碱法草浆造纸蒸煮黑液厌氧生物降解性及其主要微生物类群研究

造纸行业是造成我国水环境有机污染物的重要污染源之一，其水污染的特点是小厂多、草浆多、工艺落后、污染扩散面广、造成废 水排放量大，每年排放的废水量约39亿立方米，占全国工业废水排放量的1/6，其中有机污染物（以BOD5计）160万吨左右，约占全 国工业废水中有机污染物总量的1/4。尤以占全国制浆造纸行业90%以上的碱法草浆造纸厂的蒸煮黑液量大面广，除含有机物外，还 含有木质素、残碱、硫化物、氯化物等污染物，属于PH值高、色度深、难于治理的高浓度有机废水，对水体污染特别严重，各地要 求治理呼声很高，急待研究并尽快找出各种有效的治理途径。对于碱法草浆蒸煮，黑液高浓度废水的治理，有各种方法，根据国内 的研究进展和我们已有试验工作表明，最经济有效，具有实用价值，在生产上可获得成功是厌氧处理法。近10多年来，国外关于高 效厌氧处理技术研究进展迅速，并出现了多种多样的工艺设备，如高效厌氧生物反应器，并在实用化方面取得了很大成绩，建立了 生产性装置，达到了高负荷运行，效果良好。本试验是根据我们已有研究基础，针对我国国情，对小型制浆造纸厂水污染防治除了 开发碱回收及各种综合利用技术外，要特别加强废水(废液)实用技术研究的指导思想，本试验采用改进型的上流式厌氧污泥床反应 器，设计了两种试验方案，通过试验结果如下。1. 试验方案I—碱法草浆黑液酸化和厌氧发酵I号UASB反应器动态模型试验结果表 明：(1). 采用中温35℃±1℃高效厌氧反应器USAB内装有填料(陶粒)和三相分离器，具有保持高浓度生物量和防止污泥流失的特点 ，污泥浓度Vs 可达30%以上，因而具有高效、节能、产能、滞留期短的优点，当进水CODcr在7500-10000mg/l，HRT由7天缩短到3天 ，有机容积负荷在1.22gCODcr/l·d-3.43gCODcr/l·d时，CODcr平均去除率可达55%-45.5%，最高CODcr去除率可达60.2-63.5%， BOD5去除率可达75.9-83.2%,沼气容积产气率可达0.29-0.67l/l·d，每克CODcr转化为沼气产率达0.39-0.48l/gCODcr·d，CH4含量 65.8-75.5%。厌氧发酵出水再用化学法进行后处理脱除难降解的木质素，CODcr总去除率达80%以上。(2). 动态试验结果表明：采 用酸化—厌氧发酵处理黑液工艺合理，技术路线可行。2. 试验方案II—黑液用化学法(Hcl)去除木质素进行厌氧发酵，II号UASB反 应器动态模型试验结果表明：(1). 采用中温35℃±1℃高效厌氧反应器UASB(内有软填料)，当进水CODcr7000-13000mg/l左右，HRT 由6天缩短到1天，有机负荷由0.98gCODcr/l·d增加到11gCODcr/l·d时，COD平均去除率均可稳定在70-77%，BOD5去除率为87.3- 93.1%，沼气容积产气率0.21-2.6l/l·d，每克CODcr转化为沼气产率为0.39-0.48l/gCODcr·d，高的可达0.53l/gCODcr·d，转化 率较高，CH4含量63-70%。(2). 试验证明碱法草浆黑液物化预处理—厌氧发酵处理的技术路线也是可行的，工艺合理、效果较好。 在有条件的工厂可采用。3.厌氧发酵阶段几大类群微生物计数表明：(1). 当发酵工艺和运行处于相对稳定状态时，微生物群体的 组成也达到相对的稳定，各类微生物之间保持动态平衡关系。当产乙酸菌的数量为107-108个/ml时，产甲烷菌的数量为105-106 个/ml，当产乙酸菌数量为106-107个/ml时，产甲烷菌的数量为103-105个/ml。(2).稳态运行条件下，黑液预处理为甲烷发酵创造 了有利的生态环境，获得了较好的处理效果和较高的COD转化为沼气的产率0.39-0.48l/g·CODcr·d，反应器中形成较为稳定而数 量较下水污泥中高1-2个数量级的厌氧发酵微生物区系组成。这一结果为黑液厌氧发酵提供了微生物理论依据。Paper industry is one of the important pollution source of water environment in our country. Its character of water pollution is many small factories, much grass pulp, disadvantageous technique, large preading area of pullution. Its effluent makes up 1/6 of whole country's industry wastwater. Its organic pollutant accounts 1/4 of whole country's. Alkaline grass paper pulp effluent with pollutants such as ligoin, remaining alkali sulfide, chloride besides organic material, is a kind of high concentrate organic wastewater which has high PH walug, dark colour and is difficult in treatment. There is urgent require to find ways to treat the wastewater. There are different ways to treat alkaline paper grass pulp effluent. According to the research advances and our experiment work, the most economical and useful way is anaerobic degradation which was advanced quick in last ten years. In the control of waste water of small pulp paper mill, the study of wastewater utilization technology should be emphasized, besides alkaline retrieving and different kinds of comprehensive utilization technology. Our experiment used modified UASB(Upflow Anaerobic Sludge Blanket Reactor). Two kinds of plan were disgned. The results are lined below. 