Involvement of methyltransferases enzymes during the energy metabolism of the anaerobic archaeon methanosarcina semesiae sp. Nov.

The methyl group transfer from dimethylsulfide (DMS), trimethylamine and methanol to 2-mercaptoethanesulfonic acid (coenzyme M) were investigated from cell extracts of Methanosarcina semesiae sp. nov. to evaluate whether the enzyme systems involved were constitutive or inductive. The extracts from cells grown on DMS exhibited methanogenic activity exclusively with DMS and methanethiol. Likewise when cells were pre-grown on trimethylamine or methanol the extracts only produced methane from the respective metaboilic substrate. Dimethylsulfide:methyl-coenzyme M transferase activity was dependent on ATP, but hydrogen did not stimulate activity. The fact that ATP could be replaced by the reductant Ti(III)-citrate indicates that reductive activation of methyl transfer reaction in DMS conversion proceeds in a manner similar to methyltransferasesinvolved in methanol and trimethylamine conversion, but with a different reduction source. This source appears to be limited since sometimes the cell extracts were totally inactive in the presence of ATP, while still being activated with Ti(III)-citrate. It was concluded that enzymes involved inmethyl transfer reactions are specific for each substrate; DMS, trimethylamine and methanol and have to be induced. Further investigations are recommended to corroborate the current study

Assessment of fecal bacteria contamination in sewage and non-sewage impacted mangrove ecosystems along the coast of Dar es salaam

Microbiological quality of the intertidal pool water was evaluated in sewage impacted (Mtoni Kijichi) and non-sewage impacted (Rasi Dege) mangrove forest sites along the coast of Dar es Salaam, Tanzania. The Most Probable Number method was used for estimating the total coliform (TC), fecal coliform (FC) and fecal enterococci (ENT) levels. In addition, physicochemical parameters (temperature, pH, salinity and nutrients) were measured. The results for microbial fecal indicators were compared to the World Health Organisation (WHO) and United States Environmental Protection Agency (USEPA) guidelines for marine recreational and shellfish harvesting waters. Fecal bacteria contamination was significantly higher at Mtoni Kijichi than at Rasi Dege mangroves Nutrient levels were also significantly higher at Mtoni Kijichi than Rasi Dege). No significant variation was noted on the values of temperature, pH and salinity. A significant correlation between the levels of fecal bacteria indicators and nutrient concentrations was observed at both sites. Regarding compliance to WHO and USEPA guidelines, only one station at Mtoni Kijichi was found to have levels exceeding the recommended thresholds for marine recreational waters. The high level of fecal bacteria contamination and nutrients was attributed to anthropogenic activities. Further studies and education of the users of these ecosystems is recommended

abundance and diversity of seagrass and macrofauna in the intertidal areas with and without seaweed farming activities in the east coast of Zanzibar

The diversity and abundance of seagrass and associated macrofauna were studied in transects with and without seaweed farms at Chwaka Bay and Jambiani, in the East Coast of Zanzibar. Eight seagrass species, namely Cymodocea rotundata, Cymodocea serrulata, Thalassia hemprichii,Thalassodendron ciliatum, Syringodium isoetifolium, Halodule uninervis, Halophila ovalis and Enhalus acoroides were recorded in the transects. The mean total biomass of seagrass at Chwaka Bay ranged from 142.4 ± 70.71 to 1652 ± 772.7 g dw/m2 and 212.9 ± 146.2 to 1829 ± 1692 gdw/m2 in station with and without seaweed farms, respectively. At Jambiani, the mean total biomass ranged from 880.4 ± 336.8 to 3467 ± 549.9 and 203.4 ± 102.4 to 3810 ± 2770 g dw/m2 in station with and without seaweed farms, respectively. The overall total biomass of seagrasswas significantly lower (KW = 108.7, p < 0.0001) in station with seaweed farms than in stations without seaweed farms. A total of 93 macrofauna species representing 60 families were encountered and the mean density ranged from 910 to 6990 individuals/m2 at Chwaka Bay andJambiani in stations with and without seaweed farms respectively. The most common macrofauna species were Codakia punctata, Meropesta nicobarica, Echinometra mathaei, Pinna muricata and Clibanarius emystemus. It was shown that the macrofauna abundance and diversity was higher in stations without seaweed farms than in the stations with seaweed farms, which could be due to activities associated with seaweed farming which contributed to the loss of diversity and biomass of flora and macrofauna of the seagrass meadows

