isolation-native-soil-microorganisms-with-potential-for-breaking-down

Isolation of Native Soil Microorganisms with Potential for Breaking Down Biodegradable Plastic Mulch Films Used in Agriculture

Fungi native to agricultural soils that colonized commercially available biodegradable mulch (BDM) films were isolated and assessed for potential to ...

Texas Tech University

The impact and frequency of forest harvesting could significantly affect soil microbial community (SMC) structure and functioning. The ability of soil microorganisms to perform biogeochemical processes is critical for sustaining forest productivity and has a direct impact on decomposition dynamics and carbon storage potential. The Wind River Canopy Crane Research Forest in SW, WA, provided a unique opportunity to study a forest chronosequence and the residual effects of harvesting on the SMC in comparison to old-growth forests. The objective of this study was to determine the effect of clear-cutting and stand age on temporal dynamics of SMC and physiological stress markers using phospholipid fatty acid (PLFA) profiling. Soil microbial PLFA profiles were determined seven times over 22 months (Nov. 02 to Sep. 04) in old-growth coniferous forest stands (300-500 years) and 8 (CC8)- or 25 (CC25)-year-old replanted clear-cuts. PLFA patterns of the SMC shifted because of clear-cutting, but seasonal temporal changes had greater shifts than differences among stand age. The microbial biomass (total PLFA) and bacterial, fungal, and selected other PLFAs were significantly reduced in CC8 but not in CC25 sites relative to the old-growth sites. An increase in stress indicators [PLFA ratios of saturated/monsaturated and (cy17:0 + cy19:0)/(16:1omega7 + 18:1omega7)] in late summer was related to water stress. Although the canopy and litter input are quite different for a 25-year clear-cut compared to virgin old-growth forest, we conclude that the composition of the microbial communities, 25 years after clear-cutting, has recovered sufficiently to be much more similar to old-growth forests than a recent clear-cut at this Pacific Northwest forest site. The study shows the potential of PLFA analysis for profiling microbial communities and their stress status under field conditions, but wide temporal shifts emphasize the need for sampling over seasons to fully interpret ecosystem management impacts on microbial populations.

PLFA profiling of microbial community structure and seasonal shifts in soils of a Douglas-fir chronosequence.

L&#39;incidence et la fr&eacute;quence de l&#39;exploitation foresti&egrave;re pourraient affecter significativement la structure de la communaut&eacute; microbienne (SMC) du sol et fonctionnement. La capacit&eacute; des microorganismes du sol pour effectuer les processus biog&eacute;ochimiques est critique pour le maintien de la productivit&eacute; foresti&egrave;re et a un impact direct sur la dynamique de la d&eacute;composition et le potentiel de stockage de carbone. La for&ecirc;t de recherche Wind River Canopy Crane dans SW, WA, a fourni une occasion unique d&#39;&eacute;tudier une chronos&eacute;quence for&ecirc;t et les effets r&eacute;siduels de l&#39;exploitation sur du SMC en comparaison avec vieilles for&ecirc;ts. L&#39;objectif de cette &eacute;tude &eacute;tait de d&eacute;terminer l&#39;effet de la coupe &agrave; blanc et l&#39;&acirc;ge sur la dynamique temporelle de la SMC et marqueurs de stress physiologique &agrave; l&#39;aide de phospholipides acides gras (AGPL) profilage du peuplement. Profils d&#39;AGPL microbiennes du sol ont &eacute;t&eacute; d&eacute;termin&eacute;es &agrave; sept fois plus de 22 mois (du 02 novembre au 04 sept.) dans les peuplements de vieilles for&ecirc;ts de conif&egrave;res (300 &agrave; 500 ans) et 8 (CC8) ou 25 (CC25) - ann&eacute;e-vieux replant&eacute; des coupes &agrave; blanc. Mod&egrave;les AGPL du SMC d&eacute;cal&eacute; en raison de la coupe &agrave; blanc, mais les variations temporelles saisonni&egrave;res avaient des quarts de travail plus grande que les diff&eacute;rences entre l&#39;&acirc;ge du peuplement. La biomasse microbienne (total AGPL) et bact&eacute;riennes, fongiques et certains autres AGPL ont chut&eacute; dans CC8 mais pas dans les sites CC25 par rapport &agrave; des sites d&#39;anciennes. Une augmentation des indicateurs de stress [rapports AGPL satur&eacute;/monsaturated et (cy17:0 + cy19:0) / (16:1omega7 + 18:1omega7)] &agrave; la fin de l&#39;&eacute;t&eacute; &eacute;tait li&eacute; au stress hydrique. Bien que la canop&eacute;e et la liti&egrave;re d&#39;entr&eacute;e sont tout &agrave; fait diff&eacute;rentes pour une coupe &agrave; blanc de 25 ans par rapport &agrave; la for&ecirc;t vierge, nous concluons que la composition des communaut&eacute;s microbiennes, 25 ans apr&egrave;s la coupe &agrave; blanc, a r&eacute;cup&eacute;r&eacute; suffisamment pour &ecirc;tre beaucoup plus semblable aux for&ecirc;ts anciennes qu&#39;une coupe &agrave; blanc r&eacute;cente &agrave; ce site de for&ecirc;t du Nord-Ouest du Pacifique. L&#39;&eacute;tude montre le potentiel d&#39;analyse AGPL pour le profilage des communaut&eacute;s microbiennes et leur &eacute;tat de contrainte dans des conditions r&eacute;elles, mais les d&eacute;calages temporels large soulignent la n&eacute;cessit&eacute; d&#39;&eacute;chantillonnage sur les saisons pour interpr&eacute;ter compl&egrave;tement ecosystem management impacts sur les populations microbiennes.

