A study on microbiology of biological film layer in rotating biological contactors

Experimental studies were carried out for upgrading the secondary treated domestic sewage effluent using the Rotating Biological Contactors (RBC) as an unit process in the premises of the existing water reclamation plant of Satellite Centre Building Complex of Indian Space Research Organisation at Bangalore. As part of these studies, a brief study was carried out on the microbiological aspects of the biological slime layer developed in the RBC. This study included observations on the development of the biological film on wetted disc surfaces of RBC, measurement of the thickness of the biological film, a discussion on significance of biofilm thickness in substrate removal, effect of wastewater characteristics on the thickness of biofilm and determination of MLSS/MLVSS ratio of biological film obtained in RBC reactor used for upgrading the secondary effluent. The results of these studies are presented in this paper. The results of identification of species of micro-organisms predominant in the biological slime layer in the RBC used for upgradation of secondary treated effluent are discussed separately in another paper.     

Cellular events in tolerance. VI. Neonatal vs adult B cell tolerance: differences in antigen-binding cell patterns and lipopolysaccharide stimulation.

The numbers and fate of antigen-binding cells (ABC) in neonatal and adult mice rendered tolerant to fluorescein (FL)-labeled heterologous gamma-globulins were studied. Similar numbers of FL-ABC were observed 1 day after tolerogen in both adult and neonatal mouse spleens: by 7 days after tolerization, no FL-ABC were observed in either case. Reinjection with FL-tolerogen at 7 days led to the detection of normal numbers of ABC in adult mice but significantly reduced numbers in neonates. This suggests that neonatal ABC either have been deleted or have failed to resynthesize surface receptors. Two weeks after tolerance induction, spleen cells from these tolerant mice were cultured with Escherichia coli lipopolysaccharide (LPS), a polyclonal B cell mitogen, or with specific antigen. Tolerant adult spleen cells made an equivalent anti-FL response to that of the uninjected controls when stimulated with LPS, but were unresponsive to specific antigenic triggering. In contrast, spleen cells from neonatally tolerized mice were unresponsive to either specific or nonspecific (LPS) stimulation. Thus, these neonatally tolerized spleen cells lose sensitivity to polyclonal-stimulating agents (along with their receptors), or more simply, are deleted.     

Cryopreservation-induced enhancement of interleukin-2 production in human peripheral blood mononuclear cells.

To better understand the effects of cryopreservation on various immunocompetent cell functions, we have examined the interleukin-2 (IL-2)-producing activities of frozen mononuclear cells (MNCs) from healthy subjects. The mechanisms responsible for the observed effects were also analyzed. Both the unfractionated and monocyte-depleted, frozen MNCs produced significantly larger quantities of IL-2 than fresh cells. Similar to freezing, L-leucine methyl ester (Leu-OMe) treatment (to eliminate IL-1 and prostaglandin E-2 (PGE-2)-secreting cells) also increased the IL-2-producing activities of fresh cells, but freezing no longer enhanced the production of IL-2 by Leu-OMe-treated cells, suggesting that (1) both the freezing process and Leu-OMe treatment have similar effects on IL-2 production, (2) the increased IL-2 secretion by frozen MNCs is independent of IL-1, and (3) inactivation of PGE-2-secreting cells during the freezing procedure is responsible for increased IL-2 secretion. Elimination of CD8+ T cells (putative suppressor cells) from MNCs has also resulted in the production of increased amounts of IL-2 by fresh cells, and again, freezing did not further enhance the IL-2-secreting activities of MNCs, that are devoid of CD8+ T cells. This confirms that the increased IL-2 production is due to the inactivation of immuno-down-regulatory cells. The results provide further evidence that the lack of active, suppressor T cells, monocytes, and increased IL-1 and -2 production may be responsible for the previously reported enhanced immunoglobulin-producing abilities of cryopreserved cells from healthy subjects and from patients with lung cancer.     

Preparation of protoplasts from the cyanobacterium Spirulina platensis and a novel viability assay

A method is described for the isolation of protoplasts from the cyanobacterium Spirulina platensis using an elite strain (S.pl. FT 06) selected after screening. Trichomes of the cyanobacterium were treated with lysozyme (0.1%) for 28 h at room temperature in 0.03 mol l^-1 phosphate buffer (pH 6.8) with 0.5 mol l^-1 mannitol as the osmoticum. This resulted in an 80% yield of protoplasts. Cells were intact in their fine structure and viable as evidenced by a rapid and efficient viability assay using a novel mixture of fluorescein diacetate and calcofluor white.     

Simplified production technology of blue green alga Spirulina platensis for feed applications in India

Summary A rural oriented methodology for the production of the blue green alga Spirulina platensis has been developed and practically evaluated on pilot plant scale (45 m²). The system suggested is almost free of electrical inputs or capital intensive equipment and designed to use maximal manpower. A production rate of 3 kg of dry algae per week can be achieved using 45 m² area.     

Irreversible inactivation of mammalian Δ5-3β-hydroxysteroid dehydrogenases by 5, 10-secosteroids. Enzymatic oxidation of allenic alcohols to the corresponding allenic ketones

Novel 4,5-allenic 3β-hydroxy-5,10-secosteroids have been synthesized by sodium borohydride reduction of the corresponding conjugated allenic 3-oxo-5, 10-secosteroids. The secosteroid allenic alcohols are substrates for bovine adrenal and human placental Δ⁵-3β-hydroxysteroid dehydrogenases, and the resulting electrophilic conjugated allenic ketones are shown to inactivate these dehydrogenases in a time-dependent manner. Inactivated enzyme did not recover activity after filtration through Sephadex G-25. In contrast, the secosteroid allenic alcohols were not oxidized at C-3 by the bacterial 3β(and 17β)-hydroxysteroid dehydrogenase from $\text{P. testosteroni}$, nor did the corresponding allenic ketones inactivate this enzyme when incubated directly.