SUMMARYCompaction is one of the most destructive factors of soil quality, however the effects on the microbial community and enzyme activity have not been investigated in detail so far. The objective of this study was to evaluate the effects of soil compaction caused by the traffic of agricultural machines on the soil microbial community and its enzyme activity. Six compaction levels were induced by tractors with different weights driving over a Eutrustox soil and the final density was measured. Soil samples were collected after corn from the layers 0-0.

Aim: Mangroves provide a distinctive ecological environment that differentiates them from other ecosystems. This study deal to evaluate the frequency of microbial groups and the metabolic activities of bacteria and fungi isolated from mangrove, restinga and Atlantic forest soils. Methods and Results: Soil samples were collected during the summer and winter at depths of 0-2, 2-5 and 5-10 cm. Except for fungi, the counts of the total, sporulating, Gram-negative, actinomycetes, nitrifying and denitrifying bacteria decreased significantly in the following order: Atlantic forest > mangrove > restinga. The counts of micro-organisms decreased by 11 and 21% from the surface to the 2-5 and 5-10 cm layers, but denitrifying bacteria increased by 44 and 166%, respectively. A larger growth of micro-organisms was verified in the summer compared with the winter, except for actinomycetes and fungi. The average frequency of bacteria isolated from mangrove, restinga and Atlantic forest soils was 95, 77 and 78%, and 93, 90 and 95% for fungi, respectively. Bacteria were amylolytic (33%), producers of acid phosphatase (79%) and solubilizers (18%) of inorganic phosphate. The proportions of fungi were 19, 90 and 27%. Conclusion: The mangrove soil studied had higher chemical characteristics than the Atlantic forest, but the high salinity may have restricted the growth of microbial populations. Significance and Impact of the Study: Estimates of the microbial counts and activities were important to elucidate the differences of mangrove ecosystem from restinga and Atlantic forest.

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Saliva has garnered a lot of interest as a non-invasive, easy to collect, and biochemical rich sample for Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) based disease diagnosis. Although large number of studies have explored its potential, the preparation methods used differ greatly. For large scale clinical studies to aid translation into clinics, collection/processing methodology needs to be standardized. Therefore, in this study, we have explored different saliva collection (spitting-method A/cotton soaking-method B) and processing protocols (unprepared-TS, supernatant from centrifugation-CS, and drying-C) to find which gives the best ATR-FTIR signals. Analysis showed highest proteins, carbohydrates, amino acids, and nucleic acid + proteins/lipids in BTS, BCS, ACS, and BC, respectively. Notably, only BC shows 1377 cm-1 nucleic acid band is also uniquely identified in multivariate analysis. We conclude that collection-processing protocol should be based on biochemical that best gives a differential diagnosis.

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Sugarcane culture is replanted after five–eight successive harvests and intensely fertilised and mechanised. The influence on bacteria (total, nitrifying, denitrifying), fungi, microbial biomass-C, and dynamic processes (respiratory activity, N mineralisation, potential nitrification, P-solubilising activity) and enzymatic activities (dehydrogenase, urease, phosphatase) was studied for six successive harvests of the crop. The straw of the second and third harvest was burned. Soil microbial counts and activities were reduced after successive harvests. Fungi counts, N mineralisation, potential nitrification, and the P-solubilising, urease, and phosphatase activities decreased gradually from the first harvest to the third, increased again after the fourth, and then decreased again. Total, nitrifying, and denitrifying bacteria and fungi counts decreased, on average, 55, 22, 17, and 77%, respectively, in the sixth harvest in relation to the first. Reductions also occurred in microbial biomass-C (43%), respiratory activity (39%), N mineralisation (35%), potential nitrification (40%), and P-solubilising activity (35%). Reductions were observed in dehydrogenase (58%) and urease (36%) activities, but not in phosphatase activity. Successive sugarcane harvests may significantly influence microbial populations and activities, with harmful consequences to the C, N, and P cycles, and may decrease crop productivity.