design, malposition, or scar contraction before flap division; (3) creates an ideal, rigid subsurface framework of hard and soft tissue that is reflected through overlying skin and blends well into adjacent recipient tissues; (4) expands the application of lining techniques to include the use of skin grafts for lining at the first stage, or as a "salvage procedure" during the second stage, and also permits the aesthetic use of folded forehead flaps for lining; (5) ensures maximal blood supply and vascular safety to all nasal layers; (6) provides the surgeon with options to salvage reconstructive catastrophes; (7) improves the aesthetic result while decreasing the number and difficulty of revision operations and overall time for repair; and (8) emphasizes the interdependence of anatomy (cover, lining, and support) and provides insight into the nature of wound injury and repair in nasal reconstruction.     

Mold Sensitivity in the Allergic Respiratory Diseases

A study to determine the role of mold allergens in the allergic respiratory diseases was made by reviewing the skin sensitivity reactions to molds of 257 consecutive cases of asthma and/or rhinitis in southwestern British Columbia. Failure to adequately seek out and to treat even minor mold allergy was noted to be a frequent cause of therapeutic failure or of only limited success. Apparently bearing a consistent relation to age and being most prevalent in the mature adult, allergy to fungi appeared to develop slowly and insidiously. The incidence of mold sensitivity was 78.5% and exceeded that of house dust sensitivity by 3.1%. Evidence of clinical sensitivity was present in excess of 52.4% of mold-sensitive patients. Asthmatic patients showed a greater incidence of sensitivity to molds and to multiplicity of species than did patients with rhinitis only. The hypothesized evolution of rhinitis to asthma appeared to be paralleled by the acquisition of sensitivity to increasing numbers of species of fungi. This suggests that the development of sensitivity to multiple mold species may be an etiologic factor in the production of the asthmatic state.     

Immediate breast reconstruction with tissue expansion

Between October of 1983 and June of 1985, 31 patients underwent primary breast reconstruction with tissue expansion. Tissue expansion was utilized for breast reconstruction when the remaining muscle and skin following modified radical mastectomy was insufficient to accommodate a prosthesis that matched in size and shape the opposite breast. All expanders were placed beneath an investing muscular pocket created by elevating the pectoralis major and serratus anterior. Postoperative expansion began within 1 week, and the breast was expanded to double the volume of the opposite breast. Twenty-two patients have completed their reconstruction with a mean follow-up in 7 months. There were nine complications, including five deflations and four infections. All patients have remained Baker I or Baker II. Creating ptosis to match the breast was accomplished by placing the expander below the rectus fascia and superiorly advancing this expanded tissue at the time of prosthesis placement. Primary breast reconstruction with tissue expansion following modified radical mastectomy is safe, simple, and produces a breast with excellent shape, size, texture, and patient satisfaction.     

Repair of Abdominal Wall Defects with Biodegradable Laminar Prostheses: Polymeric or Biological?

Introduction

Biological and synthetic laminar absorbable prostheses are available for the repair of hernia defects in the abdominal wall. They share the important feature of being gradually degraded in the host, resulting in place the formation of a neotissue. This study was designed to assess the host tissue’s incorporation of collagen bioprostheses and a synthetic absorbable prosthesis.

Methods

Partial defects were created in the abdominal walls of 72 New Zealand rabbits and repaired using collagen bioprostheses Tutomesh® and Strattice® or a synthetic prosthesis Bio-A®. Specimens were collected for light microscopy, collagens gene and protein expression, macrophage response and biomechanical resistance at 14, 30, 90 and 180 days post-implantation.

Results

Tutomesh® and Bio-A® were gradually infiltrated by the host tissue and almost completely degraded by 180 days post-implantation. In contrast, Strattice® exhibited material encapsulation, no prosthetic degradation and low cell infiltration at earlier timepoints, whereas at later study time, collagen deposition could be observed within the mesh. In the short term, Bio-A® exhibited higher level of collagen 1 and 3 mRNA expression compared with the two other biological prostheses, which exhibited two peaks of higher expression at 14 and 90 days. The expression of collagen III was homogeneous throughout the study and collagen I deposition was more evident in Strattice®. Macrophage response decreased over time in biomeshes. However, in the synthetic mesh remained high and homogeneous until 90 days. The biomechanical analysis demonstrated the progressively increasing tensile strength of all biomaterials.

Conclusions

The tissue infiltration of laminar absorbable prostheses is affected by the structure and composition of the mesh. The synthetic prosthesis exhibited a distinct pattern of tissue incorporation and a greater macrophage response than did the biological prostheses. Of all of the laminar, absorbable biomaterials that were tested in this study, Strattice® demonstrated the optimal levels of integration and degradation.     

