Biodeterioration of painted mortar surfaces in tropical urban and coastal situations: Comparison of four paint formulations

Four different architectural acrylic paint formulations were tested by exposure to weathering for 7 years in the urban site of São Paulo and the coastal site of Ubatuba, South-East Brazil. Surface discolorations and detachment of coatings were assessed and the components of the biofilms were identified by standard microbiological methods. The painted surfaces of the mortar panels were much more discolored in Ubatuba, where major components of the biofilms were the cyanobacteria Gloeocapsa and Scytonema. In two of the four paint films, a pink coloration on the surface at this coastal site, caused mainly by red-pigmented Gloeocapsa, produced high discoloration ratings, but low degradation (as measured by detachment). Biofilms in São Paulo contained the same range of phototrophs, but in lesser quantity. However, fungal numbers, as determined by plating, were higher. Detachment ratings in this urban site were only slightly lower than in Ubatuba. The matt paint performed worst of the four, with silk and semi-gloss finishes giving lowest biodeterioration ratings. The matt elastomeric paint performed well at both sites, apart from becoming almost 100% covered by the pink biofilm in Ubatuba. Unpainted mortar panels became intensely discolored with a black biofilm, showing that all the paints had achieved one of their objectives, that of surface protection of the substrate. The value of PVC (pigment volume content) as an indicator of coatings biosusceptibility, is questioned.     

Potentially toxic and harmful microalgae from coastal waters of the Campania region (Tyrrhenian Sea, Mediterranean Sea)

A total number of 40 potentially toxic microalgae and 5 taxa causing discolorations have been identified along the coasts of the Campania region (South Tyrrhenian Sea, Mediterranean Sea). This number is based on results of over 20 years of research at a coastal station in the Gulf of Naples, 4 years of monitoring activity along the Campania coasts and of a series of scattered and sporadic observations. Several species of the recently erected genera Karenia and Takayama are reported for the first time in the area. Information on the period of highest abundances or most probable period of occurrence indicates the late spring and summer as the periods of maximum risk of harmful events. Despite the variety of potentially toxic species, no human health problems nor fish kills have ever been recorded in Campania. The reasons for this apparent paradox are probably to be found in the ecological factors that regulate the abundance, toxicity and spatial distribution of the potentially harmful species and reflect as well the relatively low number of aquaculture plants in the area.     

Gross and microscopic morphology of lesions in Cnidaria from Palmyra Atoll, Central Pacific

We conducted gross and microscopic characterizations of lesions in Cnidaria from Palmyra Atoll, Central Pacific. We found growth anomalies (GA) to be the most commonly encountered lesion. Cases of discoloration and tissue loss were rare. GAs had a focal or multi-focal distribution and were predominantly nodular, exophytic, and umbonate. In scleractinians, the majority of GAs manifested as hyperplasia of the basal body wall (52% of cases), with an associated absence or reduction of polyp structure (mesenteries and filaments, actinopharynx and tentacles), and depletion of zooxanthellae in the gastrodermis of the upper body wall. In the soft corals Sinularia sp. and Lobophytum sp., GAs exclusively manifested as prominent hyperplasia of the coenenchyme with an increased density of solenia. In contrast to scleractinians, soft coral GAs displayed an inflammatory and necrotizing component with marked edema of the mesoglea, accompanied by infiltrates of variably-sized granular amoebocytes. Fungi, algae, sponges, and Crustacea were present in some scleractinian GAs, but absent in soft coral GAs. Fragmentation of tissues was a common finding in Acropora acuminata and Montipora cf. dilatata colonies with tissue loss, although no obvious causative agents were seen. Discoloration in the zoanthid, Palythoa tuberculosa, was found to be the result of necrosis, while in Lobophytum sp. discoloration was the result of zooxanthellar depletion (bleaching). Soft corals with discoloration or tissue loss showed a marked inflammatory response, however no obvious causative organisms were seen. Lesions that appeared similar at the gross level were revealed to be distinct by microscopy, emphasizing the importance of histopathology.     

Effect of temperature on light-limited growth of the harmful diatom Eucampia zodiacus Ehrenberg, a causative organism in the discoloration of Porphyra thalli

The diatom Eucampia zodiacus Ehrenberg is one of the harmful diatoms which indirectly cause, through nutrient depletion, discoloration of Porphyra thalli. The effect of temperature on light-limited growth of E. zodiacus was examined at 13 irradiance levels (5–350 μmol m⁻² s⁻¹) in combination with five temperatures (8.0–25.0 °C). The results showed that all the parameters of growth-irradiance curves, such as the maximum growth rate (μ_m), half saturation constant (K_s), threshold value of irradiance (I₀) and saturation irradiance for growth (S), increased with increasing temperature. On the basis of the relationship between temperature and growth-irradiance curves and seasonal fluctuation of the light environment in Harima-Nada, the effect of irradiance on the population dynamics of E. zodiacus during the period from October to March was evaluated using two indices, depth of the threshold irradiance for growth (D_t) and depth where a half of its maximum growth rate is attained (D_k). D_t and D_k remained almost stable from October to December, but gradually increased in early March. This indicates that the range of depth at which E. zodiacus was able to grow increased markedly in early spring when E. zodiacus blooms in Harima-Nada. As the vegetative cells of E. zodiacus tend to distribute in relatively deeper water layers, where growth is limited by irradiance, the increase in the depth range over which E. zodiacus is able to grow is concluded to be an important factor allowing development of its blooms.     

菜籽降压肽双酶水解液脱色工艺的研究

用活性炭对菜籽降压肽双酶水解液进行脱色处理,采用单因素试验以及单因素试验基础上的正交试验法。考察活性炭用量、pH、温度、时间对水解液脱色率、肽损失率、活性及ACE抑制率的影响。正交试验优化结果表明,菜籽降压肽双酶水解液脱色最佳工艺为活性炭的用量为1%、脱色pH值为3.0、脱色温度为80℃、脱色时间为50 min,在此条件下脱色率为85.52%、ACE抑制率为57.83%、活性损失率为5.69%。