Acid Tea Research Articles

Acidophilic and acid-tolerant actinomycetes in an acid tea field soil.

Acidophilic and acid-tolerant actinomycetes in an acid tea field soil.

Isolation and Characteristics of Acid- and Aluminum-tolerant Bacterium

A screening was attempted to isolate microorganisms that tolerate high concentrations of H+ and ionic aluminum in acidic soils. A new microorganism that can grow in the presence of a high concentration of Al3+ at low pH was isolated from acidic tea fields. The microorganism, designated strain ST-3991, has been identified as a Flavobacterium sp. It can tolerate aluminum concentrations up to 2000 ppm at pH 3.5. The bacterial growth was affected by the concentration of ionic aluminum. When the bacterium was incubated at an initial pH 3.3 in liquid medium containing 100 ppm aluminum, the pH of the medium increased steeply with time, and the medium reached pH 4.4 after 10 days. The bacterium is considered to be useful to improve acidified soils by decreasing the ionic aluminum concentration, while preserving indigenous terrestrial ecosystems.

Microbial biomass and some biochemical characteristics of a strongly acid tea field soil

Abstract Microbial and biochemical characteristics of a strongly acid tea field soil were examined by comparing them with those of other soils of similar type (Andosol) but with different pH values and management conditions. The results of the plate count showed that the numbers of bacteria and actinomycetes in the tea field soil were smaller than those in the cultivated soil with neutral pH. There was a relative abundance of acidophilic or acid-tolerant actinomycetes in the tea field soil. In spite of the low pH, the tea field soil contained larger amount of biomass C and ATP than the cultivated soil with neutral pH. Biomass C/ATP ratio of the tea field soils was smaller than that reported by Ocio and Brookes, due to either a lower content of extractable carbon or higher content of ATP in the soil microbial biomass. Cycloheximide suppressed the CO2 release from the tea field soil amended with glucose by 20% for 3 to 6 h, and 45% for 7 to 24 h of Incubation time, while streptomycin had no effect. Fifty-four % of the activity remained in the soil amended with both antibiotics, suggesting the participation of fungi in the decomposition of glucose as well as that of microorganisms tolerant to both antibiotics. The cultivated soil with neutral pH differed from the tea field soil in the strong suppression of CO2 release by streptomycin. These results, together with the discrepancy between the plate counts and the content of ATP or biomass C, indicated that the microioral characteristics of the acid tea field soil were qualitatively different from those of the cultivated soil with neutral pH. As vanillin is considered to be a model compound for lignin decomposition, the pattern of vanillin decomposition was compared among the tea field soil, the cultivated soil with neutral pH, and a forest soil. The tea field soil decomposed vanillin rapidly, while the decomposition in the cultivated soil with neutral pH was slower. The pattern In the forest soil was similar to that of the tea field soil.

Autotrophic nitrification in acid tea soils

Abstract Investigations to analyze the nature of nitrification in acid soils were carried out in the laboratory using 2 soil types from a tea field. The optimum temperature for the nitrification activity in these soils was 25°C and the activity was inhibited above 35°C, suggesting that the nitrifying bacteria became adapted to the soil conditions. The optimum NH4 +-N concentrations for nitrification ranged between 20 and 200 mg N/100 g of soil and the activity decreased at a concentration above 300 mg N. The effect of acidity on nitrification was studied by using soil samples amended with various amounts of CaCO3. Although the pattern of NO2¯ production changed, the rate of ammonia oxidation was not influenced by the addition of CaCO3. The nitrification activity was completely inhibited by the addition of nitrapyrin or acetylene. These results suggest that acid-tolerant or acidophilic autotrophic nitrification occurs in acid tea soils in Japan.

The lowest limit of pH for nitrification in tea soil and isolation of an acidophilic ammonia oxidizing bacterium

Abstract Investigation to determine the lowest limit of soil pH for nitrification were carried out in the laboratory using acid tea soils with pH range of 3.3 to 5.1. A significant linear correlation was observed between the soil pH value and nitrification rate which was measured by the soil incubation method. It was indicated that the lowest limit of the pH for nitrification was around pH 2.9. Two types of morphologically distinct strains of chemoautotrophic ammonia-oxidizing bacteria were isolated from four tested soils. One of them which was acidophilic was found to grow in a pH range from 3.5 to 7.0 in pure culture. The optimum pH for growth and ammonia oxidation of the acidophilic strain was pH 5.0. Acidophilic ammonia-oxidizing bacteria presumably play an important role in nitrification in acid tea soils.

