Industrial Recycling Networks as Starting Points for Broader Sustainability‐Oriented Cooperation?

Closing loops by intercompany recycling of by‐products is a core theme of industrial ecology (IE). This article considers whether industrial recycling networks or industrial symbiosis projects can be used as a starting point for much broader intercompany cooperation for sustainable development. Evidence presented is based on the results of an empirical investigation of the recycling network Styria in Austria, the recycling network Oldenburger Münsterland in Germany, and the manufacturing sector in Austria. Statistical analysis shows that the percentage of by‐products that are passed on to other companies for recycling purposes is not higher in member companies of the recycling networks than in the other companies of the manufacturing sector in Austria. In terms of cooperation, the relationships with the respective recycling partners are found to be very similar to regular customer relations. Furthermore, the companies of the recycling networks remain unaware of the network to which they belong. Instead, one of the main findings of this study is that intercompany recycling activities are regarded by the company representatives as bilateral market transactions, not as collaborative network activities. This has potentially significant implications for the use of industrial symbiosis networks as starting points for sustainability networks with broader cooperation toward sustainability. The findings raise interesting questions as to whether such broader cooperation might result from a conscious planning process or might emerge largely spontaneously as part of normal market coordination. In any case, intercompany recycling is clearly considered to be a very important field of collaborative action for sustainability in industry.     

Symbiotic streptomycetes in antennal glands of the South American digger wasp genus Trachypus (Hymenoptera,Crabronidae)

Several insect taxa have evolved symbioses with actinobacteria that protect the host or its nutritional resources against pathogens. Digger wasps of the genus Philanthus (‘beewolves’; Hymenoptera, Crabronidae) cultivate ‘Candidatus Streptomyces philanthi’ (Ca. S. philanthi) in specialized antennal glands and transfer them to subterranean brood cells, where the symbionts provide protection for the beewolf larva against pathogens by producing a cocktail of antibiotic substances. The present study investigates the occurrence of antennal symbionts in two species of the genus Trachypus, which is the closest relative to Philanthus. Cross sections of the antennae from females of both Trachypus denticollis and Trachypus boharti reveal bacteria‐containing gland reservoirs that are morphologically very similar to those found in Philanthus spp. Polymerase chain reaction‐based screens with specific primers, sequencing of the partial 16S rRNA gene, and fluorescence in situ hybridization confirm the presence of close relatives of ‘Ca. S. philanthi’ in T. denticollis and T. boharti. However, 16S rRNA sequence divergence between Trachypus spp. and Philanthus spp. symbionts is much higher for T. boharti than for T. denticollis, suggesting that horizontal transmission and/or de novo uptake of symbionts from the environment occurs occasionally. The results obtained indicate that the protective symbiosis with antennal actinobacteria is older and more widespread than previously recognized and occurs in at least two genera of digger wasps that comprise approximately 170 species.     

Growth of an invasive legume is symbiont limited in newly occupied habitats

Mutualisms may play an important role in the establishment and invasion success of introduced species, but their influence is little studied. To test whether a lack of root nodule symbionts may limit the performance of invasive legumes, seedlings of Cytisus scoparius were introduced to an old-field habitat and then either inoculated with Bradyrhizobium strains from existing C. scoparius populations, or left uninoculated. In two separate years, inoculation more than doubled average plant biomass. For uninoculated transplants, nodule formation was positively correlated with proximity to plants of the native legume Desmodium canadense , but not related to distance from a second legume species, Apios americana. Polymerase chain reaction assays and DNA sequencing confirmed that bacteria isolated from uninoculated C. scoparius plants were indistinguishable from Bradyrhizobium strains in root nodules of D. canadense . By contrast, bacterial strains associated with A. americana were never found in C. scoparius nodules. Transplants in seven other habitats across a 160 km region also showed a highly significant, fivefold biomass increase in response to inoculation. Thus, colonizing legumes can suffer from a scarcity of nodule symbionts. However, certain indigenous legumes may create favourable microhabitats for invasion, by increasing symbiont availability in their vicinity.     

