Surface Slime Research Articles

Influence of starter cultures of lactic acid bacteria on microbiological parameters and shelf life of sausages

The main spoilage microorganisms of the vacuum-packaged sausages on the first day of chilled storage are the bacteria of the following families: Enterobacteriaceae (Raoultella planticola, Raoultella ornithinolytica, and Citrobacter freundii), Morganellaceae (Morganella morganii) and Staphylococcaceae (Macrococcus caseolyticus), and at the end of the shelf life (on the twenty-first day) - Enterobacteriaceae (Proteus mirabilis, Moellerella wisconsensis and Serratia liquefaciens). An appearance of cloudy juice, surface slime and delamination of the vacuum packaging characterises the sausage spoilage. QMAFAnM in the sausages was increased by 1.09 lg CFU/g and 1.53 lg CFU/g on the first day of storage, by 1.18 lg CFU/g and 1.54 lg CFU/g on the twelfth day, by 0.92 lg CFU/g and 1.96 lg CFU/g on the eighteenth day, respectively, compared to the control sample, because “Vienna sausages with chicken fillet” were treated with starter culture SafePro BLC-48 (Lactobacillus curvatus) or the mixture of starter cultures SafePro BLC-48 (Lactobacillus curvatus) + Bactoferm Rubis (Lactococcus lactis subsp. Lactis) before vacuum packaging. Because the sausages were treated with the mixture of starter cultures SafePro BLC-48 + Bactoferm Rubis, the lactic-acid microorganisms were increased by 0.63 lg CFU/g and 0.53 lg CFU/g on the twenty-fifth and thirtieth days, respectively, compared to the sausages that were treated with SafePro BLC-48. During the entire shelf life, no pathogenic and opportunistic pathogenic bacteria, in particular S. aureus, L. monocytogenes, Salmonella spp., E. coli, coliform bacteria, as well as yeast and mold, were detected in the sausages under all treatment options. The use of starter culture SafePro BLC-48 (Lactobacillus curvatus) or the mixture of starter cultures SafePro BLC-48 (Lactobacillus curvatus) + Bactoferm Rubis (Lactococcus lactis subsp. Lactis) increases the shelf life of the vacuum-packaged sausages if they are kept in a refrigerator for up to 30 days, which is 12 days longer than their shelf life without treatment. The sausage treatment with the mixed starter cultures of the lactic-acid microorganisms may be promising if the development of the aerobic spoilage bacteria is confirmed.

Changes of sensory atributes of chilled vacuum-packaged cold-smoked common carp (Cyprinus carpio) and cold-smoked bighead carp (Hypophthalmichthys nobilis) fillets

The aim of this research was to monitor changes of selected sensory properties and instrumental colour parameters (L*, a*, b*) of vacuum-packaged cold-smoked common carp (Cyprinus carpio) and cold-smoked bighead carp (Hypophthalmichthys nobilis) fillets during storage at 3 ? 0.5?C and to determine the shelf life of the products. Sensory tests and instrumental color determination were performed on days 1, 7, 10, 12, 14, 15, and 16 of storage. All estimated sensory characteristics of common carp samples received significantly lower (P < 0.05) score on day 15. ?Musty? odour of common carp samples detected on day 16 caused that odour score was below the acceptability limit of 2. On the last day of experiment, reduced intensity of pink cream colouring of carp muscle was observed together with softened texture and surface slime. A decrease of scores of the sensory attributes of cold-smoked bighead carp fillets was observed throughout the storage period. However, all estimated sensory characteristics were within the acceptability level. Significant increase (p < 0.05) of L* value was noted in both group of samples, while redness (a*) and yellowness (b*) remaid quit stable during the storage. Based on the sensory results, it was concluded that vacuumpackaged cold-smoked common carp samples remained acceptable for up to 15 days of storage, whereas vacuum packaged cold-smoked bighead carp samples remained unchanged until the end of the experiment.

