scholarly journals Short-period fluctuations in the numbers of bacterial cells in soil

1936 ◽  
Vol 119 (814) ◽  
pp. 269-295 ◽  
Keyword(s):  
Room Temperature ◽  
Short Interval ◽  
Bacterial Cells ◽  
Intensive Study ◽  
Natural Conditions ◽  
Short Period ◽  
Initial Decrease ◽  
Plate Counts ◽  
Micro Organisms ◽  
Different Parts

Seasonal changes in the numbers of micro-organisms in fresh soil were first reported at the beginning of the present century; their existence has since been confirmed by workers in many different parts of the world. (For references, see below .) More recently, short-period fluctuations in bacterial numbers were found to exist. Such fluctuations were found in plate counts from daily samples of field soil by Cutler, Crump, and Sandon (1922) and from 2-hourly samples by Thornton and Gray (1930). Periodic determinations of bacterial numbers in soils other than those taken from natural conditions have been few in number and have usually been made as checks on work of some other nature. In earlier work of Russell and Hutchinson (1909), soil incubated at room temperature showed fluctuations in microbial content over such a short interval as 8 hours and over as long a period as 60 days. In their later work, Russell and Hutchinson (1913) working with three soils of different moisture contents, dry, moist, and saturated, incubated at constant temperature, found changes in numbers between samples taken at from 5- to 8-day intervals. Such changes in numbers were not related to temperature, nor necessarily to moisture changes. A more intensive study was made by Allison (1917). He brought soil samples into the laboratory and made bacterial and fungal counts at short intervals of time. Samples taken during the winter showed a drop in numbers of as much as 40% during the first 1½ hours’ storage, followed by a large rise after some hours; in summer the initial decrease was less pronounced, this being attributed to the fact that at that season outdoor temperatures more nearly approached indoor temperatures. Cutler and Dixon (1927) found that, with soil stored at laboratory temperatures in deep narrow bottles, bacterial numbers decreased steadily over a period of 5 weeks. In soil stored in pots with a large surface area, fluctuations in bacterial numbers of as much as 100% were obtained from week to week, and the soil in general behaved as fresh soil.

Electrochemical communication between microbial cells and electrodes via osmium redox systems

2012 ◽  
Vol 40 (6) ◽  
pp. 1330-1335 ◽  
Author(s):  
Kamrul Hasan ◽  
Sunil A. Patil ◽  
Dónal Leech ◽  
Cecilia Hägerhäll ◽  
Lo Gorton
Keyword(s):  
Electron Transfer ◽  
Biofuel Cells ◽  
Major Group ◽  
Electrochemical Biosensors ◽  
Bioelectrochemical Systems ◽  
Bacterial Cells ◽  
Redox Systems ◽  
Microbial Cells ◽  
Fundamental Part ◽  
Micro Organisms

Electrochemical communication between micro-organisms and electrodes is the integral and fundamental part of BESs (bioelectrochemical systems). The immobilization of bacterial cells on the electrode and ensuring efficient electron transfer to the electrode via a mediator are decisive features of mediated electrochemical biosensors. Notably, mediator-based systems are essential to extract electrons from the non-exoelectrogens, a major group of microbes in Nature. The advantage of using polymeric mediators over diffusible mediators led to the design of osmium redox polymers. Their successful use in enzyme-based biosensors and BFCs (biofuel cells) paved the way for exploring their use in microbial BESs. The present mini-review focuses on osmium-bound redox systems used to date in microbial BESs and their role in shuttling electrons from viable microbial cells to electrodes.

scholarly journals DATA ON THE DEVELOPMENT OF HETERAKIS PAPILLOSA IN THE FOWL

1921 ◽  
Vol 34 (3) ◽  
pp. 259-270 ◽  
Author(s):  
H. W. Graybill
Keyword(s):  
Small Intestine ◽  
Salt Solution ◽  
Final Stage ◽  
Minimum Temperature ◽  
Growth And Development ◽  
Room Temperature ◽  
Freezing Temperature ◽  
Physiological Salt Solution ◽  
Natural Conditions ◽  
Short Intervals