Preservation of a digital osteotendinous structure with an omental flap

Taking into account the angiogenic properties of the omentum to revascularize ischemic tissues, this experimental, longitudinal, prospective, double-blind study in rabbits was designed to revascularize and preserve the mobility of a digital osteotendinous structure surgically devascularized in advance and to compare such omental angiogenic ability with that of the muscle and the panniculus carnosus. Thirty New Zealand rabbits were used. Three toes from the hind feet were surgically amputated from each rabbit. The skin was removed, exposing the bones, tendons, ligaments, and joints, to form what we termed the osteotendinous structure. Through a median laparotomy, the first part of each rabbit's own osteotendinous structure was placed inside the panniculus carnosus (group I), the second under the rectus abdominis muscle (group II), and the third was wrapped in a pediculate omental flap (group III). Three weeks later, each structure was assessed clinically for mobility and fibrosis and microscopically for fibrosis, newly formed vessels, viability, and tissue regeneration. Clinically, the group I structures showed a greater amount of fibrosis. The structures in groups II and III showed minimal fibrosis in all but four cases, which showed moderate fibrosis. Differences in joint mobility were assessed with the Kruskal-Wallis test. There was a statistically significant difference in mobility for the structures from group III, which was higher, followed by those from groups II and I. The exception was the proximal interphalangeal joints in groups II and III, for which the differences had no statistical significance. Microscopically, fibrosis and tissue necrosis were intense in the structures in group I, moderate in the group II structures, and mild in the group III structures. Conversely, vessel neoformation and tissue regeneration were intense in the structures in group III, moderate in group II, and were nil in group I. This study confirms with statistical significance that, in the rabbit, the omentum has a higher ability to revascularize degloved tissues than do the muscle and the panniculus carnosus, thus preserving a higher joint and tendon mobility. Consequently, it is suggested that a free omental flap be used in the treatment of ring avulsion injuries that lead to degloving of the digits.     

Effect of Processing on the Microflora of Norwegian Seaweed Meal, with Observations on Sporendonema minutum (Høye) Frank and Hess

Meal from the brown seaweed Ascophyllum nodosum (L.) Le Jol. is mainly used as an animal feed supplement. Since moist weed often develops a marked mold growth and since little was known about the microflora of seaweed meal, a cultural procedure was developed to enumerate the populations of bacteria, yeasts, and molds of seaweed meals manufactured by different drying processes. The microflora could be supported by a variety of media varying in levels of nutrition and in the source and concentration of salts. Fresh weed contained less than 10(3) bacteria and less than 10(2) yeasts and molds per g (dry weight). The type and extent of microbial populations in seaweed meal appeared to be dependent upon the method of seaweed drying. Rotary drum-drying at temperatures decreasing from 800 to 80 C maintained or reduced the microbial populations to 10(3) organisms per g (dry weight). Although meals with high nutritional quality can be obtained with warm air- or rock-dried weed, these conditions can also permit bacterial and mold development. Extended rock-drying in variable weather conditions and prolonged storage of moist weed, both of which decrease the nutritional quality, also lead to high bacterial numbers and to a marked development of the halophilic brown mold Sporendonema minutum which attained populations of 10(8) viable spores per g of dried weed. A poultry diet containing 5% badly molded weed had no apparent toxic or growth-depressing effect when fed to chicks.     

Effect of Processing on the Microflora of Norwegian Seaweed Meal,with Observations on Sporendonema minutum (H?ye) Frank and Hess

Meal from the brown seaweed Ascophyllum nodosum (L.) Le Jol. is mainly used as an animal feed supplement. Since moist weed often develops a marked mold growth and since little was known about the microflora of seaweed meal, a cultural procedure was developed to enumerate the populations of bacteria, yeasts, and molds of seaweed meals manufactured by different drying processes. The microflora could be supported by a variety of media varying in levels of nutrition and in the source and concentration of salts. Fresh weed contained less than 10³ bacteria and less than 10² yeasts and molds per g (dry weight). The type and extent of microbial populations in seaweed meal appeared to be dependent upon the method of seaweed drying. Rotary drum-drying at temperatures decreasing from 800 to 80 C maintained or reduced the microbial populations to 10³ organisms per g (dry weight). Although meals with high nutritional quality can be obtained with warm air- or rock-dried weed, these conditions can also permit bacterial and mold development. Extended rock-drying in variable weather conditions and prolonged storage of moist weed, both of which decrease the nutritional quality, also lead to high bacterial numbers and to a marked development of the halophilic brown mold Sporendonema minutum which attained populations of 10⁸ viable spores per g of dried weed. A poultry diet containing 5% badly molded weed had no apparent toxic or growth-depressing effect when fed to chicks.