Effects of difference in fertilization treatments on nitrification activity in tea soils

Abstract It is generally recognized that the nitrification activity in acid soils is very low. Indeed, nitrification in mineral soils has been found to be negligible at pH values below 5.0 (Dancer et al. 1973; Nyborg and Hoyt 1978). However, it was reported that autotrophic nitrification occurred in some tea soils at pH levels far below 5.0 (Walker and Wickramasinghe 1979; Hayatsu and Kosuge 1993). An acidophilic ammonia-oxidizing bacterium has been recently isolated from strongly acidic tea soils in Japan (Hayatsu 1993). On the other hand, fertilization has-been considered to be an important factor influencing nitrification in agricultural soils. For example, several studies have shown that the addition of ammoniacal fertilizer to soils can lead to the increase of the populations of Nitrosomonas (McLaren 1971; Ardakani et al. 1974). Liming of acidic soils also tends to stimulate the nitrification activity (Dancer et al. 1973; Nyborg and Hoyt 1978). Although nitrification has been studied in a wide variet...

Nitrification in acid tea soils and a neutral grassland soil: Effects of nitrification inhibitors and inorganic salts

Nitrification was much slower in five strongly acid (pH 4.0–4.3) soils from tea plantations in Sri Lanka than in a near-neutral grassland soil from the U.K., suggesting that the nitrifiers in these tea soils are close to the lower limit of their pH range. Nitrapyrin effectively inhibited nitrification in all the soils: dicyandiamide was less effective. Low concentrations of KC1 slowed nitrification in the acid tea soils but not in the near-neutral grassland soil. The concentrations of KC1 used (up to 20 mM) were sufficient to cause measurable decreases in soil pH in both acid and neutral soils. It is proposed that this salt-induced decrease in pH is detrimental to nitrifying organisms operating at the limit of their pH range but not to nitrifiers nearer their pH optimum.

Urea hydrolysis in some tea soils

The rate of conversion of urea to ammonium was studied in some acid tea soils of Sri Lanka. The stable levels of urease present in these soils are adequate to hydrolyse the applied urea. There was rapid and almost complete conversion of urea to ammonium and the rate of hydrolysis was independent of soil moisture at 25 per cent and above. The rate of conversion of urea to ammonium depended on the soil polyphenol concentration and had no relationship with either the organic carbon content or the texture.

Nitrification and autotrophic nitrifying bacteria in acid tea soils

Pure cultures of ammonium-oxidizing, autotrophic, nitrifying bacteria were isolated from acid soils (pH range, 4.0–4.5) from tea estates in Sri Lanka (8 soils) and Bangladesh (4 soils). All the Bangladesh nitrifiers were Nitrosospira spp but the Sri Lanka isolates were identified as Nitrosolobus spp Nitrosospira spp and one species of Nitrosovibrio. Nitrite-oxidizing nitrifiers were detected in several of the soils but pure cultures were not isolated. Evidence was obtained that Nitrosospira caused nitrification in situ in an acid soil (pH 4.1). Indigenous nitrate was first eliminated from the soil by denitrification. The soil was then incubated aerobically and the nitrate formed was estimated as N 2O by gas chromatography after denitrification.

Autotrophic Nitrifying Bacteria in Acid Tea Soils from Bangladesh and Sri Lanka

Autotrophic ammonia‐oxidizing bacteria were detected in some Bangladesh and Sri Lanka tea soils and in three other Bangladesh soils. Numbers ranged from 25 to 5500 organisms/g dry soil. Pure cultures were obtained from all the soils either by picking colonies from silica gel plates used for counts or by enrichment culture procedures. The isolates were identified as species of Nitrosolobus, Nitrosomonas and a new species of Nitrosospira.

Effect of gamma irradiation of an acid tea soil from East Pakistan on nitrogen mineralization and nitrification during subsequent incubation

Ammonium- and nitrate-N levels were determined after 13 weeks of incubation (30°C, 80% maximum water-holding capacity) of a ‘tea soil’ (pH 4.2) which had been subjected to varying doses of gamma irradiation (0.05 to 2.00 Mrad) just before incubation. The extent of accumulation of mineral-N (NH4-N+NO3-N) during incubation was little affected by any dose of gamma irradiation. Nitrate accumulation during incubation was not affected by 0.05 Mrad but decreased with increasing dose and was completely inhibited by doses of 0.5 Mrad or higher. The results are discussed in relation to the possible occurrence of heterotrophic nitrification in the acid tea soil.