AGPL profilage de la structure des communaut&eacute;s microbiennes et saisonniers se d&eacute;place dans les sols d&#39;une chronos&eacute;quence de sapin de Douglas.

L&#39;impatto e la frequenza di raccolta foresta potrebbe incidere in modo significativo del suolo comunit&agrave; microbica (SMC) struttura e funzionamento. La capacit&agrave; di eseguire processi biogeochimici microorganismi del terreno &egrave; fondamentale per sostenere la produttivit&agrave; di foresta e ha un impatto diretto sulla scomposizione dinamica e potenziale di immagazzinamento di carbonio. Wind River Canopy Crane ricerca foresta in SW, WA, fornito un&#39;opportunit&agrave; unica per studiare una foresta chronosequence e gli effetti residui del raccolto su SMC rispetto alle foreste di vecchio-sviluppo. L&#39;obiettivo di questo studio era di determinare l&#39;effetto di dissodamento e stand et&agrave; su dinamiche temporali di SMC e marcatori di stress fisiologico con profilatura di fosfolipidi di acidi grassi (PLFA). Profili PLFA microbiche del terreno sono state determinate sette volte oltre 22 mesi (Nov. 02 Sep 04) nei basamenti di vecchio-sviluppo foresta conifera (300-500 anni) e 8 (CC8) o 25 (CC25) - anno-vecchio ripiantati clear-cuts. Modelli di PLFA di SMC spostato a causa di dissodamento, ma stagionale cambiamenti temporali avevano turni maggiore rispetto le differenze tra l&#39;et&agrave; di stand. La biomassa microbica (totale PLFA) e batteriche, fungine e selezionati altri PLFAs sono stati ridotti significativamente in CC8 ma non in siti CC25 rispetto al vecchio-sviluppo siti. Un aumento in indicatori di stress [rapporti PLFA saturi/monsaturated e (cy17:0 + cy19:0) / (16:1omega7 + 18:1omega7)] alla fine dell&#39;estate era legato a stress idrico. Sebbene il baldacchino e la cucciolata di ingresso sono abbastanza differenti per un 25 anni pulito rispetto alla foresta vergine, possiamo concludere che la composizione delle comunit&agrave; microbiche, 25 anni dopo il dissodamento, ha recuperato sufficientemente per essere molto pi&ugrave; simili a foreste di vecchio-sviluppo di un recente diffuso presso questo sito della foresta nord-ovest Pacifico. Lo studio dimostra le potenzialit&agrave; di analisi PLFA per l&#39;analisi di comunit&agrave; microbiche e del loro stato di stress in condizioni di campo, ma temporali ampi spostamenti sottolineano la necessit&agrave; di campionamento nelle stagioni di interpretare pienamente ecosistema gestione degli impatti sulle popolazioni microbiche.

Jennifer Moore-Kucera

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