1. The first experiment plant-aciding black pulp effluent and methanogenic digestion. The dynamic model experiment results of I-UASB reactor showed: (1)The mesophilic(35℃±1℃)high effect UASB reactor having haydite and threee state seperation in it had the character of keeping high bioimass concentration and preventing losss of sludge. It had advantages of high effect, energe saving, energe prodcing and short HRT(Hydroulic retention time). When the influent COD was 7500-10000mg, HRT was shortened from 7 days to 3days, organic loading rate was 1.22g-3.43COD/l· d, the average COD removal efficiency was 55%-45%. The highest COD efficiency was 60.2-63.5%, BOD removal of 75.9 -83.4% was achieved. Biogass production rate were up to 0.29-0.67l/l·d. Biogass converted efficiency from every gram of COD could reach 0.39-0.48l/gCOD·d. Methane content was 65.0-75.5%. Chemical method was used to deplate lignin in anaerobic digestion effluent. Total COD removal efficiency could be more than 80%. (2)Using aciding annaerobic digestion to treat the black effluent was reseanable in technique and technology. 2. The second experiment plan-anaerobic digestion was used after the chemical method was used to deplate lignin in the black effluent. The result of dynamic experiment of II-UASB reactor showed: (1)High effect mesophilic (35℃±1℃)UASB reactor having soft slaffing in was used. When influent COD was about 7000-13000mg/l, HRT was shortened from 6 days to 1 day and organic loading rate was increased from 0.90 to 11g COD /l·d, average COD removal efficiency remained stable on 70-77%. BOD, removal efficiency was between 87.3-93.1%. Biogass production rate was 0.2-2.6l/l ·d .Biogass converted efficiency from a gram of COD was 0.39-0.481/gCOD·d with the high value of 0.53l/gCOD·d. Methane content was 63-70%. (2)The way that using physical, chemical Pre-treatment-anaerobic digestion to treat alkaline black effluent is feasible and can be used in some factories when the condition exists. 3. Counting of several class of microoganisms in anaerobic digestion stage showed: (1)As the disgestion was in stable motion, the compositon of microorganic colony could get relative stable. Dynamic balance was remaining among different kinds of microorganism such as methanogenic bacteria, Acidogenic bacteria, sulfate reducing bacteria, and heterotrophic bacteria. (2)Under stable motion, the pre-treatment of black effluent produced favourable eco-enviroment for methanegenic digestion. Good treatment effect and high biogass convertent efficiency from COD(0.39-0.48l/g·COD· d)were gotten. Some stable and high quantity(10-100times more than sewage sludge)microorganism colony were formed in the reactor. This result provided theoretical basis for anaerobic digestion of black effluent.

