Allogibberic acid: An inhibitor of flowering in Lemna perpusilla

Allogibberic acid (I) has been identified as the compound responsible for the inhibition of flowering, increase in frond multiplication rate and decrease in frond size produced in Lemna perpusilla 6746 by autoclaved, unbuffered aqueous solutions of gibberellic acid (VII). 13-Deoxyallogibberic acid (IV), a product of autoclaving aq. GA₇ (VIII) solutions, also inhibits flowering in L. perpusilla and is about 10 times more active than allogibberic acid.     

Changes in heated and autoclaved forest soils of S.E. Australia. I. Carbon and nitrogen

The effect of heating and autoclaving on extractable nitrogen, N mineralisation and C metabolism was studied by heating five forest soils in the laboratory, simulating the range of effects of heat due to bushfire. Top soil (0–5 cm) was heated to 60 °C, 120 °C and 250 °C for 30 minutes; unheated soil was taken as a control. Samples of the soil heated to 250 °C were also inoculated with fresh soil to accelerate the recovery of the microbial population. Soil autoclaving was carried out as another heat treatment (moist heat). Soils were analysed immediately after heating and 3 times during seven months of incubation to assess immediate and longer-term effects of heating.Extractable N (organic and mineral forms) increased after heating to 120 °C, but decreased with further heating to 250 °C suggesting the volatilisation of N. N associated with microbial biomass diminished with heating and was barely detectable after the 250 °C treatment. Microbial biomass was an important source of soluble N in heated soils, and only partly recovered during subsequent long incubation. The amount of N mineralised during incubation depended on both soil and temperature. Nitrification did not occur when soils were heated to 250 °C (with or without inoculum), or after autoclaving, demonstrating the high sensitivity of nitrifiers to heat. At the beginning of soil incubation, respiration was enhanced in heated soils (250 °C, 250 °C inoculated) and autoclaved soils, but after 30 days of incubation respiration decreased to values either similar to or lower than those in control. This respiration pattern indicated that a fraction of labile C was released by heating, which was quickly mineralised within 30 days of incubation. These results demonstrate some effects of soil heating on C and N dynamics in forest soils.     

Effects of autoclave-induced carbohydrate hydrolysis on the growth ofBeta vulgaris cells in suspension

Media of de Greef & Jacobs (1979) were autoclaved either with all the nutrient components in a single vessel (medium 1) or with the following components in separate vessels: FeNa–EDTA+CaCl₂ (medium 2), FeNa–EDTA+NaH₂PO₄ (medium 3) or sucrose (medium 4). Medium 5 was prepared by autoclaving FeNa–EDTA+NaH₂PO₄ and sucrose in two separate vessels. It was found that the dry mass yield of cell suspensions ofBeta vulgaris was lowest in medium 1, followed by media 2 and 3. There was no significant difference among media 3, 4, and 5.The plot of dry mass yield of the cell suspensions against the rates of cyanide-initiated oxygen consumption which indicate the extent of carbohydrate hydrolysis of the media during autoclaving, indicated the presence of a threshold rate of about 17–20 nmol ml^–1 min^–1. Dry mass yield of the suspensions decreased rapidly when the rate exceeded this value.For media with glucose as the source of carbohydrate, the rate of cyanide-initiated oxygen consumption exceeded the threshold value by a factor of 1.5 to 2, depending on the volume of the media autoclaved.Abbreviations FeNa-EDTA ferric monosodium ethylenediamine-tetraacetic acid     

Decomposition of aqueous solutions of gibberellic acid on autoclaving

A qualitative and quantitative analysis of the decomposition of unbuffered and buffered (pH 3–8) aqueous solutions of gibberellic acid (GA₃) on autoclaving is recorded. The identified products, which vary in composition with pH, are iso-GA₃ (II), iso-GA₃ hydroxy acid (III), gibberellenic acid (IV), allogibberic acid (V), epiallogibbe detected after autoclaving in all cases. The identified products, in all cases, account for not less than 95% of the decomposition product, Dehydroallogibberic acid has not previously been recorded as an aqueous decomposition product of GA₃ and its biological activity in the lettuce hypocotyl test is recorded.     

Effect of activated charcoal, autoclaving and culture media on sucrose hydrolysis

The effect of activated charcoal, autoclaving and culture media on sucrose hydrolysis in tissue culture media was investigated. Activated charcoal acidified an aqueous sucrose (5%) solution and culture media by about 1 to 2 units after autoclaving. Sucrose hydrolysis in tissue culture media and/or aqueous sucrose (5%) solutions containing activated charcoal (buffered to pH 5.8) was dependent on both the hydrogen ion concentration (pH) and autoclaving. After autoclaving, 70%, 56% and 53% sucrose hydrolysis were respectively recorded in a 5% sucrose solution, Murashige and Skoog (MS) and Gamborg B5 (B5) liquid media in the presence of 1% activated charcoal, added before autoclaving. In the absence of activated charcoal, autoclaving resulted in about 20% of the sucrose being hydrolyzed.     

