Mineral Release Dynamics of Tricalcium Phosphate and Waste Muscovite by Mineral-Solubilizing Rhizobacteria Isolated from Indo-Gangetic Plain of India

The aim of the present investigation was to evaluate the mineral release abilities of ten rhizobacterial strains isolated from rhizosphere of various crops growing in the Indo-Gangetic Plain (IGP) of India. Their abilities to solubilize inorganic phosphorus (P) and potassium (K) minerals from insoluble tricalcium phosphate (TCP) and waste muscovite (WM) revealed that rhizobacteria significantly solubilized different levels of inorganic P and fixed K, respectively. Some of the rhizobacterial stains have the ability to produce ammonia, indole-3-acetic acid (IAA), and hydrogen cyanide (HCN). The identification based on the 16S rDNA gene sequencing of selected mineral-solubilizing rhizobacteria (MSR) having greater potential to serve as bioagents were identified as Bacillus subtilis (BRHU01, BRHU03, and BHU20), Bacillus tequilensis (BRHU02), Bacillus licheniformis (BRHU04), Bacillus pumilus (BRHU05), Bacillus flexus (BHU02), Brevibacillus formosus (BHU16), Bacillus methylotrophicus (BHU29), and Bacillus amyloliquefaciens (BHU30). Interestingly, inorganic P and K solubilization by these strains belonging to genera Bacillus and Brevibacillus showed significant variations from 0.52 to 14.49 and from 1.62 to 8.60 µg mL^?1, respectively. However, generally, pH values of culture media decreased from near neutral (6.43) to acidic (3.83) with increasing incubation period, and this was inversely correlated with quantities of K solubilized by these rhizobacterial strains. Meanwhile, the electrical conductivity (EC) of broth culture increased from 0.09 to 0.23 dS m^?1 with increasing incubation period. Principal component analysis (PCA) of the MSR revealed three clusters, which exhibited high variance with respect to nutrient release. Taken together, these results suggest that Bacillus and Brevibacillus sp. identified in this study solubilized varying levels of inorganic P and fixed K from insoluble TCP and WM by acidolysis mechanisms.     

Cross- species communication in bacterial world

Biofilms are the compact association of micro organisms and the communication processes in these biofilms are always a wonder. Electrical and chemical signaling mechanism are the key to understand the bacterial communication network. Quorum sensing so far has been able to explain the coordinated motion of bacteria through its chemical signaling mechanism. Bacteria residing within biofilm communities are trivial to communicate. But the recent observation in 2017 by Humphries et al. has revealed that the ion channels enabled electrical signaling mechanism can be as powerful as to attract the distant cells i.e., this signaling mechanism are capable of holding a long range behavior. As a result long range cross species communication in the bacterial world have been possible. This substantial outcome has brought this field into a new paradigm to investigate the complex co-existence of biofilm communities and distant cells with a possible scope of application in synthetic biology. In this present article, we briefly describe this new signaling mechanism and how it gives rise to a long range communication ability in bacterial communities.     

Prediction of tertiary structures in 'scorpion-toxin' type proteins.

In the three-dimensional architecture of macromolecules, the structural stability and proper folding manifest due to cooperative packing interaction of various segments. Hydrophobicity is the major factor stabilizing protein-protein associations. In the disulfide-containing proteins, S-S bonds are integral part of structural motifs and large part of the protein-folding problem can be reduced to identifying and understanding motifs and subdomains of these proteins. Identifying such a motif with S-S bonds in 'scorpion-toxin' type proteins, and from model-building studies, five tertiary structural models for these type of proteins can be proposed. These canonical structural models can be refined by regular minimum energy and computer simulation methods to arrive at the final tertiary structures. Such 'models' can be of considerable use i) in understanding the biochemical reaction mechanisms in the structure-function relationships, ii) structure determination by X-ray methods (molecular replacement method), iii) drug design etc.     

Application of alkaline elution, Fast Micromethod and flow cytometry in detection of marine contamination.