Performance of Subsurface Flow Constructed Wetland for Domestic Wastewater Treatment

Constructed wetlands (CW) have recently emerged as efficient technology for secondary treatment of wastewater in developing countries because of its low cost, ease operation, maintenance and generally good performance. At present there are a number of small scale units of CW for wastewater treatment in Tanzania but information on their performance is scarce. This study investigated the removal efficiency of fecal bacteria indicators, inorganic nutrients and Biochemical Oxygen Demand (BOD) from wastewater by a CW at the University of Dar es Salaam. The CW received wastewater from a primary facultative pond and was a monoculture system planted with Phragmites mauritianus (&gt; 10 years old) with one unplanted cells as control. The results showed significantly (P &lt; 0.001) higher removal of fecal indicator bacteria, in planted than in unplanted cells. Thus, the overall E. Coli and Fecal coliform percentage removal were 92.9±6.05% and 93.2±6.13% in planted cells as compared to unplanted cell which were 75.2±21.3% and 58.7±21.2%, respectively. The BOD5 values in influent was also significantly (P &lt; 0.001) reduced (71 ± 6.2%) in effluent of planted cells than in unplanted cells where the average percentage removal averaged 45 ± 3.3%. Similarly, nutrients were significantly (P &lt; 0.001) removed in planted cells compared to unplanted cells. The results of this study show that plants enhanced the removal process and that the CW are efficient in wastewater treatment, supporting the ideas put forward by several researchers on the usefulness of these systems in developing countries. The system continues to perform efficiently for long time which signifies its cost effectiveness. It is recommended that CW be promoted for sewage treatment in a strategy to reduce wastewater pollution in Tanzania

The interaction between a sexually transferred steroid hormone and a female protein regulates oogenesis in the malaria mosquito anopheles gambiae

Molecular interactions between male and female factors during mating profoundly affect the reproductive behavior and physiology of female insects. In natural populations of the malaria mosquito Anopheles gambiae, blood-fed females direct nutritional resources towards oogenesis only when inseminated. Here we show that the mating-dependent pathway of egg development in these mosquitoes is regulated by the interaction between the steroid hormone 20-hydroxy-ecdysone (20E) transferred by males during copulation and a female Mating-Induced Stimulator of Oogenesis (MISO) protein. RNAi silencing of MISO abolishes the increase in oogenesis caused by mating in blood-fed females, causes a delay in oocyte development, and impairs the function of male-transferred 20E. Co-immunoprecipitation experiments show that MISO and 20E interact in the female reproductive tract. Moreover MISO expression after mating is induced by 20E via the Ecdysone Receptor, demonstrating a close cooperation between the two factors. Male-transferred 20E therefore acts as a mating signal that females translate into an increased investment in egg development via a MISO-dependent pathway. The identification of this male–female reproductive interaction offers novel opportunities for the control of mosquito populations that transmit malaria

Eliminating Malaria Vectors.

Malaria vectors which predominantly feed indoors upon humans have been locally eliminated from several settings with insecticide treated nets (ITNs), indoor residual spraying or larval source management. Recent dramatic declines of An. gambiae in east Africa with imperfect ITN coverage suggest mosquito populations can rapidly collapse when forced below realistically achievable, non-zero thresholds of density and supporting resource availability. Here we explain why insecticide-based mosquito elimination strategies are feasible, desirable and can be extended to a wider variety of species by expanding the vector control arsenal to cover a broader spectrum of the resources they need to survive. The greatest advantage of eliminating mosquitoes, rather than merely controlling them, is that this precludes local selection for behavioural or physiological resistance traits. The greatest challenges are therefore to achieve high biological coverage of targeted resources rapidly enough to prevent local emergence of resistance and to then continually exclude, monitor for and respond to re-invasion from external populations

