Biosynthesis of plant hormones during anaerobic digestion of instant coffee waste

A large amount of solid waste remains after the production of instant coffee. This waste has to be moved to dumps, where it poses a threat of environmental pollution. Treatment of this waste by anaerobic methanogenic thermophilic digestion produced, besides biogas, a digested slurry which was used as a growth medium for horticulture, and proved to be a suitable and economical substitute for peat moss. Biological tests with mung bean cuttings and Grevillea plantlets showed promotional effects on rooting of the slurry and its sieved fraction extract, washed with water (Capul). Green coffee beans, instant coffee waste, its anaerobically-digested slurry and Capul were extracted by various methods and the extracts were analyzed by TLC, HPLC and GC/MS. Examinations showed clearly the presence of IAA and IBA in free and bound forms in all the substrates. The values of free and bound IAA were calculated by use of an internal standard and GC/MS. The amount of conjugated IAA was found to be much higher than that of free IAA, in both the coffee beans and instant coffee waste (11.1 vs 2.7 nmol g^–1, respectively). In the digested slurry and Capul, however, most of the IAA was present as the free form and was approximately 23.5–33.0 nmol g^–1, which is almost ten times more than in the waste, and almost twice the total amount of IAA in coffee beans. It is postulated that the high levels of free IAA in the digested instant coffee waste are a result of catabolism of tryptophan by anaerobic bacteria.     

Heterotrophic glucose uptake and respiration in Lake Kinneret

The turnover times of glucose, averaged for 0–10 m in the upper waters of Lake Kinneret and measured by the addition of single or multiple concentrations of substrate, ranged from 23 to 188 hours and 1 to 87 hours respectively. Potential uptake rates (estimated as V_max) ranged from 0.095 to 1.94 µg glucose l^–1h^–1, while measured uptake rates varied from 0.09 to 1.1 µg glucose l^–1h^–1. Concentrations of dissolved carbohydrates and glucose averaged 0.71 mg glucose equivalents l^–1 and 39 µg glucose l^–1 respectively. No evident relationships between glucose cycling and any fractions of dissolved organic matter, phytoplankton biomass or primary productivity were found. Turnover times were generally most rapid immediately after the decline of the spring Peridinium bloom. The respiration percentage of incorporated glucose ranged from 25% to 61% with highest values during the summer months. Respiration may be influenced by the nature of the indigenous bacterial population as well as by temperature. Daily heterotrophic glucose carbon uptake was about 9% of the photosynthetic incorporation and could provide a bacterial yield of about 7 × 10⁴ ml^–1d^–1.     

Studies on the effect of lucerne saponins on the respiration of cotton seeds using 18O2

The inhibitory effect of lucerne saponin on the respirationof cotton seeds was studied using ¹⁸O₂. Oxygen consumption ofsaponin-treated seeds was 40–60% less than that of water-treatedseeds. Embryos excised immediately after pre-immersion consumedoxygen in a manner similar to that after water or saponin treatment. (Received December 25, 1972; )     

Kinetics of the inhibition of cotton seeds germination by lucerne saponins

The extent of inhibition of cotton-seed germination by lucernesaponins depends upon the period of pre-immersion in the saponinsolution prior to germination. After 5 hr of pre-immersion ina 0.5% lucerne saponin solution, a 40% drop in germination wasnoted. The respiration rate decreased after 3 hr of pre-immersion.The diffusion of oxygen through the membranes of seeds pre-immersedin saponins also decreased with an increasing pre-immersiontime. Inhibition of germination was irreversible after pre-immersionin saponins for 6 hr or more. The effect of saponins does not appear to be biochemically specificbecause the germination and respiration rates of the cottonseeds which were immersed in aqueous solutions of anionic, nonionicor cationic commercial surfactants were similarly inhibited. (Received February 19, 1975; )