脲原体属和人型支原体体外药物敏感性及其对喹诺酮类药物耐药机制分析:单中心回顾性研究

目的分析脲原体属和人型支原体体外药物敏感性特点,并分析其对喹诺酮类药物耐药的相关机制。方法回顾性总结北京协和医院2012年9月至2017年4月通过体外培养方法检测出的脲原体属和人型支原体标本,结合患者临床资料和菌种鉴定结果分析其体外药物敏感性特点。针对喹诺酮类药物耐药特点,采用普通PCR法扩增目的基因并测序,将测序结果翻译成蛋白质序列,与NCBI数据库中参考序列进行比对,检测DNA促旋酶(GyrA/GyrB)和拓扑异构酶Ⅳ(ParC/ParE)序列的突变情况。结果脲原体属混合人型支原体的体外敏感性总体低于脲原体属或人型支原体单独体外敏感性;除大环内酯类外,脲原体属对喹诺酮类、四环素类、交沙霉素、原始霉素、强力霉素的敏感性普遍低于人型支原体,但差异无统计学意义(P均>0. 05)。女性患者体内分离得到的脲原体属对阿奇霉素、红霉素、克拉霉素、氧氟沙星的体外敏感性较男性低(P均<0. 05)。微小脲原体对大部分抗菌药物的敏感性高于解脲脲原体,尤以对四环素的敏感率差异最大(98. 48%比72. 73%,差值25. 8%,P<0. 05)。在GyrA、 GyrB、 ParC和ParE的序列比对中,共发现21个突变位点,其中ParC S83L突变占96. 22%(51/53),为最主要突变位点;其余为ParC A136T突变、ParE R448K突变、GyrA L176F和ParC S83L联合突变等以及6个目前尚未报道过的突变位点,即ParC的L540F、R718W、Q767E、S789N、M828I和I831T突变。结论脲原体属和人型支原体的体外药物敏感性与感染种属有关,脲原体属的体外敏感性还与菌种、患者性别有关。对脲原体属喹诺酮类耐药的机制研究表明,单独ParC S83L突变是脲原体属对喹诺酮类耐药的主要机制,而新发现6个突变位点可能的作用机制仍有待深入研究。     

Cinetiques et mecanismes de l'action oxydative de l'hypochlorite sur les acides α-amines lors de la desinfection des eaux

In the field of water treatment, one increased concern over the quality of the environment requires an understanding of the fate of compounds generated by the addition of chemicals. One area of considerable interest is the stability of chlorine compounds produced when chlorine is added to natural water or swimming pool water. It is desirable to be able to predict the lifetimes of these harmful compounds under various conditions. In this study we examine for a range of hypochlorite α-amino acid ratios and pH, the kinetics and mechanism of the decomposition of α(N-chloro) and α(N,N-dichloro) amino acid, one of the products of chlorination.The interaction of chlorine with amino acids has been studied by several investigators Langheld (1909) was the first who discussed the decomposition of the α(N-chloro) amino acids. He noted that hypochlorous acid salts react with α-amino acids in the same manner as they do with amines to form monochlorinated or dichlorinated derivatives. Then, the decomposition of chloro-amino acids leads to the corresponding aldehydes or ketones, ammonia, carbonic acid, and sodium chloride. As an intermediate step Langheld assumed an imine formation.Wright (1936) and Pereira et al. (1973) have investigated the decomposition products of α(N,N-dichloro) amino acids. Their results indicate rapid formation of carbon dioxide, chloride ion, and the corresponding nitrile.Recently, many authors have investigated the rates of α(N-chloro) amino acids decomposition and the stability of its products (William and Wendy, 1979; Yoshiro et al., 1980; Le Cloirec-Renaud, 1984). However, they have neither differentiated between the decomposition of α(N-chloro) amino acid and α(N,N-dichloro) amino acid, nor have they demonstrated the combined effect of pH and molar ratio of hypochlorite and α-amino acid.In this study the hypochlorite oxidation of simple α-amino acids in aqueous solution has been investigated in the dark. The concentration of α(N-chloro) amino acid and α(N,N-dichloro) amino acid was monitored by DPD-fast titrimetric method and by measuring the absorbance at 255 and 293 nm respectively, this is illustrated in Figs 3 and 4. These results and the amino acids determination (O-phtalaldehyde—2 mercapto ethanol method) suggest that the intermediates α(N-chloro) and α(N,N-dichloro) amino acid are formed rapidly at an initial stage. Then, they decompose spontaneously by first order kinetics as shown in Table 1, to give a mixture of aldehyde and nitrile.When equimolar (1:1 mmol) amounts of hypochlorite and amino acid are used at pH 7, only aldehyde, carbon dioxide, chloride and ammonia are formed. However the corresponding nitrile compound appears, when operating condition allow the formation of α(N,N-dichloro) amino acid (acid pH or basic aqueous solutions with high molar ratio of hypochlorite and amino acid). This is illustrated in Table 2. The rate constant shows a dependence on pH, which is caused by the various forms that can arise from addition of protons to or removal of protons from the amino and carboxyl groups of the molecule William and Wendy, 1979). We assume an intermediate step of imine for the decomposition of both compounds: α(N-chloro) and α(N,N-dichloro) amino acid (scheme 6). The reaction should be considered as a spontaneous decarbonylation followed by a rapid hydrolysis of the imine. Scheme 7 illustrated how α(N,N-dichloro) amino acid can lead to the corresponding nitrile and aldehyde, however the α(N-chloro) amino acid gives only the corresponding aldehyde.The products of decomposition of α(N-chloro) amino acid are relatively stable in aqueous solution. Although we noted at pH = 3.5–5 that aldehyde react with chloramines and lead to the formation of corresponding nitrile, as shown in scheme 9.It appears that α(N-chloro) and α(N,N-dichloro) amino acid formed during the chlorination of natural or swimming pool water will degrade in a few hours to what are probably irritating products (like as aldehydes). The production of decomposition are a function of molar ratio of hypochlorite and amino acid and pH. However, since most natural water has a pH in the range of 5.5–9, there will be little variation of the rate of decomposition with pH. It seems that it is only temperature dependent.     

