ALBERT

Notes: Summary Soil arthrobacters in contrast with coryneform bacteria from cheese surfaces may accumulate large amounts of an intracellular polysaccharide. This accumulation of reserve material leads to a much enlarged cell size. The highest polysaccharide contents were found in nutrient media containing relatively high amounts of glucose and inadequate amounts of nitrogen or phosphorus. Sulphur deficiency and a low pH of the media also favoured accumulation of the reserve material. Investigation of the structure of the isolated polysaccharide by the methylation technique, the periodate method and β-amylolysis showed that it was a glycogen with an exceptionally high degree of branching $$(\overline {CL} 7 - 9,\overline { ECL} 4 - 5 and \overline {ICL} 2 - 3 {\text{of glucose units)}}$$ . This structure is very similar to that of glycogen phosphorylase limit dextrin. Of the various enzymes required for the synthesis and breakdown of glycogen the debranching enzyme was found to be absent from cell-free extracts of soil arthrobacters. This suggests that in vivo the poor activity of this enzyme is responsible for the accumulation of a divergent type of glycogen viz. glycogen phosphorylase limit dextrin. Nitrogen deficiency promotes polysaccharide accumulation by increasing the supply of glucose-1-phosphate, the essential precursor of glycogen.

Notes: Abstract Thirty-fourSphaerotilus andLeptothrix strains were isolated from sewage, activated sludge and iron-containing ditch- and well-water, and their morphological and physiological characters studied. The organisms were grown under different conditions, e.g. on peptoneglucose agar and yeast-extract-manganous-carbonate agar, and in running ditch-water containing ferrous iron. Growth of these bacteria in synthetic media, with glucose as carbon source and aspartic and glutamic acids or inorganic nitrogen compounds as nitrogen source, required added vitamin B12 unless nitrogen was supplied as hydrolyzed casein or as a mixture ofl-amino acids. Methionine was found to be responsible for this replacement of vitamin B12. Five different types of sheath-forming bacteria were distinguished in the present study. Type I is the typical sewage organismSphaerotilus natans. It has large cells, grows well with relatively high concentrations of organic substrates, but cannot oxidize manganous compounds. In running ditch-water containing ferrous iron, ferric hydroxide may be deposited in and on its sheaths. AlthoughS. natans under such conditions may resemble the iron bacteriumLeptothrix ochracea, it has relatively long sheaths, partly filled with cells in contrast with the short and mostly empty sheaths of the latter.S. natans could be readily reisolated from its iron-bacterium cultures but very seldom from crude cultures ofL. ochracea; thus the two organisms are clearly different. Types II and III have relatively large cells, respond poorly to organic nutrients, but are able to oxidize manganous compounds. Type II forms fungus-like flocks in liquid media and resembles microscopicallyL. lopholea, with which it may be identical. Type III resemblesL. ochracea more closely than does any other type, but is probably not identical with it; the nameL. pseudo-ochracea sp.n. is proposed for this type. Type IV is intermediate between types I and V. In media with relatively high concentrations of organic nutrients it behaves like a sewage organism, but in poor media containing ferrous and manganous compounds, it behaves like an iron bacterium, depositing large amounts of ferric and manganic oxides in and on its sheaths; for this type the nameL. cholodnii sp.n. is proposed. Type V has small cells, grows poorly in all media tested, but actively oxidizes manganous compounds; the nameLeptothrix discophora is reserved for this type. The globular inclusions in the cells ofS. natans and other members of theSphaerotilus-Leptothrix group consist of poly-β-hydroxybutyrate.

Notes: Summary A description is given of some microbiological tests for the determination of plant-available copper, magnesium and molybdenum in soils. In these investigationsAspergillus niger and in a few casesAzotobacter chroococcum andBact prodigiosum were used. From the figures obtained it is revealed that soils on which the plants are suffering from the so-called “reclamation disease”, have a much lower available copper content than those producing healthy crops. Soils on which the plants show the so-called “Hooghalen disease”, have a very low content of available magnesium. From these results and from experiments with cereals it is concluded that the “reclamation disease” is caused by a deficiency of plant-available copper and that a deficiency of available magnesium is the chief cause of the “Hooghalen disease”.