In observations on the development of the ova of Heterakis papillosa in cultures, it was found that they failed to develop at a temperature ranging from 2.5–8°C., but developed slowly at a temperature of 11.5–13.5°C. The minimum temperature for development seems to lie between 8° and 11.5–13.5°C. At temperatures ranging in various cultures from 18–29°C. ova developed to their final stage in 7 to 12 days. Undeveloped ova subjected to a freezing temperature for a period of 4 days were viable at the end of that time. Fully developed ones remained alive when exposed out of doors for a period of 7 days at a temperature ranging from 5–62°F. Undeveloped ova survived desiccation at room temperature for a period of 16 days, but not for 41 days. Fully developed eggs were alive after desiccation for 18 days, but not after 49 days. In another instance they were no longer viable after 10 days. Embryos within ova kept in physiological salt solution at room temperature survived during a period of a little over 12 months. Fully developed ova kept in soil outdoors under circumstances approaching natural conditions contained living embryos after a period of 8 months. From a study of a series of artificially infested chickens killed at short intervals it appears that the ova of Heterakis hatch in the small intestine and the larvæ pass by way of the small and large intestines to the ceca where they undergo development to maturity. Larvæ found in the mucosa of the ceca were not in an encysted condition. Feeding of numerous artificially incubated ova may lead to a light infestation, the cause of which has not been definitely determined. A period of 57 days was required for larvæ to reach maturity in a host. The entire cycle from egg to adult requires a minimum time of about 64 days. A brief study of the growth and development of larvæ within the host has been made. No evidence was found of a migration through the tissues. A few penetrate into the mucosa of the ceca.

Hydrothermal Generation of 3-Dimensional WO3 Nanocubes, Nanobars and Nanobricks, Their Antimicrobial and Anticancer Properties

2021 ◽  
Vol 21 (10) ◽  
pp. 5337-5343
Author(s):  
Nilam Qureshi ◽  
Seungjae Lee ◽  
Ravindra Chaudhari ◽  
Pramod Mane ◽  
Jayant Pawar ◽  
...  
Keyword(s):  
Chemical Characterization ◽  
Growth Curves ◽  
Viable Cell ◽  
Inhibition Zone ◽  
Bacterial Cells ◽  
Hydrothermal Route ◽  
3 Dimensional ◽  
Anticancer Properties ◽  
Bacteria And Fungi ◽  
Micro Organisms

In our current endeavor, 3-dimensional (3D) tungsten oxide (WO3) nanostructures (nanocubes, nanobars and nanobricks) have been swiftly generated via hydrothermal route at 160 °C for 24 h. Physico-chemical characterization of the resultant powder revealed formation of WO3 nanostructures with predominantly faceted cube, brick and rectangular bar-like morphology. The present study was also aimed at exploring the antimicrobial and anticancer potential of WO3 nanostructures. Antimicrobial activity was tested against different micro-organisms viz., Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli and Aspergillus fumigatus. The antibacterial and antifungal activity was ascertained against these micro-organisms by measuring the diameter of inhibition zone in agar well diffusion test which revealed that the resultant WO3 nanostructures acted as excellent antibacterial agents against both bacteria and fungi but were more effective against the fungus, A. fumigatus. To examine the growth curves of bacterial cells, time kill assay was monitored for E. coli, against which significant antibacterial action of WO3 nanostructures was noted. The anti-cancer activity of WO3 nanostructures was found to be concentration-dependent against KB cell line by viable cell count method. In our pilot study, WO3 nanostructures suspension with concentration in the range of 10−1 to 10−5 mg/ml was found to kill KB cells effectively.

