Enhancing methane production from lignocellulosic biomass by combined steam‑explosion pretreatment and bioaugmentation with cellulolytic bacterium Caldicellulosiruptor bescii

Background: Biogas production from lignocellulosic biomass is generally considered to be challenging due to the recalcitrant nature of this biomass. In this study, the recalcitrance of birch was reduced by applying steam-explosion (SE) pretreatment (210 °C and 10 min). Moreover, bioaugmentation with the cellulolytic bacterium Caldicellulosiruptor bescii was applied to possibly enhance the methane production from steam-exploded birch in an anaerobic digestion (AD) process under thermophilic conditions (62 °C). Results: Overall, the combined SE and bioaugmentation enhanced the methane yield up to 140% compared to untreated birch, while SE alone contributed to the major share of methane enhancement by 118%. The best methane improvement of 140% on day 50 was observed in bottles fed with pretreated birch and bioaugmentation with lower dosages of C. bescii (2 and 5% of inoculum volume). The maximum methane production rate also increased from 4-mL CH4/ g VS (volatile solids)/day for untreated birch to 9-14-mL CH4/ g VS/day for steam-exploded birch with applied bioaugmentation. Bioaugmentation was particularly effective for increasing the initial methane production rate of the pretreated birch yielding 21-44% more methane than the pretreated birch without applied bioaugmentation. The extent of solubilization of the organic matter was increased by more than twofold when combined SE pretreatment and bioaugmentation was used in comparison with the methane production from untreated birch. The beneficial effects of SE and bioaugmentation on methane yield indicated that biomass recalcitrance and hydrolysis step are the limiting factors for efficient AD of lignocellulosic biomass. Microbial community analysis by 16S rRNA amplicon sequencing showed that the microbial community composition was altered by the pretreatment and bioaugmentation processes. Notably, the enhanced methane production by pretreatment and bioaugmentation was well correlated with the increase in abundance of key bacterial and archaeal communities, particularly the hydrolytic bacterium Caldicoprobacter, several members of syntrophic acetate oxidizing bacteria and the hydrogenotrophic Methanothermobacter. Conclusion: Our findings demonstrate the potential of combined SE and bioaugmentation for enhancing methane production from lignocellulosic biomass

Anatomical characteristics and hydrologic signals in tree-rings of oaks (Quercus robur L.)

Q. robur decline in European floodplain forests in recent years seems to be strongly associated with the deteriorating hydrological regime. We investigated the influence of the Krka River flow on tree-ring patterns of Q. robur from the Krakovo floodplain forests (Slovenia) to assess the effect of micro-location conditions on hydrological signals in wood-anatomical characteristics. We selected two groups of Q. robur trees growing at nearby locations with different hydrological conditions, resulting in frequent autumn and spring flooding at the wetter site (=W oaks) but no flooding at the other, drier site (=D oaks). We found differences between the two groups in the anatomical structure of tree-rings; however, ring width proved to be the main variable determining the anatomical structure of oak wood. D and W oaks responded differently to the Krka River flow in the studied period. Radial growth of D oaks was negatively influenced by spring flow, but positively influenced by minimum summer flow. In W oaks, ring width was positively correlated with mean summer flow. Thus, environmental information stored in wood-anatomical features may vary, even within the same forest stand, and largely depends on the micro-environment. Reduced wood increments of D oaks suggest that growth conditions are less favourable, implying a link between the health state of oaks from lowland forest and hydrological conditions. Trees intended for hydrological reconstruction must therefore be carefully selected to avoid the possibility of error and potential loss of information. Anatomical characteristics and hydrological signals in tree-rings of oaks from areas with regular flooding may vary, even within the same forest stand, and largely depends on the micro-environmental conditions

COMMITMENT IN MARKETING RESEARCH SERVICES: TWO ALTERNATIVE MODELS / ĮSIPAREIGOJIMAI ATLIEKANT RINKODAROS TYRIMUS: DU ALTERNATYVŪS MODELIAI

The paper aims to contribute to the body of knowledge on client commitment in business-to-business professional services by developing and testing two alternative models: one based on the Relationship Marketing (RM) approach and the second on the Industrial Marketing and Purchasing Group (IMP) approach. Both models include the same mediators (components of commitment) and consequences (attitudinal and behavioral loyalty), yet they differ in the antecedents of commitment. By using SEM, both models are tested and compared on a sample of 150 firms. The results show that affective commitment is the only component of commitment that influences both attitudinal and behavioral loyalty. In the RM model affective commitment is positively influenced by trust, social bonds and satisfaction, while in the IMP model it is positively influenced by trust and knowledge transfers. Although differences in the sizes of effects can be found, the two models perform comparably well in terms of the model fit and their explanatory power of loyalty. Santrauka Straipsnio tikslas - nustatyti žinių lygį, kurį yra pasiekę profesionalai, organizuojantys paslaugų teikimą pagal modelį verslas verslui. Autoriai pasirinko du modelius: vienas pagrįstas rinkodaros ryšių (MR), kitas - gamybinės rinkodaros ir prekybos grupių (IMP) požiūriu. Abu modeliai apima tokius parametrus, kaip įsipareigojimai, ir tokius rezultatus, kaip vartotojų lojalumas, požiūris, tačiau skirtingas pradines sąlygas. Atliekant tyrimus modeliai buvo pritaikyti 150 įmonių. Kaip teigia straipsnio autoriai, gauti tyrimo rezultatai rodo, kad emocinis įsipareigojimas yra sudėtinė įsipareigojimų, turinčių įtakos lojalumui bei vartotojų požiūrio formavimui, dalis. Pritaikius pasirinktus modelius gaunami atitinkami rezultatai. Reikšminiai žodžiai: įsipareigojimas, rinkodara, rinkodaros tyrimai,  verslas verslu