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At least 19 recordsLinked to original sources
PubMed1978

[Flocculant interaction with native antibiotic solutions. The effect of flocculants on the quality indices of native solutions as dependent on a number of factors].

Flocculants had a significant effect on the characteristics of the fermentation broth filtrates of some antibiotics. They decreased the filtrate turbidity, concentration of the organic ballast, etc. The size of the floccules depended on a number of factors, including the fluocculant concentration, agitation rate, concentration of the dispersing phase in the initial filtrate. The optimal concentration of the flocculant was defined not only by the type of the antibiotic-producing organism but also by composition of the nutrient medium used for the biosynthesis. Floccculant treatment provided a significant increase in the quality of the fermentation broth filtrates with respect to the main parameters: levels of proteins, pigments, emulgation capacity.

Anti-Bacterial Agents↗
PubMed1976

Role of wall phosphomannan in flocculation of Saccharomyces cerevisiae.

Treatment with 60% hydrofluoric acid (HF) removed most of the phosphorus and small amounts of mannan, glucan and protein from walls of two non-flocculent strains (NCYC366 and NCYC1004) and two flocculent strains (NCYC1005 and NCYC1063) of Saccharomyces cerevisiae. Organisms of all strains showed increased flocculating ability following HF treatment. Flocculation of untreated organisms of NCYC1005 and NCYC1063, and of HF-treated organisms of all four strains, declined appreciably when they were washed in deionized water, with or without EDTA, and the flocculation was measured in deionized water instead of in 0-05 M-sodium acetate containing Ca2+. Treatment with 1,2-epoxypropane also caused a decrease in the flocculating ability of these organisms. Extracting the lipids from organisms of strains NCYC366 and NCYC1004 had no effect on their flocculating ability, but decreased the flocculating ability of organisms of strains NCYC1005 and NCYC1063. pH-electrophoretic mobility curves of untreated and HF-treated organisms confirmed the loss of wall phosphate by HF treatment, and indicated that HF treatment had little effect on the content of protein carboxyl groups in the outer wall layers. Mannose at 0-22 M completely prevented floc formation by organisms of strain NCYC1063; but, even at 0-33 M, it had very little effect on floc formation by HF-treated organisms of strains NCYC366 and NCYC1063. Organisms of all four strains bound fluorescein-conjugated concanavalin A to the same extent after treatment with HF as before, but this treatment led to a greatly diminished binding of of fluorescein-conjugated antiserum raised against organisms of strain NCYC366. The results indicate that phosphodiester linkages in yeast-wall mannan are not involved in bride formation through Ca2+ during floc formation and that this arises principally through carboxyl groups.

Binding Sites, Antibody↗
PubMed2026

Moderate expression and activity of flocculins underlie the characteristic flocculation phenotype of Saccharomyces pastorianus.

Flocculation is a key technological trait in lager brewing, governing fermentation performance, yeast recovery, and beer quality. In the allo-aneuploid hybrid yeast Saccharomyces pastorianus, the genetic basis of flocculation remains poorly resolved due to its complex dual sub-genome architecture. Here, we systematically re-annotated and functionally characterized the complete FLO gene repertoire of the Group II strain CBS 1483. Thirteen FLO genes were identified, including allelic variants and a previously uncharacterized adhesin, Flo12, containing a Hyphal_reg_CWP domain instead of the canonical PA14 lectin-binding domain. Structural modeling revealed strong conservation of Ca²+-binding residues in PA14 domains, alongside repeat-region diversification likely contributing to functional variability. Using optogenetic expression in a FLO-null background, we demonstrated that SpcI-FLO9-1 and SpcI-FLO9-2_1 are the strongest drivers of flocculation, exhibiting NewFlo-like sugar sensitivity. Transcriptomic analysis during 17°P wort fermentation showed dynamic induction of these genes coinciding with flocculation onset. Surprisingly, deletion of both loci in CBS 1483 did not abolish but only delayed sedimentation in wort, accompanied by improved maltose utilization and attenuation. These findings reveal functional redundancy and compensatory mechanisms within the FLO network of lager yeast, highlighting the genetic complexity underlying flocculation, and providing a molecular framework to inform yeast selection, strain development, and optimization of the lager fermentation processes.IMPORTANCEFlocculation, the process by which yeast cells aggregate and settle, is essential for producing clear, high-quality lager beer, and for efficient yeast recovery during brewing. However, the genetic basis of this trait in lager yeast has remained poorly understood because these strains possess unusually complex hybrid genomes. In this study, we systematically identified and characterized the complete set of flocculation genes in the industrial lager yeast Saccharomyces pastorianus CBS 1483. We demonstrated that lager yeast flocculation is not controlled by a single dominant gene, but instead emerges from the combined action of several moderately active adhesion proteins that are expressed at low levels during fermentation. Surprisingly, deleting the two strongest candidate genes only delayed, rather than eliminated, sedimentation, revealing a robust compensatory network that preserves brewing performance. These findings refine the current understanding of yeast flocculation and provide a molecular framework for developing brewing strains with improved fermentation efficiency, product consistency, and flavor quality.