Methanethiol-dependent dimethylsulfide production in soil environments

Dimethylsulfide (DMS) is an environmentally important trace gas with roles in sulfur cycling, signalling to higher organisms and in atmospheric chemistry. DMS is believed to be predominantly produced in marine environments via microbial degradation of the osmolyte dimethylsulfoniopropionate (DMSP). However, significant amounts of DMS are also generated from terrestrial environments, for example, peat bogs can emit ~6 μmol DMS m−2 per day, likely via the methylation of methanethiol (MeSH). A methyltransferase enzyme termed ‘MddA’, which catalyses the methylation of MeSH, generating DMS, in a wide range of bacteria and some cyanobacteria, may mediate this process, as the mddA gene is abundant in terrestrial metagenomes. This is the first study investigating the functionality of MeSH-dependent DMS production (Mdd) in a wide range of aerobic environments. All soils and marine sediment samples tested produced DMS when incubated with MeSH. Cultivation-dependent and cultivation-independent methods were used to assess microbial community changes in response to MeSH addition in a grassland soil where 35.9% of the bacteria were predicted to contain mddA. Bacteria of the genus Methylotenera were enriched in the presence of MeSH. Furthermore, many novel Mdd+ bacterial strains were isolated. Despite the abundance of mddA in the grassland soil, the Mdd pathway may not be a significant source of DMS in this environment as MeSH addition was required to detect DMS at only very low conversion rates

The Microbiome of Brazilian Mangrove Sediments as Revealed by Metagenomics

Here we embark in a deep metagenomic survey that revealed the taxonomic and potential metabolic pathways aspects of mangrove sediment microbiology. The extraction of DNA from sediment samples and the direct application of pyrosequencing resulted in approximately 215 Mb of data from four distinct mangrove areas (BrMgv01 to 04) in Brazil. The taxonomic approaches applied revealed the dominance of Deltaproteobacteria and Gammaproteobacteria in the samples. Paired statistical analysis showed higher proportions of specific taxonomic groups in each dataset. The metabolic reconstruction indicated the possible occurrence of processes modulated by the prevailing conditions found in mangrove sediments. In terms of carbon cycling, the sequences indicated the prevalence of genes involved in the metabolism of methane, formaldehyde, and carbon dioxide. With respect to the nitrogen cycle, evidence for sequences associated with dissimilatory reduction of nitrate, nitrogen immobilization, and denitrification was detected. Sequences related to the production of adenylsulfate, sulfite, and H2S were relevant to the sulphur cycle. These data indicate that the microbial core involved in methane, nitrogen, and sulphur metabolism consists mainly of Burkholderiaceae, Planctomycetaceae, Rhodobacteraceae, and Desulfobacteraceae. Comparison of our data to datasets from soil and sea samples resulted in the allotment of the mangrove sediments between those samples. The results of this study add valuable data about the composition of microbial communities in mangroves and also shed light on possible transformations promoted by microbial organisms in mangrove sediments

Community Awareness on Microbial Water Pollution and Its Effects on Health Development in Urban Tanzania: A Case Study of Tabata and Kiwalani Wards in Ilala District in Dar es Salaam Region

This article is based on a study that investigated community awareness on the problem of water pollution and established its relationship to socio-economic development in urban Tanzania, with a focus on a case study of Ilala Municipality in Dar es Salaam region. A sample of 160 respondents (men and women) from Tabata and Kiwalani wards in Ilala district were randomly selected and interviewed. Data was collected through questionnaire, focus group discussions, participant observation, and documentary reviews. Findings revealed that water pollution has been a major problem confronting most of Dar es Salaam residents. Ignorance on effects of microbial water pollution has resulted in tremendous ill health, which, in turn, has had negative consequences on socio-economic development. Indeed, frequent endemic water-borne diseases in the studied area were found to be a result of lack of awareness on water pollution. The majority of respondents 156 (97.5%) rely on dug wells that are very close to pit latrines, and drink water without boiling. In addition, 54 respondents (33.8%) had little knowledge on what causes water pollution. Although some respondents were aware of the possibility of acquiring diseases from untreated water, they continue using water from wells and boreholes due to the lack of safe tap water and poverty (ability to boil water). In addition, many of the respondents did not know the status of their water, although there are many scientific reports indicating that most of the well water in this area is faecal-polluted. As such, knowledge on water pollution is lacking. The study recommends government intervention by supplying safe-water and educating people in order to avoid occurrence of gastro-intestinal diseases. In addition, there is a need to give feedback of scientific results obtained from scientific research to the society