High CO2-modified atmosphere packaging for extension of shelf-life of chilled yellow-feather broiler meat: A special breed in Asia

This work evaluated the effect of air- and modified atmosphere-packaging (MAP) on the shelf life of chilled yellow-feather chicken, which is a special breed in China. Fresh half-carcasses were stored in air and under modified atmosphere packaging (M-H: 80% CO2/20% N2 and M-L: 30% CO2/70% N2) at 4 °C for up to 12 days. Microbiological, physico-chemical and sensory attributes were measured. The results showed that total viable counts (TVC) reached the limiting value (7.0 log CFU/g) after 4, 10 and 8 days of storage under aerobic, M-H packaging and M-L packaging conditions, respectively, while the sensory values (odor and surface slime data) and the percentage of drip loss were in good agreement with the trend for TVC. During the storage, the total volatile basic nitrogen (TVB-N) content of broiler meat in MAP packaging was lower than that in air-packaging, however, the M-H group had the highest storage losses. In conclusion, high CO2 (80%) concentration packaging prolonged the shelf-life by at least 6 days when stored at 4°C. Our results provide practical information to extend the shelf-life of chilled yellow-feather broiler meat, which will benefit the poultry industry by reducing unnecessary waste.

Shelf life of boiled restructured buffalo meat rolls in refrigerated storage under vacuum packaging condition

Cooked restructured buffalo meat rolls prepared from restructuring process were stored at 4 ± 1°C in polyethylene terephthalate laminated with polythene pouches under vacuum packaging condition. The samples were evaluated for physicochemical parameters, microbial quality and sensory attributes at regular intervals of 0, 5, 10, 15, 25 and 30 days of storage. A significant decrease in pH, extract release volume values, was observed with increasing storage period. Overall days mean for moisture decreased with increasing storage period, however, no significant difference in overall days mean for moisture content was observed on from day 0 to day 30 of storage. A significant (P < 0.01) increase in thiobarbituric acid value and tyrosine value was observed with increase in storage period. Microbiological counts increased with the advancement of storage period. However, throughout the storage period, all microbial counts were within the acceptable limits of cooked meat products. Boiled restructured buffalo meat rolls did not show any symptoms of spoilage such as off odour and surface slime on day 30 of storage and were acceptable for sensory quality up to 30 days of refrigerated storage (4 ± 1°C) under vacuum packaging. Thus, the present study indicates that vacuum packaging could be used as a way to improve the shelf life of boiled restructured buffalo meat rolls without affecting the physicochemical, microbiological and sensory qualities of the products.

Achene micromorphology of seven taxa of Achillea L. (Asteraceae) from Turkey

Micromorphological characters of achenes in seven taxa of Turkish Achillea L. (Asteraceae) were investigated using stereomicroscope and scanning electron microscope (SEM). Some morphological descriptions of achenes were given for each species. A.biserrata Bieb. has the biggest (0.69±0.092 x 2.01±0.252 mm) and A. grandiflora Friv. has the smallest (0.30±0.018 x 1.12±0.058 mm) achenes. The achenes are oblong-lanceolate in A.biserrata and A. teretifolia Willd. and they are oblong in the remaining taxa. In surface sculpturing, the ornamentation and slime cell distribution varied among the taxa. However, A. biebersteinii Afan. has distinct slime cells forming groups scattered over the achene surface. Mature achenes are ribbed and glabrous in all studied taxa. A. biserrata has distinct carpopodium structure.DOI: http://dx.doi.org/10.3329/bjpt.v21i1.19253Bangladesh J. Plant Taxon. 21(1): 19-25, 2014 (June)

Morphometric analysis of caryopsis in some species of Eragrostis (Poaceae)

Seed exomorphic characters of nine different species of Eragrostis were investigated by Light and Scanning electron microscopy. In the present study the micro-morphological characteristics features of caryopses such as shape, dimension, colour, epidermal cell surface structure and features of anticlinal and periclinal walls have been carried out. Light microscopy revealed that most of the studied caryopses varied in shape from oblong to ovate/ ovoid. The caryopsis in most of the species of Eragrostis are sticky in nature due to the presence of surface slime cells, which makes them appear shiny and transparent. This morphological feature could only be observed under SEM. The nine different species could be differentiated on the basis of shape and position of the hilum and embryo.

