Lester Hankin

The Use of Solid Media for Detection of Enzyme Production by Fungi

SUMMARYSolid media are described on which the production of the extracellular enzymes amylase, lipase, DNA- and RNAase, pectinase, protease, urease, and chitinase were detected. The media were test...

Solid Media Containing Carboxymethylcellulose to Detect Cx Cellulase Activity of Micro-organisms

Solid media containing carboxymethyl cellulose (CMC) were developed to detect CX cellulose-producing micro-organisms. Hydrolysis of CMC was seen as a clear zone around colonies after flooding plates with 1% aqueous hexadecyltrimethyl-ammonium bromide. Tests with ten bacterial and four fungal species showed that the degree of substitution (DS) of the CMC affects both growth and enzyme production. Most of the organisms produced more CX cellulase on CMC with a DS of 0-9, but CMC with a DS of 0-4 was better for one fungus. A qualitative measure of cellulase production may be obtained by calculating the ratio of zone size to colony diameter. Solid media containing CMC provided a more rapid assay of CX cellulose production than a medium containing native cellulose.

Microorganisms from composting leaves: Ability to produce extracellular degradative enzymes

Mixed populations of bacteria, fungi, and actinomycetes in a leaf compost pile were examined over a 100-day test period for their ability to produce extracellular proteolytic, lipolytic, amylolytic, cellulolytic, pectolytic, and ureolytic enzymes and ability to utilize alkanes. Urea was added to the leaves to adjust the carbon to nitrogen ratio but was of little value in maintaining the proper ratio since it was degraded within the first few days. The degradative enzymes excreted by microorganisms was dependent on the temperature of the pile. In many cases organisms able to produce specific extracellular enzymes at medium temperatures were able to grow at high temperatures, but either did not excrete the specific enzymes or the enzymes were inactivated by the high temperature.

Plant Contamination by PCBs from Amended Soils

Plants accumulated PCBs (Aroclors) from soil amended with lake sediment contaminated with Aroclors 1248, 1254, and 1260. Uptake into different parts of vegetable plants was investigated in the field by growing beets ( Beta vulgaris L .), turnips ( Brassica rapa L .) and beans ( Phaseolus vulgaris L .). In beets and turnips, leaves accumulated larger concentrations of PCBs than the roots. In beans, leaves and pods contained higher concentrations than the stems, while only low concentrations were detected in the seeds. Bioaccumulation of Aroclors by plants was in the following order: Aroclor 1248 > 1254 > 1260. Relative to their concentration in the soil, the lower chlorinated PCB isomers which are more soluble in water and more volatile were more abundant in plants then the higher chlorinated isomers.

Effect of mulches on bacterial populations and enzyme activity in soil and vegetable yields

SummaryMulches in five combinations of clear plastic, black plastic, and undecomposed leaves covered by or on top of black or clear plastic film to modify soil temperature, were used to study the enzyme activity of the soil and numbers of bacteria able to produce degradative enzymes. Yield of pepper and broccoli planted through the mulches was measured.The numbers of bacteria in the soil able to excrete protease, phosphatase, cellulase, and lipase were correlated with one another suggesting that the same group of organisms excreted the different enzymes. The activity of enzymes in the soil was similarly correlated. Bacterial urease-producers and the urease activity in the soil were not correlated with the number of other enzyme producers or activity of other enzymes in soil suggesting an independent population of urease producers degraded the urea fertilizer used. Temperature differences of 11–14°C provided by the various mulches appeared insufficient to create important differences in populations and biochemical activities of soil bacteria.Yield of broccoli was greatest early in the season in soil warmed under black polyethylene plastic and later in the season in the soil cooled with leaf mulch over black plastic. Yield of pepper was greatest in mid-to-late summer on soil warmed with black plastic, but the highest yield was obtained in early fall in soil with clear and black plastic over leaf mulch.

RELATION OF LAND USE TO SOME DEGRADATIVE ENZYMATIC ACTIVITIES OF SOIL BACTERIA

An examination was made of bacterial populations in a number of Connecticut soils and their ability to produce certain degradative enzymes. The soils examined were obtained from cultivated land, pasture, orchard, forest, forest litter, tidal march, and swamp. The biochemical activities of the bacteria generally occurred in the following order of increasing frequency: cellulolytic < pectolytic < amylolytic < lipolytic < proteolytic. The proportion of bacteria able to degrade protein and starch appears to be related to the present use of the soil. The percentage of bacteria in a given soil able to degrade cellulose or pectin was not greatly influenced by the present soil use. The proportion of lipolytic bacteria in soils was exceedingly variable. These results are discussed in relation to source and type of substrate available to the soil bacteria.

Polychlorinated Biphenyls in Food: A Review

Literature published from 1970 through mid-1984 on polychlorinated biphenyl (PCB) contamination of foods, including fish, dairy products, packaged and processed food and human milk, is reviewed. Sources of the contamination are discussed. The reports show that although PCBs are no longer manufactured in this country, large quantities have entered the environment. High concentrations in sediments of some streams and lakes are a continuing source of PCB entry into the food chain via the fish caught in these waters. Accidental leakage and spills from electrical transformers containing PCBs, which are in use, can also be a source of contamination. Other sources of PCB contamination such as silo sealants and packaging materials manufactured from carbonless paper containing PCBs have been essentially eliminated.

Microbial degradation of polychlorinated biphenyls in soil

Removal of PCB-containing sediment (includes Aroclors 1248, 1254, and 1260) from a contaminated pond and placement on land have been suggested to prevent continued pollution of the Housatonic River system in Connecticut. To test if soils differed in their ability to degrade PCBs, we incubated the contaminated pond sediment in shake culture with eight agricultural or forest soils. The rate and degree of degradation of Aroclors 1248, 1254, and 1260 present in the sediment were followed over a 112-d period. All soils but one degraded Aroclor 1248 at least 70% in 14 d and over 90% in 112 d. Aroclor 1254 was degraded by only three soils and a pine litter. The rate of degradation of Aroclor 1254 was much slower than that of Aroclor 1248, and only about 40% of 1254 was degraded in 112 d. Aroclor 1260 was not degraded by any soil sample. As the growth of aerobic organisms in the shake cultures increased, degradation of Aroclor 1248 also increased in parallel. The number of organisms in the shake cultures that were able to use Aroclor 1221 as a carbon source reached a peak at 70 d, indicating a lag of growth of Aroclor-degrading organisms. The use of certain agricultural soils for disposal of PCB-containing sediments may have limitations.

Utilization of cutin by a pseudomonad isolated from soil

SummaryA Pseudomonas sp., which has been isolated from orchard soil, is able to utilize cutin as a sole source of carbon. Products obtained from the culture filtrate corresponded to that obtained by alkaline hydrolysis of cutin.

LEAD POISONING–A DISEASE OF OUR TIME

Lead poisoning among children who eat paint chips and other non-food items containing lead is a serious environmental and public health problem. Ingestion of lead can result in irreversible biological effects including mental retardation and even death. Additionally, ingestion of food and water contaminated with lead, and inspiration of lead-polluted air may also bring about detrimental physiological responses, especially to enzyme systems concerned with blood synthesis. This review discusses the lead poisoning problem among children as regards sources of contamination as well as testing methods used to find potential victims of this man-made disease. The amounts and sources of lead found in foods, both raw and processed, and the quantities found in air are detailed. Implications of daily ingestion of small amounts of lead from food, water, and air are discussed.