有机碳对混合菌群亚硝酸盐氮氧化的影响

自养硝化过程在自然界氮素循环和污水处理系统脱氮过程中起着关键作用。因此，了解有机碳对硝化的影响和硝化菌与异养菌之间的竞争对微生物生态学和污水处理系统设计都很重要。目前对氨氧化到硝酸盐氮过程的研究文献很多，但对亚硝酸盐氧化过程在异养菌的存在下如何受到有机碳影响的研究甚少。本文从生理生化指标、基因组学、蛋白组学三方面考察了在实验室条件下有机碳（乙酸钠）对硝化细菌和异养菌组成的混合菌群的硝化性能、菌群结构及代谢功能的变化的影响。 全文分为两大部分： 第一部分为乙酸钠对游离态硝化混合菌群的硝化性能和菌群结构的短期影响。混合菌株先在自养条件下进行连续培养，两个月后硝化速率达到20 mg N/(L·d)；而后离心收集菌体进行批式实验。在批式反应器中，初始亚硝氮均为126mg N/ L，乙酸钠-C 与亚硝酸盐-N 的比分别为0，0.44，0.88，4.41，8.82。结果表明：在低C/N 比（0.44 和0.88）时，亚硝酸盐去除速率比C/N=0 下高，细菌呈现一次生长；而在高C/N 比（4.41 和8.82）时，出现连续的硝化反硝化，亚硝酸盐去除率仍比对照下高，细菌呈现二次生长。不同C/N 比下微生物群落明显不同，优势菌群从自养和寡营养细菌体系（包括亚硝酸盐氧化菌，拟杆菌门,α-变形菌纲,浮霉菌门和绿色非硫细菌下的一些菌株）过渡到异养和反硝化菌体系 （γ-变形菌纲的菌株尤其是反硝化菌Pseudomonas stutzeri 和P. nitroreducens 占主导）。 第二部分为乙酸钠对硝化混合菌群生物膜的硝化性能和菌群结构的长期影响。接种富集的硝化混合菌群于装有组合式填料的三角瓶中，于摇床中自养培养；两个月后填料上形成生物膜的硝化速率达到20 mg N/ (L·d)；而后进行长期实验，每12 小时更换混合营养培养基（亚硝氮约200 mg N/ L，C/N 比同上）。结果显示：相较于C/N 比=0 时的亚硝酸盐氧化反应来说，低C/N 比出现了部分的反硝化，而高C/N 比则是几乎完全的反硝化。与对照比，C/N=0.44 时亚硝酸盐氧化速率并未受乙酸钠的影响，反而上升了，但C/N=0.88 时亚硝酸盐氧化速率有所下降。菌群结构分析表明自养对照与混合营养下微生物群落的不同；PCR-DGGE未检测出混合营养下硝化杆菌的存在，而显示异养菌尤其是反硝化菌的大量存 在。荧光定量PCR 结果表明随C/N 比上升，硝化杆菌数量从2.42 × 104 下降到1.34× 103 16S rRNA gene copies/ ng DNA，反硝化菌由0 增加至2.51 × 104 nosZgene copies/ ng DNA。SDS-PAGE 的结果表明不同C/N 比下的蛋白组较为复杂且呈现一定的差异性。 有机碳对亚硝氮氧化及微生物群落的影响很复杂，本文分别讨论了对游离态和生物膜固定态两种状态的混合菌群相应的短期和长期影响研究。研究发现，有机碳并非一定带来硝化的负影响，如果控制在适当的C/N 比范围，有机碳是有利于亚硝氮氧化的。这些发现阐明了有机碳和硝化反硝化的关系，填补了硝化微生物生态学上的空白，对污水处理系统中减少异养菌的影响并提高氮去除率有一定理论指导意义。 Nitrification plays a key role in the biological removal of nitrogen in both nature and wastewater treatment plant (WWTP). So, understanding of the effect of organic carbon on nitrification and the competition between nitrifying bacteria and heterotrophic bacteria is important for both microbial ecology and WWTP design and operation. Despite the fact that the nitrification process of ammonia to nitrate has been extensively investigated, it is not known how the process of nitrite oxidization is affected by organic carbon when heterotrophic bacteria are present. By measuring different physiological and biochemical parameters, as well as using genomic DNA and proteome analysis, we investigated the influence of organic (acetate) on nitrite oxidizing performance, community structure and metabolic function of nitrite-oxidizing and heterotrophic bacteria under laboratory conditions. The dissertation involves two parts: Part one deals with the effect of organic matter on functional performance and bacterial community shift of nitrite-oxidizing and heterotrophic bacteria under suspended state. The bacteria were prepared in a continuous-flow stirred reactor under autotrophic condition; after two months, the nitrification rate of the culture reached about 20 mg N/ (L·d); then the bacteria were harvested for the next batch experiments. The initial concentrations of nitrite were 126 ± 6 mg N/ L in all flasks, and sodium acetate (C) to nitrite (N) ratios were 0, 0.44, 0.88, 4.41, and 8.82, respectively. The results showed that at low C/N ratios (0.44 or 0.88), the nitrite removal rate was higher than that obtained under autotrophic condition and the bacteria had single growth phase, while at high C/N ratios (4.41 or 8.82), continuous aerobic nitrification and denitrification occurred besides higher nitrite removal rates, and the bacteria had double growth phases. The community structure of total bacteria strikingly varied with the different C/N ratios; the dominant populations shifted from autotrophic and oligotrophic bacteria (NOB, and some strains of Bacteroidetes, Alphaproteobacteria, Actinobacteria, and green nonsulfur bacteria) to heterotrophic and denitrifying bacteria (strains of Gammaproteobacteria, especially Pseudomonas stutzeri and P. nitroreducens). Part two describes the influence of acetate on nitrite oxidizing performance, community structure and metabolic function of nitrite-oxidizing and heterotrophic bacteria in biofilms. Bacterial enrichments was transferred into flasks with polypropylene carriers and cultured under agitated and autotrophic condition. After two month, the biofilms grown on the carriers had a nitrification rate of about 20 mg N/ (L·h); then the biofilms were refreshed with mixotrophic medium (nitrite were 200 mg N/ L in all flasks, and C/N ratios was the same as above) every 12 h. the results show: normal nitrite oxidization reactions were performed when C/N = 0, but nitrite oxidization and partial denitrification occurred with low C/N ratios (0.44 or 0.88). At high C/N ratios (4.41 or 8.82), we mainly observed denitrification. In contrast to C/N = 0, the nitrite oxidization rate was unaffected when C/N = 0.44, but decreased with C/N = 0.88. The structure of bacterial communities varied significantly between autotrophic and mixotrophic conditions. Nitrobacter was hard to detect by PCR-DGGE while heterotrophs and especially denitrifiers were in the majority under mixotrophic conditions. Real-time PCR indicated that the Nitrobacter population decreased from 2.42 × 104 to 1.34 × 103 16S rRNA gene copies/ ng DNA, while the quantity of denitrifiers obviously increased from 0 to 2.51×104 nosZ gene copies/ ng DNA with an increasing C/N ratio. SDS-PAGE indicated the complexity of and a certain difference between the proteome of nitrite-oxidizing and heterotrophic bacteria at different C/N ratios. We conclude that the influence of organic matter on nitrite oxidation and the community structure of NOB and heterotrophic bacteria is complex. In this dissertation, we focused on how sodium acetate influenced the system both under suspended state and in biofilms. We observed that acetate did not necessarily have a negative impact on nitrification. Instead, an appropriate amount of acetate benefited both nitrite oxidization and denitrification. These findings provide a greater understanding about the relationship between organics and nitrification; they fill the gaps in the field of microbial ecology of nitrifying bacteria; they also provide insight into how to minimize the negative impact of heterotrophic bacteria and maximize the benefit of nitrogen removal in biological treatment systems.