Controlling Dust Mites Psychrometrically – a Review for Building Scientists and Engineers

Abstract The literature for the control of dust mites by modification of the psychrometric conditions of the environment is reviewed from the standpoint of a building scientist or engineer, both to present to building science workers an envelope of micro-environment psychrometric conditions to use as control, and to highlight those areas of dust mite biology that require further research to complete the knowledge of the psychrometric envelope for dust mite viability. Some important data to allow tight specification of psychrometric control conditions are missing, viz.: the temperature dependence of critical equilibrium activity for Dermatophagoides pteronyssinus and Euroglyphus maynei; behaviour of dust mite populations under a fluctuating climate; and the difference between wild and laboratory populations. The widely quoted figure for dust mite control of 7 g/mg absolute humidity should be used with caution.     

Antibiotic resistance in coagulase negative staphylococci isolated from wastewater and drinking water

This study reports the antibiotic resistance patterns of coagulase negative staphylococci (CNS) isolated from a drinking water treatment plant (WTP), a drinking water distribution network, responsible for supplying water to the consumers (WDN), and a wastewater treatment plant (WWTP), responsible for receiving and treating domestic residual effluents. Genotyping and the 16S rRNA gene sequence analysis demonstrated a higher diversity of species both in the WTP (6 species/19 isolates) and WWTP (12 species/47 isolates) than in the WDN (6 species/172 isolates). Staphylococcus pasteuri and Staphylococcus epidermidis prevailed in the WTP and WDN and Staphylococcus saprophyticus in the WWTP. Staphylococci with reduced susceptibility (resistance or intermediary phenotype) to beta-lactams, tetracycline, clindamycin and erythromycin were observed in all types of water and belonged to the three major species groups. The highest resistance rate was found against erythromycin, presumably due to the presence of the efflux pump encoded by the determinant msrA, detected in the majority of the resistant isolates. This study demonstrates that antibiotic resistant CNS may colonize different types of water, namely drinking water fulfilling all the quality standards.     

ANTICIPATED AIR POLLUTION TOLERANCE OF SOME PLANT SPECIES CONSIDERED FOR GREEN BELT DEVELOPMENT IN AND AROUND AN INDUSTRIAL/URBAN AREA IN INDIA: AN OVERVIEW

Vegetation naturally cleanses the atmosphere by absorbing gases and some particulate matter through leaves. Plants have a very large surface area and their leaves function as an efficient pollutant‐trapping device. Some plants have been classified according to their degree of sensitivity and tolerance towards various air pollutants. Sensitive plant species are suggested to act as bio‐indicators. Levels of air pollution tolerance vary from species to species, depending on the capacity of plants to withstand the effect of pollutants without showing any external damage. In this study, the air pollution tolerance index (APTI) of 30 plant species has been evaluated. High values of APTI were recorded in Mangifera indica, Moringa pterydosperma, Cassia renigera and Ailanthus excelsa. The anticipated performance index (API) of 30 plant species has also been evaluated for green belt (GB) development in and around an industrial urban area in India. Using APTI and this performance rating, the most tolerant plants have been identified.     