Saccharomyces pastorianus↗
PubMed2026

Inducible flocculation in Komagataella phaffii enables enhanced biomass separation for biopharmaceutical production.

Biomass separation represents a critical bottleneck in Komagataella phaffii-based biopharmaceutical processes, as typically high cell densities of 40 - 50 % create significant operational, technical and economic challenges for harvest operations. Yeast cell aggregation (flocculation) provides a solution to accelerate cell sedimentation by increasing particle size, thus allowing to improve biomass-supernatant separation efficiency during both natural gravity settling and (continuous) centrifugation operations. This study demonstrates successful engineering of K. phaffii strains with an inducible flocculation phenotype using CRISPR/Cas9-based genome editing to integrate the Saccharomyces cerevisiae FLO1 (ScFLO1) gene under control of various regulatory elements, including methanol-inducible and derepressible promoters. Flocculation strength could be enhanced by implementing transcriptional positive feedback circuits based on the methanol-inducible AOX1 promoter. To address methanol-free production requirements, we developed alternative systems to retrofit PAOX1-based ScFLO1 expression and exploited the derepressible PDF promoter, offering broader compatibility with biopharmaceutical manufacturing facilities. Flocculating cells cultivated in a bioreactor demonstrated significantly improved sedimentation behavior, with considerably lower supernatant turbidity after short low-speed centrifugation or gravity sedimentation compared to non-flocculating controls. Crucially, cell flocculation had no negative impact on product amount and quality when expressing a multivalent NANOBODY® VHH molecule with pharmaceutical relevance. Thus, this work establishes the first genetically engineered flocculation system in K. phaffii compatible with recombinant protein production, providing the basis for an innovative approach to streamline harvest operations in biopharmaceutical processes.

Flocculation↗
PubMed1977

The identification, characterization, and mapping of a gene for flocculation in Saccharomyces sp.

Genetic studies of a flocculent haploid strain of Saccharomyces have revealed the flocculation to be dominant and controlled at a single gene locus. The flocculation character of both hybrids and haploids derived from such hybrids appears to be influenced by the repression or derepression status of the culture. Mapping studies of this flocculation gene have revealed that it is linked to ade 1 and therefore located on Chromosome I. Consequently, this is a different gene to the three flocculation genes studied by other laboratories because they have found such genes to be unlinked to ade 1. The flocculation gene being discussed in this paper has been designated FLO4. FLO4 has been located 32-33 cM from the Chromosome I centromere and 37 cM from ade 1 (i.e., FLO4 is on the opposite side of the centromere to ade 1).

Chromosome Mapping↗
PubMed1979

Changes in electrophoretic mobility and lytic enzyme activity associated with development of flocculating ability in Saccharomyces cerevisiae.