黄、东海海洋异养细菌的生态学研究

该文利用表面荧光显微镜观测计数法和[甲基-<'-3>H]胸腺嘧啶示踪法对春秋两季节中国黄、东海异养细菌生态分布及其生产力状况,以及异养细菌及其生产力与浮游植物叶绿素、无机氮盐之间的关系进行了研究.主要内容如下：春秋两季节黄东海海洋异养细菌丰度大致相当,异养细菌平均值在5～7×10<'8>Cell/l范围之间.春季异养细菌丰度总体表现为随离岸越远先逐渐降低后略微增高的趋势,秋季异养细菌丰度有离岸越远逐渐增高的趋势.秋季黄、东海海洋异养细菌生产力明显高于春季,并且秋季异养细菌的生长率也高于春季.秋季异养细菌生产力与初级生产的比值明显高于春季,且东海高于黄海.春季异养细菌生物量与浮游植物叶绿素及无机氮盐之间无明显相关性.秋季异养细菌生物量与浮游植物叶绿素相关性在东海有较显著相关性,在黄海该相关性比东海低;异养细菌生物量与NO<,3>ˉ和DIN表现出明显相关性,该相关性在黄海明显高于东海.异养细菌在一年的变化有明显规律,冬季最低,秋季和春季相当.在一天当中,异养细菌数量变化有一定规律性,且其变化与浮游植物细胞数量变化有一定关系.

Typhoon effects on DOC dynamics in a phosphate-limited reservoir

To explore typhoon effects on dissolved organic carbon (DOC) dynamics, field investigations (tributary and dam site) and laboratory experiments (bioassay and DOC consumption) were conducted in a subtropical reservoir. A tributary survey indicated that after typhoon disruption, upstream areas were the sources of phosphate (P) but not DOC for the dam site located downstream. Bioassay experiments verified P-limitation on bacteria and phytoplankton during summer stratification, and bacteria showed a faster response than algae to added P. Experiments indicated that DOC consumption was determined by the availability of P. The 4 yr typhoon period (June-September) data of the dam site denoted that DOC concentration (27 to 270 mu M C) and its rate of change (-13 to 24 mu M C d(-1)) varied more dramatically in the weak (2006 and 2007) than in the strong (2004 and 2005) typhoon years. The negative correlation of DOC with the ratio of bacterial production (BP) to primary production (PP) in the euphotic zone (0 to 10 m) signified the interactive effects of auto- and heterotrophic processes on DOC variation. In the aphotic zone, the variation of DOC could be ascribed to the change of BP, which showed a positive correlation with P concentrations. This study documents that DOC concentration in the studied system varied at multiple time scales. Such variation can be explained by the decoupling between BP and PP, which is believed to be a function of the limiting nutrient's availability. More importantly, this study suggests that the P supply introduced by strong typhoons might have substantiated a tighter coupling between BP and PP, so that the amplitude of DOC oscillation during the summer period was effectively reduced.