The effect of Ptilotus plant tissue on pH of in vitro media

Changes occur in the pH of in vitro nutrient media during preparation and over the culture period. The direction and extent of the changes depend upon the initial pH and the presence or type of gelling agent. Agar-based medium was progressively acidified in the presence of a living Ptilotus exaltatus explant. This was not a response to wounding and the rate of acidification could be maintained by frequent replacement of the medium. The rate appears to be pH dependent with an equilibrium occurring at pH4. The pH effect was not accounted for by K⁺ uptake.     

Changes in heated and autoclaved forest soils of S.E. Australia. II. Phosphorus and phosphatase activity

The effect of soil heat and autoclaving on labile inorganic P (Bray I), microbial P (P-flush) and on phosphatase activity was studied by heating five forest soils in the laboratory, which simulated the effects of heat during bushfires. Top soil was heated to 60 °C, 120 °C and 250 °C or autoclaved for 30 minutes. Soils were analysed immediately after heating and during seven months of incubation to assess immediate and longer-term effects of heating.Labile inorganic P increased immediately after heating and autoclaving soils, with the highest amount recorded for the 250 °C treatment. Phosphorus associated with microbial biomass decreased with heat, and none or small amounts were detected in soils heated to 250 °C and autoclaved, because high temperatures killed the microbial population. Most of the P released from microbes acted as a source of labile inorganic P in soils low in inorganic P, and some of the released P was fixed by the soil. In one soil high in inorganic labile P and with undetectable amounts of microbial-P, the increase in Bray P on heating could only be assigned to solubilisation of other sources of total P Because high temperatures denature enzymatic proteins, phosphatase activity diminished with the increase in temperature, and no activity was detected in 250 °C and autoclaved soils.Phosphorus released by heating decreased during incubation in three of the five soils studied, approaching values observed in unheated soils. Simultaneously, an increase in microbial P was observed in these heated soils, indicating that the partial recovery of microbial biomass acted as a sink for the decrease in Bray-P measured. Phosphatase activity recovered only partially during incubation of heated soils.     

Chitinase is an inducible enzyme in Beauveria bassiana

Sterilization of chitin by autoclaving or boiling causes release of d-glucosamine and N-acetylglucosamine from the macromolecule and these solubilized components actually function as the inducers for synthesis of chitinase. The insoluble macromolecule is not an inducer of chitinase since sterilization by dry heat or chloroform will not bring about release of the amino sugars or induction of the enzyme. Free glucosamine, N-acetylglucosamine, and chitobiose are all good inducers of chitinase. Most sustained synthesis of the enzyme occurs in an autoclaved chitin-salts medium.     

Evaluation of velvet bean meal as an alternative protein ingredient for poultry feed

The effect of certain simple and cost-effective processing methods on the nutritional and anti-nutritional properties of seed materials of an under-utilized food legume, Mucuna pruriens (L.) DC. var. utilis (Wall. ex Wight) Baker ex Burck (velvet bean, VB), collected from Valanadu, Kerala, India was analyzed in experiment 1. The raw VB seeds were found to contain appreciable levels of crude protein (263.2 g/kg dry matter (DM)); ether extract (79.6 g/kg DM); crude fiber (95.8 g/kg DM) and ash content (38.4 g/kg DM). Among the different treatments used, soaking in sodium bicarbonate solution + autoclaving was more effective in reducing maximum levels of various anti-nutritional compounds of VB seeds. Furthermore, in experiment 2, the effect of inclusion of different levels of velvet bean meal (VBM; subjected to soaking in sodium bicarbonate solution + autoclaving) as an alternative protein source in poultry feed on the growth performance of commercial-type broiler birds was investigated. The results indicate that the inclusion of VBM up to the 40% level exhibited better growth performance of the broiler birds such as feed intake, body weight gain, feed conversion ratio and protein efficiency ratio in both the starter and finisher phases.     

Inactivation of the BSE agent

In the studies carried out so far, the BSE agent has proved to be just as resistant as other TSE agents to inactivation by procedures such as autoclaving or exposure to sodium hydroxide that are effective with conventional microorganisms. However, in common with other TSE agents, the BSE agent appears to be effectively inactivated by exposure to sodium hypochlorite solutions containing high levels of available chlorine. Not surprisingly, the BSE agent has been found to survive at least some of the rendering processes that were used to process tissues discarded by abattoirs in the EU during the early 1980s. Despite the survival of BSE infectivity after autoclaving or exposure to sodium hydroxide, it is known that combining these procedures results in a very reliable degree of inactivation for TSE agents generally. The combination of heat and alkali has also been shown to be effective with a mouse-passaged strain of BSE agent, even at a temperature of only 100 degrees C for a minute. Also, in carrying out BSE-spiked validation studies relating to the safety of bone-derived gelatin, it has also been found that the exposure of acid-treated bone (which is free from any obvious remains of fatty or proteinaceous tissue) to 0.3 M sodium hydroxide for two hours knocks out any residual BSE infectivity.