Marinade Composition and Vacuum Effects on Liquid Uptake and Retention in Tumbled Fish Portions

A combination of higher pH (pH 8 vs. pH 6 or 7), higher NaCl content (6% vs. 2%), and shorter chain polyphosphates (sodium tripoly- or pyro-phosphate vs. hexametaphosphate, all at 1.6% in the marinade) during tumbling of halibut pieces (uniform size, shape) resulted in greatest marinade uptake and yields following subsequent purge and cook losses. Surface slime formation noted in optimum treatments, likely the result of increased surface extraction of protein, could dictate moderating ionic strength and solution pH as a marketing consideration. Unfrozen (fresh) fish exhibited a greater uptake of marinade than previously frozen fish, but also higher subsequent purge and cook losses such that yields after cooking for the two treatments were similar. Contrary to conventional industry belief, vacuum (9.2 kPa) during tumbling did not affect uptake of marinade.

Observations and experiments on extending shelf-life of ?rockfish? (Sebastes spp.) products with ozone

On a fishing vessel and in the laboratory, trials were undertaken to study the effect of ozonation on rockfish bacteria (Sebastes spp.) during transport from fishing grounds. At the beginning of the experiment, bacterial loads were the same on ozone-treated and control samples. Fish transported in ozonated water lost some of their bacterial film with surface slime when they were pumped from the boat's hold into the processing plant. Ozonation appears to encourage the detachment of the surface slime and bacterial film by partly oxidizing the excess slime excreted during capture. When ozonated intermittently during transport the fish shelf-life was extended by about 36 h. The same ozonation treatment was simulated in the laboratory which revealed higher bacterial counts on the ozonated fish than on the control samples. Fish used in this trial are believed to have been stored for several days prior to ozonation. This storage may have resulted in changes in the properties of the surface slime, counteracting the effect of ozonation.

Types of reproductive cell in Exidia recisa and Sirobasidium intermediae

In Exidia recisa basidiospores germinated on agar to give a branched mycelium with prostrate conidiophores forming bacilliform conidia in succession as from a phialide. The situation is compared with that in other heterobasidiomycetes. In Sirobasidium intermediae basidia were formed in basipetal succession. The basidia liberated spore-like epibasidia (sterigmata) which accumulated in large numbers as a surface slime on the basidiocarp. The very few epibasidia that germinated in situ gave rise to aerial ballistosporic basidiospores which, on agar, germinated to give a yeast phase. Spread thinly on agar, most epibasidia germinated in a variety of ways; many gave rise to aerial ballistospores; others to a yeast phase; and a few underwent repetition to form sessile blastospores. Yeast-like colonies, arising from discharged basidiospores, developed occasional aerial tufts of clamped hyphae which, on isolation, grew slowly and soon reverted to the yeast phase. In forming a yeast-like phase and in not producing conidia as from a phialide, Sirobasidium seems closer taxonomically to Tremella than to other tremellaceous fungi.

Behaviour of zoospores and zoospore cysts in relation to root infection by Pythium aphanidermatum

summaryThe Pre‐Penetration Sequence Involving Zoospore Taxis, encystment, Cyst Germination And Germ‐Tube Orientation Was Studied By Video Microscopy When Roots Of Wheat, Cress or Tomato Were Placed In Suspensions of Zoospores of Pythium aphanidermatum (Edson) Fitzp. The Sequence Was Also Studied In Vitro, to identify the responsible Factors.Several amino acids, sugars or volatile compounds elicited one of more stages of the sequence, but only glutamic acid and aspartic acid elicited all stages and thus could account for the observed behaviour on roots. Polyuronates of root surface slime also may be needed for encystment and orientation of Spores, because germ‐tubes emerged towards roots from a fixed point near the former position of the water‐expulsion vacuole. However, identical patterns of zoospore accumulation and encystment on untreated roots and roots encased in alginate gel indicated that neither polyuronates nor Specific sugar residues of root slime caused localized encystment on roots.Based on these results, a ‘simplest case’ model of the pre‐penetration sequence on roots is proposed.