Distribution pattern of marine flagellate and its controlling factors in the central and north part of the Huanghai Sea in early summer

A survey was carried out in the central and north part of the Huanghai Sea (34.5degrees similar to 37.0degreesN, 120.5degrees similar to124.0degreesE) during June 12 similar to 27, 2000. It was found that the abundance of marine flagellate ranged from 45 to 1278 cell/ml, 479 cell/ml in average. Flagellate was more abundant in the central part than in the north part of Huanghai Sea, and the abundance decreased with the increasing distance from the coast, showing a similar distribution pattern with isotherm. Vertically, high density of flagellate was always presented in the bottom of thermocline, and formed a dense accumulation in the central area of the Huanghai Sea Cold Water Mass. The effects of physical and biological factors on the distribution of marine flagellate in early summer were discussed. Water temperature (especially the existence of thermocline) rather than salinity showed significant effect on the distribution pattern of marine flagellate in the Huanghai Sea in early summer. When comparing the abundance of marine flagellate with that of other microorganisms, it revealed a comparatively stable relationship among these organhisms, with a ratio of heterotrophic bacteria: cyanobacteria: flagellate: dinoflagellate: ciliate being 10(5) 10(3):10(2):10(1):10(0).

The characteristics of nutrient removal and inhibitory effect of Ulva clathrata on Vibrio anguillarum 65

To investigate the ecological effect of macroalgae on de-eutrophication and depuration of mariculture seawater, the variation of dissolved inorganic nitrogen (DIN) and phosphate (DIP), the amount of Vibrio anguillarum, and total heterotrophic bacteria in Ulva clathrata culture, as well as on the algal surface, were investigated by artificially adding nutrients and V. anguillarum strain 65 from February to April 2006. The results indicated that U. clathrata not only had strong DIN and DIP removal capacities, but also showed a significant inhibitory effect on V. anguillarum, although not reducing the total heterotrophic bacteria. Vibrio anguillarum 65 dropped from 5 similar to 8 x 10(7) cfu mL(-1) to 10 cfu mL(-1) (clone-forming units per mL) in 10 g L-1 of fresh U. clathrata culture within 2 days; i.e., almost all of the Vibrios were efficiently eradicated from the algal culture system. Our results also showed that the inhibitory effect of U. clathrata on V. anguillarum strain 65 was both DIN- and DIP-dependent. Addition of DIN and DIP could enhance the inhibitory effects of the algae on the Vibrio, but did not reduce the total heterotrophic bacteria. Further studies showed that the culture suspension in which U. clathrata was pre-cultured for 24 h also had an inhibitory effect on V. anguillarum strain 65. Some unknown chemical substances, either released from U. clathrata or produced by the alga associated microorganisms, inhibited the proliferation of V. anguillarum 65.

Fine scale variability in methanol uptake and oxidation in the micro-layer and near-surface waters of the Atlantic

The aim of this research was to make the first depth profiles of the microbial assimilation of methanol carbon and its oxidation to carbon dioxide and use as an energy source from the microlayer to 1000 m. Some of the highest reported methanol oxidation rate constants of 0.5–0.6 d−1 were occasionally found in the microlayer and immediately underlying waters (10 cm depth), albeit these samples also showed the greatest heterogeneity compared to other depths down to 1000 m. Methanol uptake into the particulate phase was exceptionally low in microlayer samples, suggesting that any methanol utilised by microbes in this environment is for energy generation. The sea surface microlayer and 10 cm depth also showed a higher proportion of bacteria with a low DNA content, and bacterial leucine uptake rates in surface microlayer samples were either less than or the same as those in the underlying 10 cm layer. The average methanol oxidation and particulate rates were however statistically the same throughout the depths sampled, although the latter were highly variable in the near-surface 0.25–2 m compared to deeper depths. The statistically significant relationship demonstrated between uptake of methanol into particles and bacterial leucine incorporation suggests that many heterotrophic bacteria could be using methanol carbon for cellular growth. On average, methanol bacterial growth efficiency (BGEm) in the top 25 m of the water column is 6% and decreases with depth. Although, for microlayer and 10 cm-depth samples, BGEm is less than the near-surface 25–217 cm, possibly reflecting increased environmental UV stress resulting in increased maintenance costs, i.e. energy required for survival. We conclude that microbial methanol uptake rates, i.e. loss from seawater, are highly variable, particularly close to the seawater surface, which could significantly impact upon seawater concentrations and hence the air–sea flux.