DNA damage is an inescapable aspect of life in the biosphere. The presented investigations were an attempt to examine the response of a DNA damage as a biomarker of environmental quality in the mussels Mytilus galloprovincialis sampled at differently contaminated areas of Istrian coast, Northern Adriatic. The investigations were performed in order to get information about the genotoxic risk for marine organisms exposed to mixed environmental pollution, as well as the information about the presence of unknown mixture of genotoxic contaminants in the marine environment. Types of DNA damage detected are alkali-labile sites and single-strand breaks measured by Fast Micromethod, interstrand cross-links and DNA protein cross-links by alkaline filter elution and cell cycle disturbation by flow cytometry. The applicability of all three methods for marine quality control is discussed.     

DYNAMICS OF LEUKOCYTE MIGRATION INTO THE MOUSE ASCITES TUMOR

There is a marked increase in the number of peritoneal leukocytes (lymphocytes, monocytes and granulocytes) during the growth of Ehrlich ascites tumor in mice. No local proliferation (as indicated by a labeling at 1 hr following a single ³H-TdR injection) was observed in the normal peritoneal leukocytes or those in the ascites tumor, except for a very minor labeling of some tumor macrophages. Kinetics of peritoneal leukocytes was studied with a series of twelve injections of ³H-thymidine (20 μCi every 8 hr) in normal mice as well as mice injected with 10⁶ tumor cells i.p. 2 hr after the last ³H-TdR injection. Animals were sacrificed at intervals up to 6 days. Granulocyte labeling in the blood as well as peritoneal space was near 100% in both groups of animals at all the intervals. Temporal changes in the labeling of lymphocytes (from 10% at 0 day to 22% at day 6), and monocytes (from 20% at 0 day to 57% at day 6) were identical in the blood and peritoneal space of normal animals, indicating a free exchange of cells between these compartments. Higher labeling indices than those in the controls were attained in the blood of tumor-bearing hosts (viz 40% for lymphocytes and 80% for monocytes at 6 days) suggesting an increased turnover of these cells in the circulation. In addition, peritoneal mononuclear cells of tumor-bearing mice showed even a higher labeling than those in the blood (viz 65% for lymphocytes and 92% for monocytes at 6 days) indicating a selective migration and/or retention of newly formed cells within the tumor, in contrast to a random migration into the normal peritoneal cavity. Furthermore, an identical labeling of macrophages to that of monocytes within the tumor indicated a short monocyte-macrophage transition. The preferential accumulation of young mononuclear cells into the tumor may be of functional importance.     

Biotransformation of 3-methoxy-8,14-seco-1,3,5(10),9(11) estratetraen-14,17-dione (secodione) to its 17beta-hydroxy derivative (secol) using immobilized yeast cells (Pichia farinosa Y-118)

The yeast cells of Pichia farinosa Y-118 were immobilized in polyacrylamide gel and used for 17 beta-oxidoreduction of secondione to secol. The loss of hydroxysteroid oxidoreductase activity of cells was found to be insignificant during immobilization. The preparation exhibited greater temperature stability as compared to free cells. The ratio of reaction volume to the volume of immobilized biocatalyst in the range 1.4-1.9 was found to be satisfactory for the reaction conditions studied. This ratio played a significant role in the stability of the catalyst particle, since beyond a critical value the disintegration of gel granules was rapid resulting in sharp decline of activity. The immobilized cell preparation could be used 50 times over a period of 100 days without loss of activity. However, the activity declined in further reuses, leaving the preparation 50 and 35% active after its 60th and 70th uses, respectively.     

On the role of the sterol hydroxyl group in membranes.

The adequacy of sterol derivatives containing a blocked 3-hydroxyl group for sustaining the growth of two sterol auxotrophs has been investigated. Mycoplasma capricolum, a cholesterol-requiring bacterium, grows nearly as well on media supplemented with cholesteryl methyl ether or cholesteryl acetate as on free cholesterol. The two derivatives are recovered unchanged from the bacterial cells. Similarly, cholesteryl methyl ether or ergosteryl methyl ether replace cholesterol or ergosterol as sterol sources for a yeast mutant, strain GL7, defective in 2,3-oxidosqualene-lanosterol cyclization. During aerobic or semianaerobic growth, yeast cells demethylate some of the cholesteryl methyl ether to free cholesterol. However, cells growing on cholesterol methyl ether under strict anaerobic conditions do not produce free sterol. The bearing of these results on the postulated requirement of a free sterol hydroxyl group for membrane function is discussed. Sterol esterification does not appear to be essential for the two microbial systems.