Sausage Casings as a Model for Attachment of Salmonella to Meat

1993 ◽  
Vol 56 (5) ◽  
pp. 390-394 ◽  
Author(s):  
ISABEL WALLS ◽  
PETER H. COOKE ◽  
ROBERT C. BENEDICT ◽  
ROBERT L. BUCHANAN
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Bacterial Attachment ◽  
Bacterial Cells ◽  
Inoculum Level ◽  
Plate Counts ◽  
Increasing Temperature ◽  
Convenient Model ◽  
Sausage Casing ◽  
Scanning Electron

Artificial sausage casings were used as a model for studying bacterial attachment to meat connective tissue. Sausage casings of known mass were exposed to suspensions of Salmonella typhimurium in 0.15 M NaCl under various time, temperature, and inoculum level regimes, then washed to remove unattached bacteria. Attached bacterial cells were enumerated using both plate counts and scanning electron microscopy. Bacterial cells attached to sausage casing surfaces within 1 min of incubation. Numbers of attached cells increased with increasing temperature and inoculum levels and with time. Rates of attachment of S. typhimurium to sausage casings were comparable with those reported for attachment to meat surfaces. Sausage casings appear to be a convenient model for examining mechanisms of bacterial attachment to meats.

InAs Quantum Dots in AlAs/GaAs Short Period Superlattices: Structure, Optical Characteristics and Laser Diodes

2001 ◽  
Vol 707 ◽  
Author(s):  
Vadim Tokranov ◽  
M. Yakimov ◽  
A. Katsnelson ◽  
K. Dovidenko ◽  
R. Todt ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Room Temperature ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Inas Quantum Dots ◽  
Transmission Electron ◽  
Short Period ◽  
Short Period Superlattices ◽  
Emitting Lasers ◽  
Cladding Layers

ABSTRACTThe influence of two monolayer - thick AlAs under- and overlayers on the formation and properties of self-assembled InAs quantum dots (QDs) has been studied using transmission electron microscopy (TEM) and photoluminescence (PL). Single sheets of InAs QDs were grown inside a 2ML/8ML AlAs/GaAs short-period superlattice with various combinations of under- and overlayers. It was found that 2.4ML InAs QDs with GaAs underlayer and 2ML AlAs overlayer exhibited the lowest QD surface density of 4.2x1010 cm-2 and the largest QD lateral size of about 19 nm as compared to the other combinations of cladding layers. This InAs QD ensemble has also shown the highest room temperature PL intensity with a peak at 1210 nm and the narrowest linewidth, 34 meV. Fabricated edge-emitting lasers using triple layers of InAs QDs with AlAs overlayer demonstrated 120 A/cm2 threshold current density and 1230 nm emission wavelength at room temperature. Excited state QD lasers have shown high thermal stability of threshold current up to 130°C.

scholarly journals Growth of Micro-organisms in Two Propofol Products at Room Temperature

2005 ◽  
Vol 25 (2) ◽  
pp. 154-161
Author(s):  
Michiaki YAMAKAGE ◽  
Hiroki YAMAMOTO ◽  
Akiyoshi NAMIKI
Keyword(s):  
Room Temperature ◽  
Micro Organisms

Effect of Storage and Consumer Handling on Staphylococcal Counts of Dried Beef and Dried Fish

1984 ◽  
Vol 47 (5) ◽  
pp. 352-353 ◽  
Author(s):  
A. A. ADESIYUN
Keyword(s):  
Room Temperature ◽  
Health Hazard ◽  
Storage Period ◽  
Colony Forming Units ◽  
Plate Counts ◽  
The Mean ◽  
Dried Fish

