Glycogen Metabolism in Aureobasidium Pullulans: A Glycogen Synthetase with Unusual Activation Properties

Abstract

Cultures of filamentous fungi that secrete significant amounts of exopolysaccharides are among the most difficult of fermentation fluids, presenting difficulties in the areas of aeration, agitation, mixing, and control that may in turn impact the physiology of the microorganism in an undesirable manner. The fungus Sclerotium glucanicum, which produces a potentially useful exopolysaccharide known as scleroglucan, illustrates many such difficulties. This review discusses in detail the range of physiological studies on the producing microorganism itself, including those concerning formation of “undesirable” byproducts, principally oxalate, but also, under certain conditions, other TCA cycle acids. In addition, the bioreactor technology in use for production of this type of biopolymer is discussed in relation to the difficulties such fluid types present. The potential of pneumatically agitated reactors for such production is evaluated, and the lack of fundamental studies on such reactors and on the hydrodynamics and mixing behavior of such complex fluids is pointed out.     

Semen cryopreservation in golden‐headed lion tamarin,Leontopithecus chrysomelas

Wild animal genetic resource banking (GRB) represents a valuable tool in conservation breeding programs, particularly in cases involving endangered species such as the golden‐headed lion tamarin (Leontopithecus chrysomelas). Thus, we aimed to assess a sperm freezing protocol for golden‐headed lion tamarins using two different exenders: BotuBOV® (BB) and Test Yolk Buffer® (TYB). Ejaculates were collected by penile vibrostimulation from animals housed at São Paulo Zoological Park Foundation, São Paulo, Brazil, and after immediate analysis, two aliquots were diluted in BB and TYB. Postthawing samples were evaluated for total and progressive motility, plasma membrane and acrosome integrities, mitochondrial activity, susceptibility to oxidative stress, and sperm–egg‐binding. No differences between BB and TYB were found for most seminal parameters, except for acrosome integrity and susceptibility to oxidative stress (in both cases BB showed higher values). However, in spite of these differences and regardless of the extender used, postthaw sperm motility and viability with the described protocol were encouraging (on average >50% and >80%, respectively), indicating that sperm cryopreservation may be a short‐term measure for the conservation of golden‐headed lion tamarins.     

Cyanobacteria passage through drinking water filters during perturbation episodes as a function of cell morphology, coagulant and initial filter loading rate

Eight pilot-scale in-line filtration trials were performed to evaluate the passage of cyanobacterial cells through drinking water filters after sudden increases in hydraulic loading rates. Trials were performed at 30 °C using two coagulant combinations (aluminum sulfate and cationic polymer or ferric chloride and cationic polymer), two initial filter loading rates (7 or 10 m/h) and two species of morphologically different cyanobacteria (Microcystis aeruginosa or Anabaena flos aquae). The filter was perturbed by instantaneously increasing the hydraulic loading rate by 50%. Filter influent and effluent water qualities were characterized by measuring turbidity, particles and chlorophyll a. The observed post-perturbation filter effluent chlorophyll a peaks were 1.6–48 times greater than the pre-perturbation averages. Chlorophyll a peaks were larger for M. aeruginosa than for A. flos aquae. Chlorophyll a peaks were also larger for the higher (10 m/h) than for the lower (7 m/h) initial filter loading rate. The post-perturbation effluent turbidity peaks were 1.4–7.2 times greater than the pre-perturbation averages. The post-perturbation effluent particle peaks were 6.5–25 times greater than the pre-perturbation averages. These results indicate that particles were a more sensitive indicator of cyanobacterial passage than turbidity.     

Hyperthermic treatment of chromomycosis with disposable chemical pocket warmers

A case of chromomycosis in which hyperthermia proved effective is reported. The patient was a 56-year-old male bean curd maker who, without any previous history of minor trauma, developed on the extensor side of the left upper arm an eczematous lesion that underwent gradual radial expansion. The lesion showed a well-defined, 7×10 cm infiltrated erythematous plaque with the central area healed and, at the upper and lower borders, adherent scales and crusts on the surface. Histological examination revealed granulomatous changes in the dermis, as well as sclerotic cells within giant cells and microabscesses. On culturing,Fonsecaea pedrosoi was isolated. The patient was treated with disposable chemical pocket warmers, which were secured over the lesion with a rather tight elastic bandage, so that they kept the affected area warm for 24 hours a day. After a month of such hyperthermic treatment, the erythema and infiltration had decreased considerably, and microscopic examination and culture of the crusts both yielded negative results. Examination of biopsy specimens of the lesion after the third month showed that it had cicatrized. The treatment was stopped after 4 months, and no relapse occurred. We also summarize the published results of local hyperthermic treatment of chromomycosis in Japan.     