Molecular Aspects of Bacterial Adhesion, Colonization, and Development of Infections Associated with Biomaterials

Staphylococcus aureus and coagulase-negative staphylococci of species commonly isolated from biomaterial-associated infections commonly express fibronectin-binding surface proteins and the ability to interact with collagen. These findings, as well as the ability of coagulase-negative staphylococci to produce surface slime or capsular material, are presented as alternative models for how biofilms develop on biomaterial surfaces. Further knowledge of how bacteria and eukaryotic cells interact with various biomaterials will stimulate the development of better tissue implant devices to avoid biomaterial-associated infections.

The reason for loss of agglutinability of Pseudomonas aeruginosa cells heated to 60 degrees C.

The loss of agglutinability of live Pseudomonas aeruginosa cells by mild heating to 60 to 80 degrees C is due to denaturation of surface slime, which can no longer combine with antibodies but is still attached to the cell surface and thus prevents access of antibodies to the cell wall. Prolonged boiling or autoclaving would not only denature the slime but also detach it from cell surface and thus make the cells accessible to antibodies directed to cell wall antigens. Heated cells are, however, no longer agglutinable by antibodies directed to slime antigens. After prolonged boiling or autoclaving, a large amount of polysaccharides appeared in the supernatant, and concomitantly, total cell volume as measured by turbidity of the cell suspension was significantly reduced.

Coagulase-negative staphylococcal adherence and persistence.

Coagulase-negative staphylococci, which are normal inhabitants of human mucous membranes and skin, have recently evolved as major contributors to systemic disease in hospitalized patients in the developed world [1]. Coagulase-negative staphylococci colonizing skin are capable of adherence to plastic and other therapeutic or prosthetic devices, and therefore, intensive-care patients or patients treated with reconstructive devices are especially susceptible to serious infections with these organisms. Staphylococcus epidermidis is the coagulase-negative species most frequently recovered from clinical specimens, although ^0 species of coagulase-negative staphylococci have been identified. At least two properties of S. epidermidis provide this organism with mechanisms for persistence. One of these properties is the capacity for adherence to surfaces by using lectins or other adhesins [2]. The other property is production of a surface slime material that protects the organisms from phagocytosis and from the action of antimicrobial agents [3]. Extracellular slime substance also inhibits inflammatory and specific adaptive immune responses [4, 5].

Scanning Electron Microscopy of Staphylococcus Epidermidis Adherence to Continuous Ambulatory Peritoneal Dialysis Catheters

Infections associated with the use of intravascular devices have been documented and have been reported to be related to duration of catheter usage. Recently, Eaton et al. reported that Staphylococcus epidermidis may attach to silastic catheters used in continuous ambulatory peritoneal dialysis (CAPD) treatment. The following study presents findings using scanning electron microscopy (SEM) of S. epidermidis adherence to silastic catheters in an in vitro model. In addition, sections of polyvinyl chloride (PVC) dialysis bags were also evaluated by SEM.The S. epidermidis strain RP62A which had been obtained in a previous outbreak of coagulase-negative staphylococcal sepsis at local hospitals was used in these experiments. The strain produced surface slime on exposure to glucose, whereas a nonadherent variant RP62A-NA, which was also used in these studies, failed to produce slime. Strains were grown overnight on blood agar plates at 37°C, harvested from the surface and resuspended in sterile saline (0.85%), centrifuged (3,000 rpm for 10 minutes) and then washed twice in 0.1 M phosphate-buffered saline at pH 7.0. Organisms were resuspended at a concentration of ca. 106 CFU/ml in: a) sterile unused dianeal at 4.25% dextrose, b) sterile unused dianeal at 1.5% dextrose, c) sterile used dialysate previously containing 4.25% dextrose taken from a CAPD patient, and d) sterile used dialysate previously containing 1.5% dextrose taken from a CAPD patient.

