Consequences of detritus type in an aquatic microsystem: effects on water quality, micro-organisms and performance of the dominant consumer

1. Variation in detritus quality and quantity can have significant effects on aquatic invertebrate food webs. Allochthonous inputs of detritus are the principal energy source for organisms in aquatic tree hole microsystems. We compared the effects of two major detritus types found in tree holes, senescent leaves (Sugar Maple and White Oak) and invertebrate carcasses (dead adult fruit flies and crickets), on several water quality characteristics of laboratory microcosms as well as on mass, survival and population performance of the dominant tree hole consumer, Ochlerotatus triseriatus (Diptera: Culicidae). To date, no study has documented the effects of animal detritus in tree hole microsystems or on resident consumers.2. Aquatic environments receiving invertebrate carcasses had significantly greater total nitrogen, total reactive phosphorus and higher pH, than leaf-based environments. Decay rate of invertebrate carcasses was greater compared to leaf material. Consumption of O(2) by micro-organisms increased with increasing detritus amounts, but we detected no difference between detritus types.3. Ochlerotatus triseriatus larvae grew faster in animal-based treatments, and mean mass of larvae was significantly greater when more animal detritus was used. The effect of animal-based treatments on larvae translated into higher performance for adults, which were three times heavier than counterparts from plant-based containers. Survivorship and estimated population growth rates were significantly greater for O. triseriatus reared on animal-based versus plant-based detritus.4. We hypothesise two mechanisms for the pronounced effect of invertebrate carcasses on mosquito performance relative to that associated with leaf detritus: (i) invertebrate carcasses decompose more quickly and release nutrients more effectively into the aquatic environment; or (ii) O. triseriatus larvae may directly ingest nutrient-rich components of invertebrate carcasses. Because even relatively small animal detritus additions can have strong effects on O. triseriatus populations, studies need to be conducted to explore the overall role of animal detritus in tree holes in nature.     

滴水湖沉积物中可培养优势微生物种群初探

于滴水湖湖心采集底泥样品,对底泥中可培养优势菌种进行分离、纯化,并利用Biolog微生物自动分析系统进行鉴定。结果显示,滴水湖沉积物中菌落总数为2.43×104CFU/g,分离纯化后的8株优势菌种中,革兰氏阴性菌占87.5%,其中7株为GN-NENT(革兰氏阴性非肠道菌)、1株为GP-ROD SB(革兰氏阳性芽孢杆菌)。鉴定结果显示,8株菌种分别为:鳗鱼气单孢菌(Aeromonas encheleia)、乙酸钙不动杆菌/基因型1(Acinetobacter calcoaceticus/genospecies1)、舒氏气单胞菌(Aeromonas schubertiiDNA group12)、腐败希瓦氏菌B(Shewanella putrefaciens B)、维罗纳/温和气单胞菌(Aeromonas veronii/sobria DNA group8)、坎氏弧菌(Vibrio campbelli)、蕈状芽孢杆菌(Bacillus mycoides)和梅氏弧菌(Vibrio metschnikovii)。     

Novel cytochromes P450 applications arising from the directed-evolution of recombinant micro-organisms

AIMS: Directed (forced) evolution of cytochromes P450 (overall 2700 CYP isoforms in non-recombinant biota) is a method that has been investigated in yeasts (and other micro-organisms) by aerobically growing brewers' yeast Saccharomyces cerevisiae in very high glucose (20%) media. METHODS AND RESULTS: Mitochondrial repression subverts cytochrome oxidase biosynthesis into manifest cytochromes P450 accumulation in brewers' yeast. A similar phenomenon is observed with the acridine-induced petit mutant. Cytochromes P450 EC 1.14.14.1 (and mimics) display a range of redox iron-mediated bioconversions in food processing, with mixed function oxidase (O2:mono-oxygenase) intervention results. Unfortunately these enzymes generate reactive oxygen species (ROS) through redox electron recycling, whilst isoform CYP 1A1 can activate precarcinogens such as benzo(a)pyrene to the ultimate (proximate) carcinogen that binds to nuclear DNA. CONCLUSIONS: In conclusion, another 5000 CYP isoforms, for example, might be identified in micro-organisms and many more made to order through recombinant DNA technology and utilized both in vitro and in vivo for aimed bioconversions in industry and in the environment, as part of the impact of greener-approach supporting strategies to minimize global pollution.     

Natural products potential of Dictyoceratida sponges-associated micro-organisms

The marine environment represents one of the most underexplored environments in the world. Marine sponges have a higher taxonomic diversity according to definite environmental conditions. They have been considered interesting sources for bioactive compounds. Dictyoceratida sponges are divided into five families which are widely distributed and habituating different types of micro-organisms. However, some secondary metabolites are probably not produced by the sponges themselves, but rather by their associated micro-organisms. These secondary metabolites are characterized by different chemical structures and consequently different biological activities. This review outlines the reported secondary metabolites from micro-organisms associated with Dictyoceratida sponges and their investigated biological activities from 1991 to 2019. The increasing research studies in this field can play a major role in marine microbial natural products drug discovery in the future.     

The proteinase inhibitors of plants and micro-organisms

Recent (post-1972) advances in our knowledge of the proteinase inhibitors of plants and micro-organisms are reviewed. Details of the specificity, occurrence and distribution of these proteins are summarized, and modern methods for their isolation, purification and assay are discussed. Certain homologies revealed by comparison of the amino acid sequences of several inhibitors are noted. Details of their reactive (inhibitory) sites are tabulated and discussed in relation to the proposed mechanisms of action of these proteins. Recent experiments on the intracellular localization of the inhibitors, their physiology and possible functional roles are described. The nutritional significance, possible therapeutic use and value of the proteinase inhibitors as laboratory tools are also discussed.     

Microbial diversity in soil: effect of releasing genetically engineered micro-organisms

This review examines the potential for change in microbial diversity, with the emphasis on bacteria, in soil resulting from the introduction of genetically engineered microorganisms (GEMs). With the advent of GEMs came the impetus for new technologies to recover these micro-organisms from soil and to assess their effects on microbial diversity. This review also presents general aspects of and genetic approaches to accessing bacterial diversity in the environment.