Changes in staphylococcal counts of dried beef and dried fish during storage and while exposed to prospective buyers in a Nigerian market were investigated. The mean staphylococcal counts in dried beef and dried fish were 9.9 × 105 and 4.6 × 106 colony-forming units (CFU)/g and the mean aerobic plate counts were 2.0 × 107 and 1.2 × 108 CFU/g, respectively. Over a 28-d storage period at room temperature, the mean staphylococcal count declined about 100-fold for both products, i.e., from 9.9 × 105 to 3.0 × 103 CFU/g in dried beef and 4.6 × 106 to 2.2 × 104 CFU/g in dried fish. The decline in aerobic plate counts were from 2.0 × 107 to 6.5 × 104 CFU/g for dried beef and 1.2 × 108 to 1.4 × 105 CFU/g for dried fish, about a 1000-fold decline. Market samples of both products, though from the same batch but exposed to handling by prospective buyers, consistently showed higher staphylococcal contamination over the study period. Consumption of these products repeatedly exposed to human handling in the market for long periods may be a health hazard, particularly those that are ready-to-eat.

A technique for the study of oxygen availability to micro-organisms in soil and its possible use as an index of soil aeration

1947 ◽  
Vol 37 (3) ◽  
pp. 249-256 ◽  
Author(s):  
D. M. Webley
Keyword(s):  
Oxygen Uptake ◽  
Oxygen Availability ◽  
Bacterial Cells ◽  
Experimental Conditions ◽  
Soil Aeration ◽  
Resultant Effect ◽  
Aeration Conditions ◽  
A New Technique ◽  
Micro Organisms ◽  
Properties Of Soil

1. In Part I of the paper details are presented of a new technique for the study of oxygen availability to bacteria added to soil. In essentials the technique consists of adding a washed suspension of bacterial cells together with excess of suitable oxidizable substrate to air dried, sieved soil contained in Warburg vessels. The rate of oxygen uptake is looked upon as a function of the aeration conditions within the soil. The results can be expressed by means of a conventional figure called the aeration factor (or A.F.).2. In Part II with the use of the technique it has been shown that two physical properties of soil which influence oxygen availability under the experimental conditions of the technique are (a) moisture content of the soil, (b) the amount of break-up of the soil crumbs. Since the A.F. measures the resultant effect produced by these factors it may be regarded as an index of soil aeration.

The Annual Rhythm of Activity of the Lateral Meristems (Cambium and Phellogen) in Pinus Halepensis Mill. and Pinus Pinea L.

IAWA Journal ◽  
1984 ◽  
Vol 5 (4) ◽  
pp. 263-274 ◽  
Author(s):  
Nili Liphschitz ◽  
S. Lev-Yadun ◽  
E. Rosen ◽  
Y. Waisel
Keyword(s):  
Mediterranean Climate ◽  
Pinus Halepensis ◽  
Rest Period ◽  
Pinus Pinea ◽  
Winter Dormancy ◽  
Natural Conditions ◽  
Quiescent Period ◽  
Short Period ◽  
Climate Patterns ◽  
Almost All

The annual rhythms of cambial and phellogen activity in Pinus halepensis and P pinea were investigated. Under natural conditions the cambium of P halepensis begins its activity in autumn, enters a quiescent period during midwinter, resurnes activity towards spring and enters a second rest period in summer. The ring border is formed during summer. Irrigated plants growing outdoors were active almost all the year round.The cambium of P pinea is active between April and November and enters a true winter dormancy.The duration of xylem production exceeded that of the phloem. More xylem than phloem cells were formed. The phellogen was active during a short period only.Pinus halepensis seems to follow the Mediterranean climate patterns whereas P pinea follows the pattern of a colder climate.

Chemical Changes in Nitrite-Treated Atlantic Cod Fillets in Relation to Spoilage Assessment

1956 ◽  
Vol 13 (4) ◽  
pp. 559-567 ◽  
Author(s):  
E. B. Vaisey
Keyword(s):  
Analytical Methods ◽  
Room Temperature ◽  
Atlantic Cod ◽  
Intensive Study ◽  
Chemical Changes

Results are reported from preliminary studies using various analytical methods to detect spoilage in nitrite-treated Atlantic cod. In a more intensive study of one method, it was found that fresh fillets could be separated from spoiling fillets by their gains in tyrosine value after 3-hour incubation at room temperature.

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