Translocation of Motile Cells of the Gliding Bacterium Cytophaga johnsonae Depends on a Surface Component that May Be Modified by Sugars

SUMMARY: Twenty-three sugars and sugar derivatives prevent the spread of colonies of the gliding bacterium Cytophaga johnsonae on 1–5% agar gels. Concentrations of sugars that inhibit colony spread have no inhibitory effect on motility or growth of cells. Observations of patterns of colony spread on plates with pre-established concentration gradients of sugars indicate that cells of C. johnsonae do not exhibit a chemotactic response to compounds that inhibit their spread. Inhibitory compounds were placed into three groups based on their relative effectiveness as inhibitors. Both metabolizable and non-metabolizable sugars served as inhibitors, it was not necessary for a sugar to be transported into the cell to inhibit, and the effectiveness of a sugar as an inhibitor did not correlate with its ability to support growth. The inorganic ions Mg2 °, Ca2 + and SO|∼ also inhibit colony spread on 1–5% agar gels. All the evidence taken together suggests that inhibitors of spread produce their effects by modifying the properties of a surface slime. The observations reported here help to give an experimental definition to two components of the gliding motility system of C. johnsonae: the motility ‘machinery* that is responsible for an actively moving cell surface and is not affected by the presence of sugars, and an extracellular component which is sensitive to sugars and which is required for translocation of cells with moving surfaces.

Cutaneous infections: Microbiologic and epidemiologic considerations

The normal bacterial flora of the skin represents an important host defense mechanism against invasion by potentially pathogenic organisms. This flora is primarily composed of aerobic diphtheroids (Corynebacterium species), anaerobic diphtheroids (Proprionobacterium acnes), and coagulase-negative staphylococci. Gram-negative bacilli may be present in limited numbers in intertriginous areas. Localized cutaneous infections occur in ostensibly normal hosts, often after trivial trauma, examples being streptococcal or staphylococcal impetigo, staphylococcal furunculosis, or more unusual infections due to agents such as Mycobacterium marinum. When the skin is injured more extensively by trauma, burns, ischemia with ulceration, or iatrogenic manipulations, or when host immunologic defenses are suppressed, more severe infections are likely to supervene, and the threat of systemic dissemination of infecting microorganisms increases. Cutaneous infection in immunosuppressed hosts may involve the same pyogenic bacteria that affect normal subjects or it may involve a variety of opportunistic invaders, including herpes viruses, gram-negative bacilli, mycobacteria, and deep or superficial mycoses. The skin may also be affected by infections whose primary site lies elsewhere in the body. Cutaneous manifestations may be secondary to hematogenous seeding of the causative agent or to the effects of toxins or immune complexes. Certain microbial agents may initiate a wide variety of cutaneous lesions, depending on route of infection and the status of the host. Thus, cutaneous lesions attributable to Pseudomonas aeruginosa range from “green nail syndrome” and self-limited folliculitis to ecthyma gangrenosum. Similarly, group A streptococci may produce pyoderma, cellulitis, lymphangitis, erysipelas, or scarlet fever. We recently described a syndrome of recurrent cellulitis in the saphenous vein donor extremities of patients who have undergone coronary artery bypass grafts. Most patients have associated tinea pedis. The pathophysiologic aspects of this syndrome are probably multifactorial, involving compromise of lymphatic or venous drainage, bacterial infection, elaboration of bacterial toxins, and hypersensitivity to bacterial or fungal products, or both. Coagulase-negative staphylococci are exhibiting a more prominent pathogenic potential than heretofore. When they infect immunosuppressed hosts or patients with indwelling intravascular catheters or cardiac prostheses, coagulase-negative staphylococci may cause life-threatening disease. A newly recognized, probable virulence factor in these bacteria is the elaboration of surface slime, a substance that facilitates adherence of the staphylococci to artificial surfaces. Slime production is present much more frequently in strains recovered from clinically significant bloodstream infections than in strains recovered from other sources. The clinical significance of surface slime is currently under intense investigation. Normal human skin plays an indispensable role in the protection of the host against a wide range of pathogenic microorganisms. The mechanics of this host defense system are incompletely understood, but they appear to depend, at least in part, on the barrier imposed by the intact keratin layer of the epidermis, the relative dryness of the skin surface, and the presence of normal, nonpathogenic cutaneous bacterial flora. Thus, patients at risk include those in whom (1) the surface integrity of the skin has been breached by trauma, surgical incision, or insertion of medical devices; (2) the skin has become moistened and macerated by constant contact with bodily secretions or by application of occlusive dressings; and (3) the usual bacterial flora has been ablated by antimicrobial therapy or other mechanisms. Moreover, processes that impede local arterial, venous, or lymphatic flow, or processes that suppress generalized host immunologic competence allow opportunistic pathogens to initiate significant local cutaneous infections. Finally, infected skin may be a source of systemic dissemination, and conversely, systemic infections may express themselves in a variety of cutaneous manifestations.