Cells from stationary-phase cultures of two strains of Saccharomyces cerevisiae (3 and 20) failed to flocculate when grown in a complex or a chemically defined medium, while those of two other strains (11 and 13) flocculated when grown in either medium. Strain 30 flocculated when grown in complex but not defined medium and harvested from stationary-phase cultures. pH-electrophoretic mobility measurements on all five strains showed that mobility attributable to carboxyl groups usually increased as cultures progressed from the exponential to the stationary phase, while that caused by phosphate groups tended to decline. Acquisition of flocculating ability was accompanied in strains 11 and 30 by a slight increase in amidase activity, and greater increases compared with nonflocculent populations in activities of leucine aminopeptidase. alpha-mannosidase, and proteinase C. Activities of proteinases A and B showed no correlation with acquisition of flocculating ability.

Amidohydrolases↗
PubMed1978

Flocculation and adsorption of enzymes during growth of a moderate halophile, Micrococcus varians var. Halophilus.

Flocculation of a moderate halophile, Micrococcus varians ATCC 2197, occurred during growth in complex medium containing 3 M NaCl and a concentration of MgSO4 and KH2PO4 greater than 40 and 14 mM, respectively. Extracellular nuclease activity was absent in the flocculated cultures. Repeated washing of flocs by Mg2+-free Tris buffer containing 3 M NaCl, lowering of pH value of floc suspension below 6.3, or addition of ethylenediaminetetraacetic acid resulted in complete dissociation of the flocs and release of Mg2+ ions as well as nuclease and amylase. Inhibition of extracellular enzyme production accompanied by flocculation appeared to be the result of adsorption of enzyme proteins to surfaces of the flocs, but not of inhibition of biosynthesis. Floc formation could also occur in media containing 18 mM CaCl2 and 3.0 mM KH2PO4, but the Ca flocs were not deflocculated by washing with Ca2+-free buffer, suggesting that the affinity of Ca2+ for cell envelopes was stronger than that of Mg2+. It was also observed that most halophilic Planococcus and Micrococcus flocculated in the presence of MgSO4 and phosphate but halophilic Pseudomonas, Acinetobacter, and Bacillus did not.

Adsorption↗
PubMed1976

Controlled flocculation of coarse suspensions by colloidally dispersed solids I: Interaction of bismuth subnitrate with bentonite.

Deflocculated suspensions of coarse powders tend to cake as the individual particles settle out and form compact, cohesive sediments. Limited flocculation results in looser sediments because the settled-out flocs incorporate large amounts of the liquid suspending medium. Controlled flocculation of bismuth subnitrate suspensions was achieved by the addition of small amounts of bentonite. The interaction of the coarse, positively charge bismuth subnitrate particles in aqueous suspension with negatively charged, colloidally dispersed bentonite was investigated by measuring electrophoretic mobility, sedimentation volume, and viscosity. Gradual addition of bentonite dispersion to bismuth subnitrate suspensions first reduced the zeta-potential of the bismuth subnitrate particles from +28 mv to zero, then inverted it, and finally caused it to level off at -20 mv for bismuth subnitrate-bentonite weight ratios below 200. Owing to the much greater specific surface area of bentonite, the surface of the bismuth subnitrate lath-shaped crystals was completely covered by 0.5% of its weight in clay platelets. Adhesion was promoted by electrovalences between surface bismuthyl ions and cation-exchange sites of the clay and by secondary valences. The charge neutralization of bismuth subnitrate by bentonite was a heterocoagulation process: the addition of small amounts of the clay flocculated the bismuth subnitrate suspensions and eliminated caking. While the zeta-potential of the bismuth subnitrate particles leveled off when their surface was saturated with bentonite platelets, sedimentation volume and viscosity continued to increase when the clay concentration was increased further while maintaining the bismuth subnitrate concentration constant. The excess, nonadsorbed bentonite formed the characteristic house-of-cards structure, incorporating the bentonite-coated bismuth subnitrate particles as cornerstones.

Bentonite↗
PubMed1978

[About the importance of chemical flocculation of wastewater in regard to hygienical aspects (microbiological and virological examinations in a wastewater treatment plant) (author's transl)].