Comparative study on organic constituents in polluted and unpolluted inland aquatic environments—III: Phenols and aromatic acids in polluted and unpolluted waters

Phenols and aromatic acids were analysed in polluted river waters in the Tokyo area and in water from an unpolluted river, brook, reservoir and in pond waters from the Ogasawara (Bonin) Islands. The phenolic acids (p-hydroxybenzoic, vanillic, syringic, p-coumaric and ferulic acids) and o- and m-hydroxybenzoic acids were found in the waters of the Tokyo area and Ogasawara Islands at a concentration of generally less than 1 μg 1⁻¹, but pentachlorophenol, bisphenol A, terephthalic and trimesic acids were not identified in the waters of the Ogasawara Islands. It was confirmed that the major sources of these phenolic acids are vascular plants and their detritus, while pentachlorophenol, bisphenol A and terephthalic acids are mainly attributed to human activities. It was also established that these phenolic acids are commonly distributed in polluted and unpolluted waters.The p-coumaric and ferulic acids as carbon (CFC)/total organic carbon and CFC/extractable organic carbon with ethyl acetate values suggested that the contribution of vascular plants and their detritus to the waters between the Tokyo area and Ogasawara Islands are near equal. According to the syringic acid/vanillic acid ratios, it is probable that the relative contribution of angiosperms to gimnosperms for the waters of the Tokyo area is smaller than those of the Ogasawara Islands.     

Measurement of dissolved organic nitrogen forms in wastewater effluents: concentrations, size distribution and NDMA formation potential

Dissolved organic nitrogen (DON), which may act as a nutrient and a disinfection by-product precursor, accounts for most of the dissolved nitrogen in nitrified-denitrified wastewater effluents. To gain insight into the behavior of wastewater-derived DON in engineered and natural systems, samples from treatment plants employing a range of different processes were characterized by several different methods. Dissolved free and combined amino acids accounted for the majority of the identifiable DON. Combined amino acids typically accounted for less than 10-20% of the wastewater-derived DON. Other organic-nitrogen containing species such as EDTA and humic substances from the water source only accounted for a few percent of the remaining DON. The remaining DON mainly consisted of hydrophilic, low-molecular weight compounds, capable of passing through a 1 kDa ultrafilter. This fraction of the DON also contained most of the precursors of N-nitrosodimethylamine (NDMA). The chemical properties of wastewater-derived DON pose challenges to designers of wastewater treatment plants because most physical and chemical treatment processes will not remove low-molecular weight, hydrophilic compounds.     

Characterization of activated sludge exopolymers from various origins: a combined size-exclusion chromatography and infrared microscopy study

High-pressure size-exclusion liquid chromatography and infrared microscopy were coupled to investigate the molecular weight and nature of extracellular polymeric substances (EPS) from various activated sludges. Six main families of compounds (proteins, polysaccharides, organic acids, lipids, mineral phases) were found either as a single molecule or as associations. The molecular weight of proteins varied from small (10 kDa) to large (600 kDa) sizes, while all polysaccharides were smaller than 1 kDa. Association of different molecules implied the presence of species large in size. The EPS chromatographic fingerprints of sludge from various origins remained stable in normal operating conditions, but were drastically modified during settling crises. In poor settling conditions, the EPS with smaller molecular sizes always prevailed and large polymers were underrepresented. The EPS identified in activated sludge were collected in a chemical database which provides the basis for comparison of municipal and industrial wastewater treatment plants (WWTP).     

Survival of the House Dust Mite,Dermatophagoides farinae,at High Temperatures (40–80°C)

Abstract Experiments were conducted to evaluate the survival time of randomly selected female D. farinae exposed to temperatures from 40 to 80°C and relative humidities (RHs) between 10 and 90%. Significant temperature effects were found on the length of time mites can survive under those conditions. The time needed to induce 100% mortality for female D. farinae held at 40°C varied between 39 and 84 h. At 70 and 80°C, all mites died within 5 minutes. At 50°C and above, RH had little influence and temperature alone was the determining factor for mite survival. The length of survival time decreased precipitously between 40 and 50°C, suggesting that a loss of physiological integrity of female D. farinae probably occurred in this range. The results of this study indicated that the technique of raising temperatures to above 40°C for a short duration can be used to reduce living house dust mite populations in homes significantly.     