Communication of cyanobacteria with plant partners during association formation

Data are presented on the physiological diagnostics of cyanobacterial communication with higher plants in natural symbioses (plant syncyanoses) and in model associations, as well as on the interaction of the partners without spatial integration. Emphasis is placed on changes in cyanobacterial features important for symbiogenesis. The multicomponent composition and the possible nature of the factors that enable partner communications are discussed with hormogonia formation and taxis as an example.     

Sex-specific differences and the role of predation in the interaction between the hermit crab, Pagurus longicarpus, and its epibiont, Hydractinia symbiolongicarpus

The interaction between the hermit crab, Pagurus longicarpus, and the shell epibiont, Hydractinia symbiolongicarpus, varies from mutualism to parasitism based on the environmental context. We tested the hypothesis that this interaction also varies as a function of hermit crab sex. Given that recent work showed a negative effect of Hydractinia on female reproduction, we predicted a greater frequency of males in Hydractinia shells in the field and a stronger preference by males than females for shells with Hydractinia. Field collections documented a significantly greater proportion of males than females occupying shells with Hydractinia, and a significantly greater proportion of ovigerous females than non-ovigerous females in shells with Hydractinia. In laboratory shell-switching experiments, a greater proportion of males than females chose to enter shells with Hydractinia, but there was no difference in the proportions of males and females that vacated shells with Hydractinia.We examined whether the presence of Hydractinia influenced predation rates. Blue crabs fed on more than twice as many hermit crabs in shells with Hydractinia as compared to bare shells, but there was no significant difference for stone crabs. Laboratory experiments showed that the force required to crush shells was significantly greater for shells without Hydractinia. Thus, the lower occupancy and preference exhibited by females than males for shells with Hydractinia appears to result both from the decreased reproduction shown in past studies and an increase in predation risk.     

Bacterial epibionts and endolichenic actinobacteria and fungi in the Lower Devonian lichen Chlorolichenomycites salopensis

The charcoalified fragment of the dorsiventrally organized, internally stratified presumed green algal lichen Chlorolichenomycites salopensis from the Lower Devonian Lochkovian strata in the Welsh Borderland carries bacterial colonies on the upper surface, i.e. the cortex, and actinobacterial filaments in the medulla underneath the photobiont layer. Moreover relatively thin hyphae of presumed endolichenic fungi were found. As in extant lichens, which are best regarded as consortia with an unknown number of participants, this internally stratified, fossil thallus fragment of a presumed green algal lichen harbours a diverse microbial community.     

Control of NO level in rhizobium-legume root nodules: Not only a plant globin story

Nitric oxide (NO) is a gaseous signaling molecule which plays both regulatory and defense roles in animals and plants. In the symbiosis between legumes and rhizobia, NO has been shown to be involved in bacterial infection and nodule development steps as well as in mature nodule functioning. We recently showed that an increase in NO level inside Medicago truncatula root nodules also could trigger premature nodule senescence. Here we discuss the importance of the bacterial Sinorhizobium meliloti flavohemoglobin to finely tune the NO level inside nodules and further, we demonstrate that S. meliloti possesses at least two non redundant ways to control NO and that both systems are necessary to maintain efficient nitrogen fixing activity.     

The involvement of Medicago truncatula non-specific lipid transfer protein N5 in the control of rhizobial infection

Cysteine-rich proteins seem to play important regulatory roles in Medicago truncatula/Sinorhizobium meliloti symbiosis. In particular, a large family of nodule-specific cysteine-rich (NCR) peptides is crucial for the differentiation of nitrogen-fixing bacteroids. The Medicago truncatula N5 protein (MtN5) is currently the only reported non-specific lipid transfer protein necessary for successful rhizobial symbiosis; in addition, MtN5 shares several characteristics with NCR peptides: a small size, a conserved cysteine-rich motif, an N-terminal signal peptide for secretion and antimicrobial activity. Unlike NCR peptides, MtN5 expression is not restricted to the root nodules and is induced during the early phases of symbiosis in root hairs and nodule primordia. Recently, MtN5 was determined to be involved in the regulation of root tissue invasion; while, it was dispensable for nodule primordia formation. Here, we discuss the hypothesis that MtN5 participates in linking the progression of bacterial invasion with restricting the competence of root hairs for infection.