In a small wastewater treatment plant corresponding samples from the intake and outtake of the chemical flocculation were chemically, microbiologically and virologically investigated and compared. It was found that both, the plate count and the number of coliforms, decreased about 90% to 95%. The phosphate content went down about 88%. The BOD5 reduction was ca. 80%, the COD reduction ca. 50%. Poliomyelitisviruses were found regularly in the intake but never in the outtake. Specially in regard to the high plate count- and virusreduction the chemical flocculation seems to be remarkable from the hygienical point of view not only for limnic but also for coastal waters.

Escherichia coli↗
PubMed1978

[Use of an immunofluorescence method and a flocculation test with DNA-sensitized bentonite particles in the serodiagnosis of disseminated lupus erythematosus (SLE)].

The determination of antibodies against native DNA is of great importance in the solution of the diagnostic and therapeutic problems of dissiminated lupus erythematodes. The practical results are in a direct dependence on the laboratory methods for their determination. The diagnostic significance of two methods was studied with the present investigation: indirect immunofluorescent test and flocculation test with DNA-sensibilized bentonite particles. Under the conditions of the investigation, with the aid of the first method, antibodies against native DNA were found in 86.1 per cent of the sera of lupus nephropathy patients as well as in 13.3 per cent of the sera of patients with renal diseases not associated with LED. High serum titres including up to 1/128, were observed only in LED cases. The continuous persistence of antibodies against LED is also characteristic for the latter. The flocculation test was positive in 60.7 per cent of the sera investigated only with LED cases. The conclusion is that both methods could more wisely be used in LED immunodiagnostic because they combine high sensitivity with specificity of reaction, are easy to perform and no expensive material and apparatuses are required.

Adolescent↗
PubMed1978

Physicochemical properties of glycyrrhizic acid in aqueous media II: Effect on flocculation-deflocculation behavior of suspensions of sulfathiazole and graphite.

The flocculation-deflocculation behavior of sulfathiazole and graphite in aqueous solutions of glycyrrhizic acid was studied by measuring the sedimentation volume and turbidity of supernates. The dispersing effect of glycyrrhizic acid on suspension of sulfathiazole showed a maximum in the pH 3-4 region, the same pH region where the zeta-potential of sulfathiazole particles showed a negative maximum. The results were explained by the variation of degrees of ionization of glycyrrhizic acid and sulfathiazole with pH. With graphite suspensions, the pH region where the dispersing effect of glycyrrhizic acid showed a maximum shifted to a higher pH compared with sulfathiazole. This result can be attributed to the fact that graphite is a nonpolar substance so the surface properties are not affected by a pH change. Hence, the adsorption of glycyrrhizic acid occurs even in a fairly high pH range.

Adsorption↗
PubMed1976

Exopolymer production and flocculation by zoogloea mp6.

Flocculation by Zoogloea MP6 was accompanied by the production of a mucopolysaccharide exopolymer. Polymer formation was initiated in mid-logarithmic growth phase, and the quantity produced appeared to be influenced by the level of carbon and nitrogen in the culture medium.

Amino Sugars↗
PubMed1979

[Present-day serological diagnosis of syphilis: comparison of TPHA and FTA-ABS tests with classical flocculation and complement-fixation reaction (author's transl)].

Twelve laboratories in the north Rhine-Westphalia participated in comparing TPHA and FTA-ABS tests with the so-called classical syphilis reactions (VDRL test, cardiolipin and pallida complement-fixation reaction, as well as Meinicke clearing reaction II). TPHA and FTA-ABS tests proved to be superior to the conventional methods both as regards specificity and sensitivity. Present-day serological tests of syphilis can thus be limited to the TPHA test to exclude syphilis, the FTA-ABS test as a confirmatory reaction and the VDRL test to judge the need or effectiveness of antisyphilitic treatment. These reactions which supersede the conventional syphilis tests serve for rational, reliable and cheap serological diagnosis of syphilis.

Cardiolipins↗