Antimicrobial multiresistance in bacteria isolated from freshwater Chilean salmon farms

The intensive use of antimicrobial agents, mainly oxytetracycline, to prevent and control bacterial pathologies in Chilean salmon culture is a frequent practice. A total of 103 gram-negative oxytetracycline-resistant bacteria recovered from various sources of 4 Chilean freshwater salmon farms were identified and investigated for their susceptibility patterns to various antibacterial agents, by using an agar disk diffusion method. Antibacterial resistance patterns of isolates were not correlated with bacterial species or strain source. A high number of bacteria resistant to amoxicillin, ampicillin. erythromycin, and furazolidone, as well as an important frequency of bacterial resistance to florfenicol, chloramphenicol, cefotaxime and trimethoprim-sulfamethoxazole was found. On the contrary, the proportion of bacteria resistant to gentamicin, kanamycin, flumequine and enrofloxacin was rather low. Resistant microflora showed a high taxonomic variability and mainly consisted of non-fermenting bacteria (77.7%). These strains mainly belonged to the species Pseudomonas fluorescens (29), Aeromonas hydrophila (10), Stenotrophomonas maltophilia (6), isolated from salmon fingerlings, and Acinetobacter lwoffii (5) isolated from pelletized feed. The occurrence of simultaneous resistance to various antibacterials was frequent. We observe a high frequency of bacteria resistant to 6-10 antibacterials (74 strains), and antibiotic resistance index (ARI) values ranging from 0.38 to 0.48 for the four salmon farms studied. These results suggest that Chilean salmon farms might play a role as reservoirs of antibacterial multiresistant bacteria, thus prompting the necessity for a more restrictive attitude towards the intensive use of antibacterials in salmon farming.     

Cryopetrophyte communities of the West Sayan Ridge

Abstract

The paper presents research in eco-coenotic features of cryopetrophyte communities of the Osevoi Ridge in the Western Sayan Mts. All communities studied are in the association Saxifrago oppositifoliae–Rhodioletum quadrifidae. This association includes all communities with a predominance of alpine and arctalpine petrophytes, which are largely facultative and obligate calciphile plants. The coenoflora of the association Saxifrago oppositifoliae–Rhodioletum quadrifidae is represented by 54 species of higher vascular plants. The dominant species in its structure are those of Holarctic distribution and species generally confined to the Altai-Sayan mountain region, with Papaver pseudocanescens, Poa smirnowii, Sajanella monstrosa, Saussurea foliosa and Saxifraga melaleuca being endemics. In the structure of the belt-zonal groups, arctalpine and alpine species dominate. Among ecological groups, obligate and facultative petrophytes, generally cryophytes, are dominant. The predominance of some particular belt-zonal and ecological groups of species indicates greater specificity of the environmental conditions in which the communities were formed and are currently being formed.     

Extended Spectrum Beta-Lactamase and Metallo Beta-Lactamase Producing Pseudomonas Species Isolated From Fish Pond Water in Ibadan,Nigeria

ABSTRACT

Gram-negative bacteria that produce Extended-spectrum beta-lactamase (ESBL) and metallo beta-lactamase (MBL) show resistance to beta-lactam antibiotics. This study was to determine Beta-lactamases-producing Pseudomonas species in fish ponds. Pseudomonas species isolated from aquaculture water samples using Pseudomonas base agar were characterised biochemically. The detection of ESBL and MBL was made by double disc synergy and imipenem-EDTA combined disc methods, respectively. Antimicrobial susceptibility was by disc diffusion method. The 94 Pseudomonas species isolated comprised P. aeruginosa (62.8%), P. stutzeri (14.9%), P. putida (9.8%) and P. fluorescens (12.8%). P. aeruginosa 16 (16.3%) and P. stutzeri 4 (4.3%) produced ESBL, but 2 (10%) P. aeruginosa and 1 (5%) P. stutzeri produced MBL. Resistance of ESBL producers to trimethoprim was 55.5% and 7 (35.0%) were multidrug resistant. Detection of ESBL and MBL in Pseudomonas spp. from this study implies environmental health risk. Antibiotics misuse in aquaculture and discharge of untreated aquaculture wastewater into the environment should be discouraged.     