Fine-scale variability in methanol uptake and oxidation: from the microlayer to 1000 m.

The aim of this research was to make the first depth profiles of the microbial assimilation of methanol carbon and its oxidation to carbon dioxide and use as an energy source from the microlayer to 1000 m. Some of the highest reported methanol oxidation rate constants of 0.5–0.6 d−1 were occasionally found in the microlayer and immediately underlying waters (10 cm depth), albeit these samples also showed the greatest heterogeneity compared to other depths down to 1000 m. Methanol uptake into the particulate phase was exceptionally low in microlayer samples, suggesting that any methanol utilised by microbes in this environment is for energy generation. The sea surface microlayer and 10 cm depth also showed a higher proportion of bacteria with a low DNA content, and bacterial leucine uptake rates in surface microlayer samples were either less than or the same as those in the underlying 10 cm layer. The average methanol oxidation and particulate rates were however statistically the same throughout the depths sampled, although the latter were highly variable in the near-surface 0.25–2 m compared to deeper depths. The statistically significant relationship demonstrated between uptake of methanol into particles and bacterial leucine incorporation suggests that many heterotrophic bacteria could be using methanol carbon for cellular growth. On average, methanol bacterial growth efficiency (BGEm) in the top 25 m of the water column is 6% and decreases with depth. Although, for microlayer and 10 cm-depth samples, BGEm is less than the near-surface 25–217 cm, possibly reflecting increased environmental UV stress resulting in increased maintenance costs, i.e. energy required for survival. We conclude that microbial methanol uptake rates, i.e. loss from seawater, are highly variable, particularly close to the seawater surface, which could significantly impact upon seawater concentrations and hence the air–sea flux.

Nanoplankton and picoplankton in the Western English Channel: abundance and seasonality from 2007–2013

The nano- and picoplankton community at Station L4 in the Western English Channel was studied between 2007 and 2013 by flow cytometry to quantify abundance and investigate seasonal cycles within these communities. Nanoplankton included both photosynthetic and heterotrophic eukaryotic single-celled organisms while the picoplankton included picoeukaryote phytoplankton, Synechococcus sp. cyanobacteria and heterotrophic bacteria. A Box–Jenkins Transfer Function climatology analysis of surface data revealed that Synechococcus sp., cryptophytes, and heterotrophic flagellates had bimodal annual cycles. Nanoeukaryotes and both high and low nucleic acid-containing bacteria (HNA and LNA, respectively) groups exhibited unimodal annual cycles. Phaeocystis sp., whilst having clearly defined abundance maxima in spring was not detectable the rest of the year. Coccolithophores exhibited a weak seasonal cycle, with abundance peaks in spring and autumn. Picoeukaryotes did not exhibit a discernable seasonal cycle at the surface. Timings of maximum group abundance varied through the year. Phaeocystis sp. and heterotrophic flagellates peaked in April/May. Nanoeukaryotes and HNA bacteria peaked in June/July and had relatively high abundance throughout the summer. Synechococcus sp., cryptophytes and LNA bacteria all peaked from mid to late September. The transfer function model techniques used represent a useful means of identifying repeating annual cycles in time series data with the added ability to detect trends and harmonic terms at different time scales from months to decades.

Role of zooplankton dynamics for Southern Ocean phytoplankton biomass and global biogeochemical cycles

Global ocean biogeochemistry models currently employed in climate change projections use highly simplified representations of pelagic food webs. These food webs do not necessarily include critical pathways by which ecosystems interact with ocean biogeochemistry and climate. Here we present a global biogeochemical model which incorporates ecosystem dynamics based on the representation of ten plankton functional types (PFTs); six types of phytoplankton, three types of zooplankton, and heterotrophic bacteria. We improved the representation of zooplankton dynamics in our model through (a) the explicit inclusion of large, slow-growing zooplankton, and (b) the introduction of trophic cascades among the three zooplankton types. We use the model to quantitatively assess the relative roles of iron vs. grazing in determining phytoplankton biomass in the Southern Ocean High Nutrient Low Chlorophyll (HNLC) region during summer. When model simulations do not represent crustacean macrozooplankton grazing, they systematically overestimate Southern Ocean chlorophyll biomass during the summer, even when there was no iron deposition from dust. When model simulations included the developments of the zooplankton component, the simulation of phytoplankton biomass improved and the high chlorophyll summer bias in the Southern Ocean HNLC region largely disappeared. Our model results suggest that the observed low phytoplankton biomass in the Southern Ocean during summer is primarily explained by the dynamics of the Southern Ocean zooplankton community rather than iron limitation. This result has implications for the representation of global biogeochemical cycles in models as zooplankton faecal pellets sink rapidly and partly control the carbon export to the intermediate and deep ocean.