Carbohydrate mediation of the biological activities of the glycolipoprotein of Pseudomonas aeruginosa.

The glycolipoprotein (GLP) extracted from the surface slime of Pseudomonas aeruginosa produces effects in mice similar to those of the viable cell. The lethal activity has been located in the lipid moiety; however, degradation of the carbohydrate moiety with sodium metaperiodate reduced the antigenicity and abolished the lethality of the GLP. Similar degradation with a phage-induced polysaccharide depolymerase reduced the antigenicity only slightly but reduced the lethality over 60%. The neutral sugar composition of the isolated polysaccharide moiety was shown to be that of the parental GLP. Of the component neutral sugars, mannose and its derivatives were capable of inhibiting the agglutination of erythrocytes coated with GLP. Inhibition also occurred with a soluble mannose polymer from the cell walls of yeast. Antiserum to GLP and to its isolated polysaccharide moiety agglutinated yeast cells, whereas antiserum to a glycolipid fragment of the GLP lacking mannose did not. The lethality of the GLP was reduced by degradation with alpha-mannosidase or by blocking the mannose residues with concanavalin A, and the glycolipid fragment showed less lethality than the native GLP. We conclude that mannose, in addition to being an immunodominant sugar, is an effector sugar in the expression of GLP lethality.

Adhesion of fungal zoospores to root surfaces is mediated by carbohydrate determinants of the root slime

Adhesion of Phytophthora cinnamomi zoospores to Zea mays roots depends on the integrity of the carbohydrate component of the secreted root surface slime. Adhesion is abolished by periodate oxidation of the root surface, enzymic removal of terminal fucosyl residues of the slime and by interaction of the same residues with a fucose-binding lectin.

Lipids in the skin of a cat-fish Heteropneustes fossilis (Bloch) (Heteropneustidae, Pisces). A histochemical investigation.

Localization and characterization of different lipids in the cellular constituents of the skin of Heteropneustes fossilis has been made using several histochemical techniques. High contents of cholesterol, its esters and phospholipids have been correlated with the metabolically active state of the basal cells undergoing cell proliferation and differentiation. The polygonal cells in the outermost layer of the epidermis, though rich in phospholipid contain small amounts of cholesterol and its esters. This has been correlated with the metabolically less active state of theses cells. Neutral lipids and phospholipids in the polygonal cells of the outermost layer may contribute to the contents of surface slime and act as an efficient barrier for the penetration of water through the skin. The deposits of neutral lipids in the subcutis may provide energy during the period of fasting, act as a barrier for water diffusion through the skin and serve as shock absorbing pads protecting the fish from mechanical injury.

Protein Changes Caused by Bacterial Growth on Beef

Proteolysis could not be detected, prior to the appearance of spoilage odours and surface slime, in beef allowed to spoil aerobically at 5° with its own natural flora or after inoculation with a reconstituted freeze‐dried beef slime. Although the slime inoculum gave a final microbial flora similar to the naturally‐attained one, it resulted in more rapid and extensive post‐spoilage proteolysis. Pure culture experiments showed that proteolysis was probably due to the activities of Gram negative organisms.