Methods for rapid screening and isolation of bacteria producing acidic lipase: feasibility studies and novel activity assay protocols

Acidic lipase finds its commercial values in medical applications and bioremediation of food wastes. In this work, approaches for rapid screening of lipase-producing bacteria were developed and the feasibility assessment of the screening methods was performed. From food waste samples, the proposed screening procedures allowed isolation of sixteen pure bacterial strains expressing higher lipase activity at acidic pH (pH 6.0) than at alkaline pH (pH 9.0). To enhance the accuracy of lipase activity determination under acidic conditions, a novel assay procedure was also developed by deactivating lipase activity by microwave treatment prior to back titration. This additional step could minimize interferences arising from residual lipase activity during conventional direct back-titration methods in measuring lipase activity at acidic pH. Using the four strategies proposed in this work, the best acidic-lipase-producing isolate was obtained by strategy C (SSC) and was identified as Aeromonas sp. C14, displaying an optimal lipase activity of 0.7 U/ml at an acidic pH of 6.0.     

Models for Trypanosoma evansi (surra), its control and economic impact on small-hold livestock owners in the Philippines

Simple demographic and infectious disease models of buffaloes and other domestic hosts for animal trypanosomosis (surra) caused by Trypanosoma evansi were developed. The animal models contained deterministic and stochastic elements and were linked to simulate the benefit of control regimes for surra in village domestic animal populations in Mindanao, Philippines. The impact of the disease on host fertility and mortality were key factors in determining the economic losses and net-benefit from the control regimes. If using a high (99%) efficacy drug in surra-moderate to high risk areas, then treating all animals twice each year yielded low prevalence in 2 years; targeted treatment of clinically sick animals, constantly monitored (monthly), required 75% fewer treatments but took longer to reach a low prevalence than treating all animals twice each year. At high drug efficacy both of these treatment strategies increased the benefit over untreated animals by 81%. If drug efficacy declined then the benefit obtained from twice yearly treatment of all animals declined rapidly compared with regular monitoring and targeting treatment to clinically sick animals. The current control regimen applied in the Philippines of annual sero-testing for surra and only treating sero-positive animals provided the lowest net-benefit of all the control options simulated and would not be regarded as effective control. The total net-benefit from effective surra control for a typical village in a moderate/high risk area was 7.9 million pesos per annum (US $158,000). The value added to buffaloes, cattle, horses, goats/sheep and pigs as a result of this control was US $88, $84, $151, $7, $114 per animal/year, respectively.     

Effects of the level of early productivity on the lifespan of ewes in contrasting flock environments

Selection for high levels of prolificacy has allowed substantial improvements in the production efficiency of New Zealand (NZ) sheep farms, but the consequences on ewe lifetime performance are mostly unknown. In this study, the relationship between the level of prolificacy early in ewes’ productive lives and their probability to survive later (i.e. stayability) was evaluated in two contrasting NZ flock environments. Records were obtained from 6605 ewes from four ram breeder flocks representing either a moderate (n=2) or a highly variable (n=2) nutritional environment. All ewes lambed for the first time at 2 years of age and were mated the following year. The number of lambs born during the first 2 years of productive life (NLB_2–3) was used as a measure of early prolificacy. Effects of NLB_2–3 on stayability to 4, 5, 6, 7 and 8 years old were analysed using logistic regression. Curvilinear effects (logit-transformed) were detected (P<0.05) until stayability to 6 years and to 8 years old in the highly variable and the moderate environment, respectively. The NLB_2–3 that resulted in maximum expected stayability to various ages was 3.9 to 4.2, and 4.5 to 4.7 lambs in the highly variable and in the moderate flock environments, respectively. In addition, ewe stayability was reduced when the proportion of the litter that survived from birth to weaning (i.e. ewe rearing ability) was submaximal during the early productive life. High prolific ewes had a low rearing ability whatever the environment whereas the rearing ability of lowly prolific ewes was apparently more sensitive to the nutritional environment. The poor maternal performance of ewes with low levels of NLB_2–3 led to a premature culling by breeders whereas the high early reproductive effort associated with high levels of NLB_2–3 seemed to be at the cost of ewes’ survival, even in the moderate flock environment. In conclusion, the flock environment influenced the level of early prolificacy beyond which ewe longevity was reduced. It is suggested that further selection for high and early prolificacy in NZ flocks is likely to impair ewes’ lifetime productivity.