A preliminary survey of micro-organisms in the gut and pellets of a tropical millipede Doratogonus uncinatus Attems (Diplopoda, Spirostreptida, Spirostreptidae).

Millipede gut microbiology and decomposition of faecal pellets over a period of eight weeks were studied in the laboratory. Bacterial numbers, carbon and nitrogen content, pH and weight loss were monitored. Heterotrophic bacteria were the most abundant and reached a peak in the first two weeks of decomposition. The amount of carbon was constant while ammonium nitrogen decreased from 1.51 % to 0.03 % after eight weeksThe pH of the pellets was slightly acidic and did not change much during the course of decomposition. A succession of micro-organisms was observed on decomposing pellets. Zygomycetes were replaced by Ascomycetes after 20 days of decomposition. Decomposition was significantly affected by temperature. The rate of decomposition was highest at 35[degree]C .

Phylogenetic and functional diversity of estuarine bacterioneuston

A micro-camada superficial da água (SML) é caracterizada pela ocorrência de grandes quantidades de compostos orgânicos, pela acumulação de contaminantes antropogênicos e é submetida a uma intensa radiação solar, extrema mudança de temperatura e, no caso dos estuários, flutuação de salinidade. Estas propriedades físico-químicas estão, provavelmente, a modular a comunidade bacteriana (bacterioneuston) com propriedades filogenéticas e funcionais específicas. Neste estudo, as abordagens dependentes e independentes do cultivo foram aplicadas para avaliar a estrutura e dinâmica das comunidades bacterioneuston e bacterioplâncton em três localizações geográficas ao longo do estuário da Ria de Aveiro. Além disso, comparámos a diversidade filogenética de grupos específicos (Aeromonas, Pseudomonas e Psychrobacter) presentes em bacterioneuston e bacterioplâncton. Finalmente, as duas comunidades foram comparadas em termos de prevalência e diversidade de bactérias resistentes aos antibióticos e respetivos genes de resistência. Bactérias heterotróficas cultiváveis foram enriquecidas em SML. Eletroforese em gel de gradiente desnaturante (DGGE) permitiu a identificação de filotipos específicos em SML. Além disso, a análise de agrupamento dos perfis de DGGE de ambas as comunidades revelou uma ligeira tendência de agrupamento de acordo com a camada amostrada. As diferenças entre as duas comunidades variaram de acordo com factores espaciais e temporais. Em termos de diversidade filogenética de grupos específicos, não foram identificadas diferenças consistentes entre SML e UW com relação às comunidades de Aeromonas. Com relação ao género Pseudomonas, uma unidade operacional taxonómica cultivável foi consistentemente hiper-representada nas amostras de SML. Metodologias dependentes e independentes do cultivo revelaram a presença de populações de Psychrobacter complexas e muito estáveis em todos os sítios e datas de amostragens, com diferenças significativas entre as comunidades de Psychrobacter presentes em SML e UW. Estirpes representativas de prováveis novas espécies também foram cultivadas. Em termos de resistência aos antibióticos, a prevalência de bactérias resistentes em SML foi alta sugerindo selecção pelas condições presentes em SML. É preciso enfatizar que a resistência aos antibióticos foi incomum entre as bactérias estuarinas e os mecanismos de resistência foram, predominantemente, intrínsecos. Pela combinação de abordagens inovadoras dependentes e independentes do cultivo, este estudo forneceu novas e consistentes informações com relação às diferenças em ambas as comunidades bacterianas e em relação a alguns dos fatores que contribuem para a sua formação.