A simplified buffer capacity model for sanitary landfill leachate

An initial simplified buffer capacity model for landfill leachate is postulated and compared to that of two different leachate samples from the same landfill. This equilibrium model is based on the products of anaerobic decomposition. The number of species is reduced by considering all organic acids as acetic acid. This simplification reduces the number and complexity of chemical analyses required to measure the species, and also, lessens the calculations involved.The model predicts maximum buffer capacity pH within a ΔpH = 0.35, and underpredicts the magnitude by 16%.     

Exploitation de bambous (Sinarundinaria alpina (K. Schum.) C.S. Chao & Renvoize), cause des conflits entre le Parc National de Kahuzi-Biega et la population environnante: stratégie de conservation et de résolution de conflit

Sinarundinaria alpina is a species of mountain bamboo which is a source of various conflicts between the managers of the Kahuzi-Biega National Park (KBNP) and surrounding communities. This mountainous species is threatened by these communities to meet their need for various uses. Six permanent plots of 3 hectares were set between 2000–3000 metres above sea level and floristic inventories were made. In addition, information related to anthropogenic threats related to bamboo exploitation was recorded. All data were analysed using quantitative statistical parameters. Results suggest the existence of 196 species in these six permanent plots of the group Bamboo. The position of this Sinarundinaria alpina vegetation in the dynamic rainforest recovery dynamics is confirmed by the presence of trees and tree-nurseries of these trees. Fifty-three species, 27% of the plants observed, including Sinarundinaria alpina seedlings, contribute to the daily feeding of great apes, mainly Grauer’s Gorilla (Gorilla beringei graueri). This forest appears to be one of their critical habitats. The decrease in the area covered by bamboos is due primarily to anthropogenic activities but also some natural hazards (expansion of Sericostachys scandens, natural fading of Bamboo and attacks by beetles). Following these findings, conservation strategies were proposed. Several strengths were noted, including multiplication of bamboo nurseries and distribution of seedlings to local communities. This can be seen as a strong development of this sector in the future. This study is a preliminary assessment for further investigation.     

Resources of medicinal plants in the Kuznetsky Alatau

The paper aims to study the resources of medicinal plants in the the Kuznetsky Alatau. Eighty-four species of vascular plants applied in scientific medicine have been identified, 35 of which have industrial reserves of raw material (resources of categories I and II). The remaining 49 species are not recommended for industrial procurement. Reserves of raw materials have been ascertained for 12 commercial species among which Paeonia anomala (9138 t), Polygonum bistorta (3200 t), Bergenia crassifolia (571 t), Sorbus sibirica (346 t), Veratrum lobelianum (342 t) and Rhaponticum carthamoides (328 t) have been assessed to have the biggest volumes of raw materials’ reserve. Five commercial species of medicinal plants, namely B. crassifolia, P. bistorta, Bupleurum multinerve, P. anomala and R. carthamoides, and a rare valuable medicinal plant Rhodiola rosea are confined to mountain habitats. We determined the optimal part of the cenocomplex, the conditions of habitation and the density of reserves for these species. The paper makes recommendations for their sustainable use. Despite the relatively small territory of the Kuznetsky Alatau, it is considered to have great potential for harvesting of medicinal plants.     

Chemical and biochemical parameters of cultured diatoms and bacteria from the Adriatic Sea as possible biomarkers of mucilage production

Bacteria and diatom strains from the Adriatic Sea were investigated, under standard and altered environmental conditions, for carbohydrate production and for the presence of specific biomarkers. Algae from P-depleted cultures showed an increase in extracellular carbohydrate production, a significantly lower chlorophyll a content and unchanged total lipid levels. However, the fatty acid composition of algal cultures was severely affected by low P levels, in that, total saturated and monounsaturated fatty acids increased and total polyunsaturated fatty acids decreased. Marine heterotrophic bacteria resulted enriched by 4 to 6 orders of magnitude in mucilage samples respect to surrounding seawater, unlike other groups of bacteria such as the non-halophylic heterotrophs. The major fatty acids detected in bacteria were 16:0 and 18:1n-7; the uneven fatty acids 17:0i, 17:0 and 17:1 also constituted an important component of various strains and, as a result, the total monounsaturated fraction represented the main component of total fatty acids. All the mucilage samples analysed shared the same general fatty acid composition features with a high amount of saturated components, especially 16:0; typical marine polyunsaturated fatty acids, such as 20:5n-3 and 22:6n-3, were found at very low levels. With regard to the sterol composition, the analysed algal species and bacteria showed that different compounds prevailed in the different species, and under P-deprivation sterol distribution resulted differently affected in the various algal species. In mucilage samples an overall prevalence of cholesterol was observed and, among 4alpha-methylsterols, constantly present, dinosterol prevailed in all samples. Vibrational IR spectroscopic analyses confirmed the main results obtained with the GC analysis: a higher unsaturation degree in nutrient replete diatom cultures than in P-depleted ones, a lower amount of P-containing compounds in the latter, bacterial lipid profiles with a high amount of free carboxylic acids and/or ketones and a low unsaturation degree and, finally, mucilage samples with a very low unsaturation degree. All these results allowed some speculations on the involvement of the various microbial and phytoplankton components in mucilage genesis.     