Ecophysiology of nontuberculous Mycobacteria in marine aquaculture ponds

The world demand for fish and fishery products is increasing steadily and it is generally accepted that it will not be possible to meet the heavy demand with resources exploited from capture fishery alone. Now aquaculture is well established and fastdeveloping industry in many countries and is a major focus sector for development. During recent decades, aquaculture has gained momentum, throughout the world especially in developing countries. According to Food and Agricultural Oganisation (FAO, 2000), global aquaculture production was 26.38 tones in 1996 have reached 32.9 million tonnes during 1999. Only marine aquaculture sector has contributed 13.1 million tonnes during 1999.India is a major fish producing country. About one half of lndia’s brackish water lands are currently being utilized for farming in order to reduce the gap between supply and demand for fish. Aquaculture has become a major source of livelihood for people and its role in integrated rural development, generation of employment and earning foreign exchange, thereby alleviating poverty is being greatly appreciated around the world.Among the infectious agents, bacteria are becoming the prime causal organisms for diseases in food fishes and other marine animals. Sindermann, (1970) reported that bacterial fish pathogen most commonly found among marine fishes is species of Pseudomonas, Vibrio and Mycobacterium. These can be categorized into primary pathogens; secondary invaders that may cause systemic disease in immunocompromised hosts; and normal marine flora which are not pathogenic but may occur on body surfaces or even within the tissues of the host. I-Iigh density of animals in hatchery tanks and ponds is conducive to the spread of pathogen and the aquatic environment with regular application of protein rich feed, is ideal for culturing bacteria. Bacteria, which are normally present in seawater or on the surface of fish, can invade and cause pathological effects in fishes, which are injured or subjected to other environmental stresses.Mycobacteria except parasites are known as nontuberculosis mycobacteria (NTM), atypical mycobacteria or mycobacteria other than tuberculosis(MO'l'l"). This group of mycobacteria includes opportunistic pathogens and saprophytes. Environmental mycobacteria are ubiquitous in distribution and the sources may include soil, water, warm-blooded as well as cold-blooded animals. Disease caused by environmental mycobacterial strains in susceptible humans (Goslee & Wolinsky, 1976; Grange, 1987), animals and fishes are increasingly attracting attention. Greatest importance of environmental mycobacteria is believed to be their role in immunological priming of humans and animals, thereby modifying their immune responses to subsequent exposure to pathogenic species.

Diversity and effectiveness of tropical mangrove soil microflora on the degradation of polythene carry bags

The diversity and load of heterotrophic bacteria and fungi associated with the mangrove soil from Suva, Fiji Islands, was determined by using the plate count method. The ability of the bacterial isolates to produce various hydrolytic enzymes such as amylase, gelatinase and lipase were determined using the plate assay. The heterotrophic bacterial load was considerably higher than the fungal load. There was a predominance of the gram positive genus, Bacillus. Other genera encountered included Staphylococcus, Micrococcus, Listeria and Vibrio. Their effectiveness on the degradation of commercial polythene carry bags made of high density polyethylene (HDPE) and low density polyethylene (LDPE) was studied over a period of eight weeks in the laboratory. Biodegradation was measured in terms of mean weight loss, which was nearly 5 % after a period of eight weeks. There was a significant increase in the bacterial load of the soil attached to class 2 (HDPE) polythene. After eight weeks of submergence in mangrove soil, soil attached to class 1 and class 3 polythene mostly had Bacillus (Staphylococcus predominated in class 2 polythene). While most of the isolates were capable of producing hydrolytic enzymes such as amylase and gelatinase, lipolytic activity was low. Class 2 HDPE suffered the greatest biodegradation.

Biogeochemistry of the shelf sediments of south eastern Arabian sea: Effect on benthic bacterial heterotrophs

The composition and variability of heterotrophic bacteria along the shelf sediments of south west coast of India and its relationship with the sediment biogeochemistry was investigated. The bacterial abundance ranged from 1.12 x 103 – 1.88 x 106 CFU g-1 dry wt. of sediment. The population showed significant positive correlation with silt (r = 0.529, p< 0.05), organic carbon (OC) (r = 0.679, p< 0.05), total nitrogen (TN) (r = 0.638, p< 0.05), total protein (TPRT) (r = 0.615, p< 0.05) and total carbohydrate (TCHO) (r = 0.675, p< 0.05) and significant negative correlation with sand (r = -0.488, p< 0.05). Community was mainly composed of Bacillus, Alteromonas, Vibrio, Coryneforms, Micrococcus, Planococcus, Staphylococcus, Moraxella, Alcaligenes, Enterobacteriaceae, Pseudomonas, Acinetobacter, Flavobacterium and Aeromonas. BIOENV analysis explained the best possible environmental parameters i.e., carbohydrate, total nitrogen, temperature, pH and sand at 50m depth and organic matter, BPC, protein, lipid and temperature at 200m depth controlling the distribution pattern of heterotrophic bacterial population in shelf sediments. The Principal Component Analysis (PCA) of the environmental variables showed that the first and second principal component accounted for 65% and 30.6% of the data variance respectively. Canonical Correspondence Analysis (CCA) revealed a strong correspondence between bacterial distribution and environmental variables in the study area. Moreover, non-metric MDS (Multidimensional Scaling) analysis demarcated the northern and southern latitudes of the study area based on the bioavailable organic matter