Carbon source utilization‐based metabolic activity of Salmonella Oranienburg and Salmonella Saintpaul in river water

The presence of introduced or non‐native bacteria in river water can create a selective pressure due to their ability to overcome fluctuations in physicochemical conditions and carbon source availability. The carbon source concentrations (monosaccharides and polysaccharides), physicochemical parameters (turbidity, total dissolved solids, biochemical oxygen demand, temperature and pH) and metabolic activity of Salmonella Oranienburg and Saintpaul were determined in water from the central Sinaloa state rivers. This study's results revealed that the carbohydrate availability and physicochemical conditions of river water make it a suitable niche for the establishment of Salmonella serotypes. Metabolic profiles showed that Salmonella Typhimurium could consume a wide variety of carbon sources but only at moderate levels; in contrast, Salmonella Oranienburg and Salmonella Saintpaul demonstrated intense carbon source utilization of a limited diversity of carbon sources. Carbohydrates, amino acids and carboxylic acids were the metabolites most utilized by the environmental Salmonella strains, demonstrating their superior ability to adapt to and survive in river water.     

Pollination ecology and seed production of some species of the genus Pedicularis L. in the highlands of Altai

Abstract

The paper presents data on the pollination ecology and seed production of three Pedicularis L. species in the high mountains of Altai. It was determined that the investigated species are highly specialised entomophiles. Specialisation to entomophily is expressed in a number of adaptations: the presence of nectar in flowers of Pedicularis, pollen and secondary attractants (visual and tactile) that attract insects, as well as specific morphological structures which facilitate the process of pollen hitting a certain area of the body of the insect. Hercogamy and protogyny and gradual explication of the flowers in the inflorescence and their long lifespan in wide ranges of temperature and humidity are also adaptations to cross-pollination. The investigated species have high fertility and viability of the pollen grains. Seed production ranges from 57.1 to 261.3 seeds per stem. The seeds have organic rest. Promoting agents of seeds germination of the investigated species are cold stratification in conjunction with the gibberellic acid treatment. The biology of louseworts is peculiar because they combine autotrophic feeding with parasitism on other higher plants. The lack of strict species specificity in the choice of host plants was discovered. The complex of host plants includes 27 species.     

华南地区适宜岩质坡面绿化的攀援植物筛选

在分析岩质坡面植物生长主要限制因子——土壤干旱与瘠薄的基础上,从华南地区山地植被中引种栽培47种攀援植物,对其生物学特性、生活习性、抗旱性等关键指标进行了试验研究。根据试验及大田栽培观察结果,采用“百分法”综合评选出19种适宜岩质坡面绿化的攀援植物,为岩质坡面绿化与植被恢复提供了更多可参选的植物种类,以满足绿化中对景观多样性、植物多样性的要求。     

Susceptibility of green and conventional building materials to microbial growth

Green building materials are becoming more popular. However, little is known about their ability to support or limit microbial growth. The growth of fungi was evaluated on five building materials. Two green, two conventional building materials and wood as a positive control were selected. The materials were inoculated with Aspergillus versicolor, Cladosporium cladosporioides and Penicillium brevicompactum, in the absence and presence of house dust. Microbial growth was assessed at four different time points by cultivation and determining fungal biomass using the N‐acetylhexosaminidase (NAHA) enzyme assay. No clear differences were seen between green and conventional building materials in their susceptibility to support microbial growth. The presence of dust, an external source of nutrients, promoted growth of all the fungal species similarly on green and conventional materials. The results also showed a correlation coefficient ranging from 0.81 to 0.88 between NAHA activity and culturable counts. The results suggest that the growth of microbes on a material surface depends on the availability of organic matter rather than the classification of the material as green or conventional. NAHA activity and culturability correlated well indicating that the two methods used in the experiments gave similar trends for the growth of fungi on material surfaces.